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September 1984

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Document:	VMS 4.0 VAX VMS Patch Utility Reference Manual
Order Number:	AA-Z426A-TE
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Pages:	114
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VAX/VMS
Patch Utility Reference
Manual
Order Number: AA-Z426A-TE

September 1984

This document describes the VAX/VMS Patch Utility and explains how to
examine and modify executable images and shareable images.

Revision/Update Information:

This is a new manual.

Software Version:

VAX/VMS Version 4.0

digital equipment corporation
maynard, massachusetts

September 1984
The information in this document is subject to change without notice and should
not be construed as a commitment by Digital Equipment Corporation. Digital
Equipment Corporation assumes no responsibility for any errors that may appear
in this document.
The software described in this document is furnished under a license and may be
used or copied only in accordance with the terms of such license.
No responsibility is assumed for the use or reliability of software on equipment
that is not supplied by Digital Equipment Corporation or its affiliated companies.
Copyright ©1984 by Digital Equipment Corporation
All Rights Reserved.
Printed in U.S.A.
The postpaid READER'S COMMENTS form on the last page of this document
requests the user's critical evaluation to assist in preparing future documentation.
The following are trademarks of Digital Equipment Corporation:
DEC
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UNIBUS
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□BEADED
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This document was prepared using an in-house documentation production system. All
page composition and make-up was performed by T^X, the typesetting system developed
by Donald E. Knuth at Stanford University. T^X is a registered trademark of the American
Mathematical Society.

PATCH Contents
PREFACE

vii

NEW AND CHANGED FEATURES

FORMAT

PATCH-1

COMMAND SUMMARY

PATCH-2

DESCRIPTION

PATCH-4

USING THE PATCH UTILITY

PATCH-4

1.1

Input Image File

PATCH-5

1.2

Command Procedure

PATCH-6

1.2.1

Using the CREATE Command to Create Command
Procedures
PATCH-6

1.2.2

Using Text Editors to Create Command
Procedures

PATCH-7

Creating User-Defined Symbols in Command
Procedures

PATCH-7

1.2.3

1.3

Output Image File

PATCH-8

1.4

Journal File

PATCH-9

APPLYING PATCHES

PATCH-9

USING SYMBOLS

PATCH-10

3.1

Symbols Recognized By PATCH

PATCH-10

3.1.1

Global Symbols

PATCH-11

3.1.2

Local Symbols

PATCH-11

3.1.3

Module Names, Program Section Names, and
Routine Names

PATCH-11

3.1.4

Universal Symbols

PATCH-11

3.1.5

Symbolic Instruction Labels

PATCH-12

3.1.6

Side Effect of Using Symbolic Instruction
Labels

PATCH-13
iii

PATCH Contents

3.1.7

Symbols Defined with the DEFINE
Command

3.2

The PATCH Symbol Table

PATCH-15

3.3

Translating Symbols And Values

PATCH-16

3.3.1

Translating Symbols into Address Values

PATCH-16

3.3.2

Translating Address Values into Symbols

PATCH-17

3.4

Commands That Affect Symbols and Pathnames

PATCH-17

USING ENTRY AND DISPLAY MODES

PATCH-18

4.1

Context Modes

PATCH-18

4.1.1

INSTRUCTION-NOINSTRUCTION Modes

PATCH-19

4.1.2

ASCII-NOASCII Modes

PATCH-19

4.1.3

SYMBOLS-NOSYMBOLS Modes

PATCH-19

4.2

Length Modes

PATCH-20

4.3

Radix Modes

PATCH-20

4.4

Symbol Search Modes

PATCH-20

USING PATCH AREA

PATCH-21

5.1

Patch Area Descriptor

PATCH-21

5.2

Patch Area Symbols

PATCH-21

5.3

Default Patch Area

PATCH-22

5.4

User-defined Patch Area

PATCH-22

5.4.1
5.4.2
*

5.5

PATCH-15

Creating and Accessing a User-Defined Patch
Area

PATCH-23

Terminating the Use of a User-Defined Patch
Area

PATCH-23

Commands That Affect Patch Area

PATCH-23

5.5.1

DEPOSIT/PATCH AREA Command

PATCH-24

5.5.2

INSERT/INSTRUCTION Command

PATCH-24

5.5.3

REPLACE/INSTRUCTION Command

PATCH-24

RULES OF SYNTAX

PATCH-25

6.1

Entering ASCII Data Strings

PATCH-25

6.2

Entering VAX MACRO Instructions

PATCH-25

PATCH Contents

Entering Numeric Data

PATCH-27

Delimiting Parameter Values

PATCH-28

Special Operators For Arithmetic Expressions

PATCH-28

Special Operators For Addressing Locations

PATCH-29

COMMAND QUALIFIERS

PATCH-30

/ABSOLUTE

PATCH-31

/JOURNAL

PATCH-33

/NEW—VERSION

PATCH-34

/OUTPUT

PATCH-36

/UPDATE

PATCH-37

/VOLUME

PATCH-40

COMMANDS

PATCH-41

ALIGN

PATCH-42

CANCEL MODE

PATCH-44

CANCEL MODULE

PATCH-45

CANCEL PATCH-AREA

PATCH-47

CANCEL SCOPE

PATCH-48

CHECK ECO

PATCH-49

CHECK NOT ECO

PATCH-51

CREATE

PATCH-52

DEFINE

PATCH-54

DELETE

PATCH-56

DEPOSIT

PATCH-59

EVALUATE

PATCH-62

EXAMINE

PATCH-65

EXIT

PATCH-68

HELP

PATCH-69
V

PATCH Contents

INSERT

PATCH-70

REPLACE

PATCH-73

SET ECO

PATCH-77

SET MODE

PATCH-78

SET MODULE

PATCH-80

SET PATCH-AREA

PATCH-81

SET SCOPE

PATCH-85

SHOW MODE

PATCH-86

SHOW MODULE

PATCH-87

SHOW PATCH-AREA

PATCH-88

SHOW SCOPE

PATCH-89

UPDATE

PATCH-90

VERIFY

PATCH-91

INDEX
EXAMPLES

PATCH-94

Preface

Intended Audience
This manual is intended to be used by experienced system programmers who
are writing or modifying executable images and shareable images. Familiarity
with a patching utility is not required; this manual provides introductory
information on PATCH and on PATCH concepts and terminology.

Structure of This Document
This document is composed of five major sections.
The Format Section is an overview of PATCH and is intended as a quick
reference guide. The format summary contains the DCL command that
invokes PATCH, listing all command qualifiers and parameters. The usage
summary describes how to invoke and exit from PATCH, how to direct
output, and any restrictions you should be aware of. The command summary
lists all commands that can be used within PATCH.
The Description Section explains how to use PATCH.
The Qualifier Section describes each DCL command qualifier. Qualifiers
appear in alphabetical order.
The Command Section describes each PATCH command. Commands appear
in alphabetical order.
The Examples Section contains examples of common operations that you
perform with PATCH.

Associated Documents
Four other manuals that may be of use:

•
•
•
•

Guide to Using DCL and Command Procedures on VAX/VMS
VAX/VMS DCL Dictionary
Guide to VAX/VMS System Management and Daily Operations
Guide to Writing a Device Driver for VAX/VMS

vii

Preface

Conventions Used in This Document
Convention

Meaning

Iret]

A symbol with a one- to three-character
abbreviation indicates that you press a key on
the terminal, for example, |ret| .

|CTRL/x|

The phrase CTRL/x indicates that you must press
the key labeled CTRL while you simultaneously
press another key, for example, CTRL/C, CTRL/Y,
CTRL/0.

PATCH> EXAMINE/ASCII
650
00000650: 'FE 7

Command examples show all output lines or
prompting characters that the system prints
or displays in black letters. All user-entered
commands are shown in red letters.
Vertical series of periods, or ellipsis, mean either
that not all the data that the system would display
in response to the particular command is shown or
that not all the data a user would enter is shown.
Vertical ellipsis in coding examples indicate that
lines of code not pertinent to the example are
omitted.

file-spec,...

Horizontal ellipsis indicates that additional
parameters, values, or information can be entered.

/JOURNAL[=file-spec]

Square brackets indicate that the enclosed item
is optional. (Square brackets are not, however,
optional in the syntax of a directory name in a
file specification or in the syntax of a substring
specification in an assignment statement.)

quotation marks
apostrophes

The term quotation marks is used to refer to
double quotation marks ("). The term apostrophe
(7) is used to refer to a single quotation mark.

New and Changed Features
This manual documents the Patch Utility in Version 4.0 of VAX/VMS. This
section summarizes the main technical changes from Version 3.0:
•

The /ABSOLUTE command qualifier has been included in the list of
PATCH DCL command qualifiers. This qualifier allows the user to patch a
file at absolute virtual addresses.

•

The /NEW—VERSION command qualifier has been included in the list of
PATCH DCL command qualifiers. This qualifier controls whether a new
version of the patched file is created or the contents of the existing file are
modified in place.

•

Several new examples have been added to the manual including examples
for the /ABSOLUTE and /NEW_VERSION qualifiers, and two, moredetailed examples in the Examples Section.

PATCH

PATCH
The VAX/VMS Patch Utility (PATCH) allows you make changes
to an image file in the form of patches. You can then run the new
version of the image without having to compile, assemble, or link
the program source files.

FORMAT

PATCH file-spec
Command Qualifiers
/ABSOLUTE
/JOURNA L[=file-spec]
/NEW— VERSION
/OUTPUT[=file-spec]
/UPDA TE[=(eco-level [, ...])]
/VOLUME[=n]

Defaults
None.
None.
/NEW— VERSION
None.
None.
None.

Command Parameter
file-spec
Specifies the name of the image file to be patched or a command procedure
that contains both the name of the image file to be patched and PATCH
commands.
If the file specification denotes an image file, the file specification must
include the file name. If you omit the remaining fields (device, directory, file
type, and version number), PATCH uses your default device and directory,
assumes a file type of EXE, and uses the highest version of the specified file.
If the file specification denotes a command procedure, the file-spec parameter
must be preceded by an at sign (@). Only the file name is required. If you
omit the remaining fields (device, directory, file type, and version number),
PATCH uses your default device and directory, assumes a file type of COM,
and locates the highest version of the command procedure.
No wildcard characters are allowed in the file specification.

usage summary

Invoking
To invoke PATCH, use the PATCH command.

Exiting
To end a PATCH session, enter the EXIT command or press CTRL/Z.

Directing Output
To direct output, use the /OUTPUT qualifier with the PATCH command.

Privileges/Restrictions
None.

PATCH-1

PATCH

commands

Syntax

PATCH> command [parameter]
PATCH Commands

ALIGN
/BYTE
/WORD
/LONG
/QUAD
/PAGE
CANCEL MODE
CANCEL MODULE
/ALL
CANCEL PATCH_AREA
CANCEL SCOPE
CHECK ECO
CHECK NOT ECO
CREATE
DEFINE
DELETE
/BYTE
/WORD
/LONG
/OCTAL
/DECIMAL
/HEXADECIMAL
/[NOJASCII
/[NOJINSTRUCTION
/[NO]SYMBOLS
/[NOJGLOBALS
/[NOJSCOPE
DEPOSIT
/BYTE
/WORD
/LONG
/OCTAL
/DECIMAL
/HEXADECIMAL
/[NO] ASCI I
/[NOJINSTRUCTION
/[NO]SYMBOLS
/[NOJGLOBALS
/[NO]SCOPE
/PATCH_AREA
EVALUATE
/BYTE
/WORD
/LONG
/OCTAL
/DECIMAL
/HEXADECIMAL
/[NO] ASCI I
/[NO]INSTRUCTION
/[NOJSYMBOLS
/[NOJGLOBALS
/[NO]SCOPE
PATCH-2

PATCH

EXAMINE
/BYTE
/WORD
/LONG
/OCTAL
/DECIMAL
/HEXADECIMAL
/[NOJASCII
/[NO]INSTRUCTION
/[NO]SYMBOLS
/[NOJGLOBALS
/[NOJSCOPE
EXIT
HELP
INSERT
/OCTAL
/DECIMAL
/HEXADECIMAL
/[NO]INSTRUCTION
/[NO]SYMBOLS
/[NO]GLOBALS
/[NOJSCOPE
REPLACE
/BYTE
/WORD
/LONG
/OCTAL
/DECIMAL
/HEXADECIMAL
/[NOJASCII
/[NOJINSTRUCTION
/[NOJSYMBOLS
/[NOJGLOBALS
/[NOJSCOPE
SET ECO
SET MODE
SET MODULE
/ALL
SET PATCH_ARE A
/INITIALIZE=size-expression
SET SCOPE
SHOW MODE
SHOW MODULE
SHOW PATCH—ARE A
SHOW SCOPE
UPDATE
VERIFY
/BYTE
/WORD
/LONG
/OCTAL
/DECIMAL
/HEXADECIMAL
/[NOJASCII
/[NOJINSTRUCTION
/[NOJSYMBOLS
/[NOJGLOBALS
/[NOJSCOPE
PATCH-3

PATCH
Description

DESCRIPTION

After you have compiled or assembled and linked a program, you may need
to make changes to the code. The VAX/VMS Patch Utility (PATCH) provides
an extensive set of commands that allows you to make changes to an image
file in the form of patches. You can then execute the patched program
without recompiling or reassembling and relinking.
PATCH also provides several features to help you find and correct erroneous
code. These features include:
•

Use of symbols to reference locations

•

Patch area to store additional data and instructions

•

Entry and display modes to control the environment in which PATCH
accepts your commands and displays its output

PATCH may be used to maintain executable image files, shareable image
files, and device-driver image files written by users in any language supported
by the VAX/VMS operating system.
In many cases, you will want to use the VAX/VMS Symbolic Debugger
before using PATCH. The debugger lets you make temporary changes to your
code; you can then use PATCH to make permanent any debugger sessions.
(Of course, the source code will not reflect these changes until you change the
source by using a text editor.) See the Symbolic Debugger in the VAX/VMS
Utilities Reference Volume for more information.

Using the Patch Utility
PATCH requires two types of input: the image file to be modified, and the
PATCH commands to be executed. You can use PATCH by entering com¬
mands during an interactive terminal session. When the PATCH commands
are executed, the requested changes are made.
You can also submit a command procedure for PATCH to execute during in¬
teractive or batch mode processing. During patching by means of a command
procedure, you enter the name of a PATCH command procedure that con¬
tains the name of the image file to be patched and the PATCH commands to
be applied. A PATCH command procedure can be created during a PATCH
session, or with a text editor. See Section 1.2 for detailed information on
using a command procedure with PATCH.
The Patch Utility provides a number of commands that allow you to modify
the input image file. Some of the commands include the following:
•

The ECO commands to initiate, identify, and monitor the patches you
apply to an image file. The SET ECO command assigns a unique ECO
level to a patch. The CHECK ECO and CHECK NOT ECO commands test
whether specified ECO levels have or have not been set.

•

The CREATE command to create a PATCH command procedure.

•

The UPDATE command to apply a patch to an image file.

All the PATCH commands are explained in detail in the Commands Section.

PATCH—4

PATCH
Description

In addition to the PATCH commands, you can use other PATCH features
when modifying the input image file. PATCH is a symbolic utility. You can
pass symbol information to PATCH or define new symbols during a PATCH
session, then use that symbolic information as a reference tool. See Section 3
for information on using symbols.
When referencing locations in the image file, you can use the entry and
display modes that PATCH provides. See Section 4 for more information on
entry and display modes.
PATCH provides a storage space called patch area when you need to add
additional instructions or data entries. See Section 5 for information on using
patch area.
When you patch an image file, PATCH can produce the following three
output files:
File

Description

Output image file

An updated image file. This file must be explicitly
created using the UPDATE command.

Journal file

An ASCII file containing a record of the PATCH
session. This file is automatically created by PATCH
and provides an easy way to keep track of the
changes and attempted changes made to an image
file.

Command procedure

A file containing all successful PATCH commands
that can subsequently be used as input to PATCH.
This file must be explicitly created using the CREATE
command.

The output image file and command procedure are optional files. You must
request them for PATCH to create them. PATCH automatically creates a
journal file.

1.1

Input Image File
The input image file is the file you want to update. Because PATCH is not
a language-dependent utility, you can use it to update an image file written
in any language supported by the VAX/VMS operating system. The only
restriction is that the input image file must be created by the VAX/VMS
Linker.
Note: PATCH is not intended for customer use on DIGITAL software. Any
revisions applied to this software, except those contained in DIGITALsupplied automatic update kits, may make it difficult for you to install fu¬
ture software updates. Furthermore, application of patches to VAX/VMS
software that are not supplied by DIGITAL invalidates the warranty on
the DIGITAL-supplied VAX/VMS software.
The input image file can be a shareable image, device driver image, or
executable image.
An executable image is the most common type of image. An executable
image is one that can be run by a process. Patching an executable image
requires no special rules or considerations.

PATCH-5

PATCH
Description

A shareable image is an image that does not have a starting address and must
be linked with one or more object modules to produce an executable image.
You must consider the following restrictions when patching shareable images:
•

You can specify only universal symbols when patching a shareable image

•

You can use the default patch area to patch position-independent share¬
able images. When default patch area is created while patching positionindependent shareable images, PATCH propagates the image section
characteristics to the patch area image section descriptor.

•

You must, however, use a user-defined patch area to patch positiondependent images.

A device driver image is a set of routines and tables used by the operating
system to process an I/O request for a particular device type. To patch a
device driver image, you should use a user-defined patch area rather than the
default patch area to store additional instructions and data.
PATCH never alters the input image file. When you invoke PATCH, it
creates a copy of the input image fie and then incorporates your changes
into the copy. You can thus test the new image file and, if it does not run
correctly, still have the original file to reevaluate.
You can also patch files (including nonimage files) by specifying the
/ABSOLUTE qualifier with the PATCH command. See the description of
this qualifier in the Command Qualifiers section for information on how to do
this.

1.2

Command Procedure
You can use a command procedure to apply patches to an image file. A
command procedure is a sequence of commands (and, optionally, input data)
that performs a task in a manner similar to a program.
Used with PATCH, a command procedure is a file of PATCH commands that,
when the command procedure is executed, will apply patches to a particular
image file. Usually, you create a command procedure to ease the task of
patching multiple copies of an image file. Instead of manually patching each
file, you can submit a command procedure for interactive or batch mode
processing.
There are two ways to create command procedures. One way is to use the
PATCH command CREATE. The second way is to use an interactive text
editor. Both ways are described below.

1.2.1

Using the CREATE Command to Create Command Procedures
After you invoke PATCH, issue the CREATE command to request that a
command procedure be created and opened. PATCH automatically inserts
the name of the input image file as the first entry in the command procedure.
Subsequent commands that affect the image are then written into this file.
Commands that are used only to display information are not written to the
file; these include EXAMINE, HELP, EVALUATE, SHOW MODE, SHOW
MODULE, SHOW PATCH__AREA, and SHOW SCOPE.
As PATCH writes commands into the command procedure, all symbolic
references are changed to absolute values. This translation occurs because
symbol information is not always passed to the image file during compiling or
assembling and linking. For example, if an image file has been linked without

PATCH—6

PATCH
Description

the /DEBUG qualifier, neither local nor global symbol information appears in
the image's symbol table. Hence, when using the PATCH command CREATE
to create a command procedure, PATCH changes all symbolic references to
absolute values to ensure that the command procedure will execute properly.
PATCH also automatically abbreviates all commands, in command procedures
created using CREATE, to conserve space.
Section 1.2.3 shows an example of creating a command procedure with the
CREATE command.

1.2.2

Using Text Editors to Create Command Procedures
You can use a text editor, such as EDT, to construct command procedures.
When you do so, the first entry in the command procedure must be the name
of the input image file that is to incorporate the patches. Then enter PATCH
command lines to the file in the order that you want PATCH to process them.
When you use a text editor to create command procedures, you can use
symbolic references as long as PATCH is able to resolve these references
when the command procedure is run. If PATCH is unable to resolve a
symbolic reference, the command procedure will be prematurely terminated.
If you want to use local symbols that have been previously defined in the
image file, you must issue the SET MODULE command at the beginning
of the command procedure to enter these symbols into the PATCH symbol
table.
The following example shows how to create a command procedure that can
be used to modify the image file TEST.EXE;2. TEST.EXE;2 contains the local
symbol LOOP. The command procedure TEST.COM contains the following
lines:
TEST. EXE; 2
SET MODULE/ALL
SET ECO 3
REPLACE/INSTRUCTION L00P='ADDL2 #2,R3'

UPDATE
EXIT

The first PATCH command, SET MODULE/ALL, places the local symbols
from all modules in TEST.EXE;2 into the PATCH symbol table. After this,
you can use the symbol LOOP to indicate the address of the instruction
ADDL2 #2,R3.

1.2.3

Creating User-Defined Symbols in Command Procedures
PATCH command procedures can contain many patches if each patch starts
with a unique ECO level and ends with the UPDATE command. If the
patches within a command procedure contain user-defined symbols, you
should initialize these symbols at the start of the command procedure.
User-defined symbols are symbols defined with the DEFINE command.
The following describes why user-defined symbols should be initialized and
shows how to initialize them.
A patch's ECO level is one factor that determines whether or not the patch is
applied when the command procedure is executed. If a patch in the command
procedure has an ECO level that is already set in the image file to be patched,
that particular patch is not applied.

PATCH-7

PATCH
Description

When the command procedure is executed, PATCH parses every command
line regardless of whether the command belongs to a patch that is applied.
During the parsing operation, PATCH examines each command line and
attempts to resolve all symbolic references. If a patch belongs to an ECO
level that has already been set in the image file, the commands in the patch
are parsed but not applied.
If a DEFINE command occurs in a patch that is not applied, the symbol
assignment attempted by that command is not made. Any further references
to that symbol will generate an undefined symbol message, causing the
command procedure to terminate.
PATCH can, however, resolve further references to the symbol if the symbol
was previously initialized. To initialize user-defined symbols, place them at
the beginning of the command procedure and assign the value zero (0) to
them. In the patch where the symbol is used, redefine the symbol to the
value you want to use.
The following example shows how to initialize user-defined symbols when
creating a command procedure with the CREATE command:
PATCH>CREATE PATCOM
PATCH>DEFINE FIRST=0
PATCH>DEFINE SEC0ND=0
PATCH>SET ECO 1
PATCH>DEFINE FIRST=600
PATCH>DEPOSIT/INSTRUCTION FIRST='MOVL R3, R4'
PATCH>UPDATE
PATCH>SET ECO 2
PATCH>DEFINE SEC0ND=700
PATCH>DEPOSIT/INSTRUCTION SECOND='MOVL R3. R6'
PATCH>UPDATE
PATCH>EXIT

The command procedure PATCOM.COM can now be used to patch
additional copies of the image file. Because the user-defined symbols are
initialized, PATCOM.COM will execute even if ECO level 1 or 2 is already
set in the image file to be patched.
For example, if PATCOM.COM is used to patch an image file in which ECO
1 is set, the first patch (identified by the command SET ECO 1) is not applied.
However, PATCH still tries to resolve the symbol FIRST when parsing the
DEPOSIT command line. Because FIRST was previously initialized at the
start of the procedure, PATCH is able to resolve the symbolic reference.
If FIRST had not been initialized, an error would have occurred, and the
command procedure would have been terminated.

1.3

Output Image File
The output image file is a copy of the image file that has been updated. It
consists of all the changes performed by the commands, and the original data
that was not altered. An output image file is always created after you enter
the UPDATE command. If you fail to enter the UPDATE command, PATCH
does not create an output image file.
During a single execution of PATCH, you can apply several patches to an
image file. As you terminate each patch (by issuing the UPDATE command),
PATCH updates the output image file. The first UPDATE command creates
the output image file; subsequent UPDATE commands (issued during the
current PATCH session) overwrite this file.

PATCH-8

PATCH
Description

By default, the output image file specification consists of the same file name
and type as the input image file name and type, and a version number one
greater than the highest version of the input image file. Also by default, the
file is created in your process's current default device and directory.
To change the default file specification for the output image file, use the
/OUTPUT command qualifier with the PATCH command. This qualifier is
described in the Command Qualifier Section.

Journal File
The journal file provides a complete record of all PATCH commands issued
during the editing of an input image file. A journal file entry is created every
time a PATCH command is processed. Comments written during a PATCH
session will also be recorded in the journal file. The journal file provides a
record not only of changes actually made, but also of unsuccessful attempts
to edit the input image file.
A journal file is maintained for every PATCH session. If a journal file
already exists for a particular file, the new journal entries are appended to
it. Otherwise, PATCH creates a journal file with the same file name as the
input image file name, a file type of JNL, and a version number of 1. Also
by default, the file is created in your process's current default device and
directory.
To change the default file specification for the journal file, use the /JOURNAL
command qualifier with the PATCH command. This qualifier is described in
the Command Qualifier Section.
Entries in a journal file are written as ASCII text, thereby allowing you to
examine the contents of the journal file simply by issuing the DCL command
PRINT or TYPE.

Applying Patches
Applying a patch to an image file involves the following steps:
1

Invoke PATCH.

2 Set the Engineering Change Order (ECO) level.
3 Issue PATCH commands to change the image file.
4 Apply the patch with the UPDATE command.
5 Exit from PATCH.
You can invoke PATCH to edit an image file from an interactive terminal
session or by using a command procedure (see Section 1.2).
Whichever way you invoke PATCH, use the following sequence of PATCH
commands for applying patches.
First, establish the ECO level of the patch by using the SET ECO command.
Although the use of this command is not mandatory, DIGITAL recommends
including it with your patch to make it easier for you and future users
to identify the patches made to an image file. More importantly though,
using the SET ECO command enables you to process selected patches using
command procedures.

PATCH-9

PATCH
Description

Use whichever PATCH commands you need to examine and patch the image
file. Then use the UPDATE command to apply the patch to the image file at
the specified ECO level. A patch is defined as the commands bounded by the
SET ECO and UPDATE commands.
You can then either apply another patch to the image or terminate the patch
session with the EXIT command.
The following example shows a patch applied to the image file named
NEGATION.EXE; 1:
PATCH> SET ECO 1
PATCH>EXAMINE/INSTRUCTION 606
00000606:
TSTL R4
PATCH>REPLACE/INSTRUCTION 606 = 'TSTL R4'
NEW> ' TSTL R5'
NEW>EXIT
old:
00000606:
TSTL R4
new:
00000606:
TSTL R5
PATCH>UPDATE
%PATCH-I-WRTFIL, updating image file DB1:[GARTH]NEGATION.EXE;2

In the above example, the ECO level is defined as 1. The EXAMINE com¬
mand requests that location 606 be displayed as a VAX MACRO instruction.
The REPLACE command then changes the instruction in location 606 to a
different instruction. The UPDATE command sets ECO level 1 and applies
the patch to NEGATION.EXE.

Using Symbols
When you use PATCH, you must identify the locations that contain the
erroneous instructions or data before you can change the code. That is,
you must identify the virtual addresses of the errors within the image file.
You can do so by by means of a symbolic name defined in the image file
when it was created. To ensure that symbol is available for your use, you
must include certain information at compile or assembly and link time. For
example, to pass local symbols in a MACRO program, include the /DEBUG
qualifier when you assemble and link the program.
See the appropriate language user's guide to determine which qualifiers are
required to pass symbol information to PATCH and refer to the VAX/VMS
Linker in the VAX/VMS Utilities Reference Volume to determine how to pass
universal symbols to PATCH.

Symbols Recognized By PATCH
PATCH recognizes six types of symbols:
•

Global symbols

•

Local symbols

•

Module names, program section names, and routine names

•

Universal symbols

•

Symbolic instruction labels

•

Symbols defined with the DEFINE command

PATCH also recognizes patch area symbols. See Section 5 for more informa¬
tion.

PATCH-10

PATCH
Description

PATCH cannot access local labels in VAX MACRO programs. Local labels are
symbols that consist of a number (0 through 65,535) followed by the dollar
sign.

3.1.1

Global Symbols
Global symbols are symbols defined in one module to be accessed by any
number of other modules.
You indicate a global symbol in your source program by delimiting it with
a special operator. This operator depends on the language in which your
program is written. For example, in VAX MACRO, you define a global
symbol by using double colons (::) or double equal signs (==). (Individual
language reference manuals contain information on defining global symbols.)
To pass global symbol information to PATCH, specify the /DEBUG qualifier
when you link your program. (See the appropriate language manual for
complete information on passing global symbols.)

3.1.2

Local Symbols
Local symbols are symbols that are defined in a particular module and can be
accessed only by that module.
You indicate a local symbol in your source program by delimiting it with a
special operator. This operator depends on the language in which your pro¬
gram is written. For example, in VAX MACRO, you define a local symbol by
using a single colon (:) or an equal sign ( = ). (Individual language reference
manuals contain information on defining local symbols.) To pass local symbol
information to PATCH, you must include the debugger when you assemble
or compile and link your program. (See the appropriate language manual and
the VAX/VMS Linker in the VAX/VMS Utilities Reference Volume for more
information on passing local symbols.) When you run PATCH, use the SET
MODULE command to enter local symbol information into the symbol table.

3.1.3

Module Names, Program Section Names, and Routine Names
Module names, program section names, and routine names are always passed
to PATCH unless you specify /NODEBUG and /NOTRACEBACK at link
time. When these qualifiers are specified, no symbol information is passed to
PATCH.
To limit symbol information to only module names, program section
names, and routine names, link your program with the /TRACEBACK
and /NODEBUG qualifiers (these are the default qualifiers).

3.1.4

Universal Symbols
Universal symbols are a subset of the global symbols of a shareable image.
They are the only type of symbol PATCH can reference when patching a
shareable image.
Any global symbol can be a universal symbol. However, you should declare
only a limited subset of global symbols to be universal, because not all sym¬
bols are required for a particular application and partial symbol declaration
reduces system overhead.

PATCH-11

PATCH
Description

To declare a symbol to be universal, specify the option UNI VERS AL= in the
options file when you link your program. For example:
$

LINK/SHAREABLE PROGA.PROGB/OPTIONS
PROGB.OPT

UNIVERSAL=A,B,C

In the above example, the symbols A, B, and C are declared universal in the
shareable image PROGA. The file named PROGB.OPT is the linker options
file in which the universal symbol declarations are contained.
For more information about shareable images and universal symbols, see the
VAX/VMS Linker in the VAX/VMS Utilities Reference Volume.
When using universal symbols in a shareable image, observe the following
guideline: If a symbol is in a transfer vector and has been declared universal
by use of the .TRANSFER directive, the value of the symbol in the shareable
image's user symbol table (UST) is the address of the transfer vector, not the
actual routine address in the image.
Thus, for PATCH to reference locations symbolically in a non-zero-based
shareable image that is position independent, you must specify the symbol as
symbol + <base>

3.1.5

Symbolic Instruction Labels
Symbolic instruction labels are 1- to 31-character symbols having the follow¬
ing characteristics:
•

They must start with an alphabetic character (labels such as 10$ are
invalid for use with PATCH).

•

They can consist of alphanumeric characters, the dollar sign ($) character,
the underscore (_) character, and period (.).

A symbolic instruction label lets you associate a specific name with a par¬
ticular location without knowing the numeric address of the location. This
situation generally arises under three circumstances:
•

You insert, replace, or deposit a series of instructions into the existing
code.

•

PATCH places the new instructions in the current patch area and gener¬
ates branch instructions to and from the patch area to maintain the logical
flow of program execution.

•

You add new instructions, and one of the new instructions references
another new instruction.

PATCH
Description

Because you do not know the exact location of the instruction being refer¬
enced, you can use a symbolic instruction label to reference the location. For
example:
PATCH>INSERT/INSTRUCTION 350
0LD>"TSTL R3'
NEW>'BEQL NONE'
NEW>'MOVL R4.R0'
NEW>1DIVL2 R0.R1'
NEW>'MULL2 R2.R1'
NEW>'NONE:
RET'
NEW>EXIT

Here, a group of instructions is inserted after location 350 by means of a
patch area. Note that the symbolic instruction label NONE is used in the first
instruction to refer to the fifth instruction. The label NONE is used because
the exact placement of these instructions is not known.

3.1.6

Side Effect of Using Symbolic Instruction Labels
Once a symbolic instruction label is assigned a location, the label always
refers to that location, even if the contents of the location are moved. For
example, suppose you have the following code in your program:
TEST.EXE
contents

address

500
502
505

XX:
YY:

TSTL
BEQL
CLRL

R3
LBL3
- (R6)

550
552

LBL3:

CLRL
MOVL

R5
R2.R3

ADDL

R3.R6

555

In this situation, the symbolic instruction label LBL3 is assigned to location
552, and a preceding instruction (BEQL LBL3) refers to LBL3. Later, you dis¬
cover that the CLRL R5 instruction is wrong and you want to replace it with
the instruction CMPL R5,R6. To do this, use the REPLACE/INSTRUCTION
command.
In this example, the new instruction, CMPL R5,R6, requires more bytes
of memory than the old instruction, CLRL R5. Therefore, PATCH will
automatically move the CMPL R5,R6 instruction to the current patch area,
and will replace the CLRL R5 instruction with a branch to the patch area.
However, the branch instruction needed to reroute the logical flow of execu¬
tion to the patch area will also require more bytes than those occupied by the
CLRL R5 instruction. To make room for the branch instruction, the instruc¬
tion following the CLRL R5 instruction will also be moved to the patch area.
The instruction that follows the CLRL R5 instruction is the MOVL R2,R3
instruction, which has the symbolic label LBL3 assigned to its location.

PATCH-13

PATCH
Description

Because the MOVL R2,R3 instruction has a symbolic label, you should not
let PATCH automatically move this instruction to the patch area. Instead,
you should use the REPLACE/INSTRUCTION command to replace both
the CLRL R5 and MOVL R2,R3 instructions. Then, you can create a new
symbolic label for the MOVL R2,R3 instruction. This is shown below.
PATCH>REPLACE/INSTRUCTION 550
0LD>'CLRL R5'
0LD>'LBL3: MOVL R2.R3'

old>exit
NEW>'CMPL R5.R6'
NEW>'NEW.LBL3: MOVL R2.R3'

new>exit
old:
old:
new:
new:
new:
new:
new:
new:

00000550:
CLRL R5
LBL3:
MOVL R2.R3
00000550
BRW 00007800
NOP
00000553
00000554
NOP
00007800
CMPL R5.R6
NEW.LBL3
MOVL R2.R3
00007806
BRW 00000555

During the replacement operation, the following events occur:
•

The CMPL R5,R6 instruction is moved to the current patch area.

•

The MOVL R2,R3 instruction is assigned a new symbolic label and is
moved to the current patch area.

•

A branch instruction to the patch area is inserted into the area left blank
by the replacement of the CLRL R5 instruction and removal of the MOVL
R2,R3 instruction to the patch area.

•

NOP instructions are used to fill the locations not used by the branch
instruction.

As a result of this patch, the symbolic instruction label LBL3 still refers to
location 552, which is the middle of the branch instruction. If you were to
examine LBL3, the following instruction would be displayed:
PATCH>EXAMINE/INSTRUCTION LBL3
LBL3:

MNEGD #01.#01

To correct the problem, you need to change previous instructions that refer to
LBL3. These instructions should now refer to NEW—LBL3 because the MOVL
R2,R3 instruction begins at NEW—LBL3 (location 7803 in the patch area).
Change the reference to LBL3 as shown below.
PATCH>REPLACE/INSTRUCTION

0LD>'BEQL LBL3'
0LD> ' CLRL - (R6) '

old>exit
NEW>'BNEQ LBL2'
NEW>'BRW NEW_LBL3'
NEW>'LBL2: CLRL -(R6)'

new>exit

To correct the reference made to LBL3, the BEQL LBL3 and CLRL -(R6)
instructions were replaced with complementary instructions:

PATCH-14

BNEQ LBL2

Branch if not equal to label LBL2

BRW

Unconditional branch to NEW.LBL3
(location 7803)

NEW.LBL3

PATCH
Description

In this example, you need to use the unconditional branch instruction, BRW,
to direct the flow of execution to location 7803. The unconditional branch
instruction uses a word displacement, which is large enough to hold the
amount by which the program counter is increased. The conditional branch
instruction, BEQL, uses only a byte displacement, which is not large enough
to direct the flow of execution to location 7803.

3.1.7

Symbols Defined with the DEFINE Command
When you run PATCH, you can assign a symbolic name to a location or
value by using the DEFINE command. This command lets you supplement
or override existing symbols in your image for the duration of the PATCH
session. See the DEFINE command in the Commands Section for more
information.

3.2

The PATCH Symbol Table
PATCH maintains a symbol table for global symbols, local symbols, universal
symbols, module names, program section names, routine names, patch area
symbols, and symbols defined with the DEFINE command. Global and local
symbols can be placed in the symbol table if you followed the rules for
passing these symbols during compiling or assembling and linking. If you
did not pass these symbols, PATCH displays one or both of the following
informational error messages when it is invoked:
%PATCH-I-NOGBL, some or all global symbols are not accessible
%PATCH-I-NOLCL, image file does not contain local symls

If you passed symbols from your program correctly, you can place them into
PATCH'S symbol table with one SET MODULE or SET SCOPE command. To
confirm that the symbol table contains the appropriate entries use the SHOW
MODULE command. This command reports the current symbol table status.
See the Commands Section for more information on the SET MODULE, SET
SCOPE, SHOW MODULE and SHOW SCOPE commands.

Pathnames
Some symbols may have several definitions within your image file. To differ¬
entiate the locations defined by these symbols, you must create unambiguous
paths that direct PATCH to the locations to which you want to refer. A path¬
name is a symbolic expression that uniquely defines a location within your
file. It has the following format:
8cope\8ymbol-name±offset-value

scope

Identifies a particular module within your image file in
which PATCH searches for the symbolic name supplied.
The backslash character (\) is a required delimiter.
Supplying a scope is unnecessary when (1) all the symbol
names within your file are unique; (2) the scope is already
set, by use of the SET SCOPE command, to the region
to which you want to refer; or (3) the symbol being
accessed is a global symbol.

PATCH-15

PATCH
Description

symbol-name

Identifies a particular location within your image file.
Symbol names can be global symbols, local symbols, or
symbols you defined with the DEFINE command.
The symbol name is the only element that must always
be supplied in order to find that location.

offset-value

Specifies a positive or negative numeric value, in the
current radix, appended to the symbol name. The offset
value is used to refer to unlabeled locations.

The following example demonstrates the use of a pathname:
PATCH> EXAMINE/INSTRUCTION REM_MOD1\CRM_STRT+1A
REM_MOD 1 \CRM_STRT'♦ 1A:

CLRQ RO

In this example, the EXAMINE/INSTRUCTION command requests that the
contents of location CRM_STRT+1A, in the module named REM_MODl, be
displayed as a VAX MACRO instruction.

3.3

Translating Symbols And Values
PATCH follows a specific sequence of steps to translate an address value to a
symbol or a symbol to an address value. The following sections explain the
algorithms PATCH uses to compute these translations.
3.3.1

Translating Symbols into Address Values
PATCH'S translation of symbolic entries into values is controlled by the
GLOBALS-NOGLOBALS and SCOPE-NOSCOPE modes. The following
steps outline the procedure PATCH uses to perform this translation.
1

First, PATCH compares the symbolic entry with all user-defined symbols,
searching for an exact match. User-defined symbols are symbols you
create with the DEFINE command during a PATCH session.

2 If step 1 fails, PATCH checks the status of the GLOBALS-NOGLOBALS
mode setting. If the mode is set to GLOBALS, PATCH compares the
symbolic entry as you entered it with the symbols in the symbol table,
looking for an exact match. That is, when PATCH searches the symbol
table for a match, it does not prefix the contents of the scope to the
symbolic entry.
3 If step 2 fails, or if the mode is not set to GLOBALS, PATCH checks
the status of the SCOPE-NOSCOPE mode setting. If the mode is set to
SCOPE, PATCH prefixes the contents of the scope setting to the symbolic
entry and searches the symbol table for an exact match.
4 If step 3 fails, or if the mode is not set to SCOPE, PATCH prefixes the
contents of the scope (based on the current PC) to the symbolic entry and
searches the symbol table for an exact match.
5 If step 4 fails, PATCH again checks the status of the GLOBALSNOGLOBALS mode setting. If the mode is set to NOGLOBALS, PATCH
compares the symbolic entry as you entered it with the symbols in the
symbol table, looking for an exact match. That is, when PATCH searches
the symbol table for a match, it does not prefix the contents of the scope
setting to the symbolic entry. (Note that this is the same procedure as step
2, except the mode is set to NOGLOBALS.)

PATCH
Description

If the translation is successful, PATCH evaluates the expression in which the
symbolic entry appears. If the translation fails, PATCH issues the following
error message to indicate that it could not evaluate the symbolic entry:
•/.PATCH-W-NOSYMBOL, no such symbol 'symbolic-entry'

3.3.2

Translating Address Values into Symbols
PATCH'S translation of address values into symbolic entries is governed
by the SYMBOLS-NOSYMBOLS mode. The following steps outline the
procedure PATCH uses to perform this translation:
1

PATCH compares the address value with all user-defined symbols for an
exact match.

2 If step 1 fails, PATCH compares the address value with the global and
local symbol definitions, looking for an exact match.

3 If step 2 fails, PATCH searches all symbol definitions, looking for the
one whose corresponding address value is closest to, but less than, the
specified value. PATCH rejects a symbol definition as being closest to the
address value when the difference between the symbol and the address
value is greater than or equal to hexadecimal 100.
If the translation is successful, PATCH evaluates the expression in which
the address value appears and reports the address value in terms of the
corresponding symbol name. If the translation fails, PATCH still evaluates
the expression in which the address value appears; however, PATCH reports
the address value as a numeric address in terms of the current radix.

3.4

Commands That Affect Symbols and Pathnames
PATCH supplies eight commands used specifically for dealing with symbols
and pathnames.
Command

Description

CANCEL MODULE

Removes local symbols and program section names defined
in the specified module from PATCH'S symbol table

CANCEL SCOPE

Cancels the current symbolic scope and reinstates the
<null> scope

DEFINE

Equates a symbolic name with a value

EVALUATE

Displays the current symbolic definition or definitions of a
value

SET MODULE

Enters local symbols and program section names defined in
the specified module into PATCH'S symbol table

SET SCOPE

Defines the current symbolic scope (by module name or
routine name)

SHOW MODULE

Displays all the modules in the image file being patched
and indicates whether the local symbols contained in those
modules are entered in the PATCH symbol table

SHOW SCOPE

Displays the current symbolic scope

See the Commands Section for more detailed information on each of these
commands.

PATCH-1 7

PATCH
Description

Using Entry and Display Modes
To make referencing locations in an image file more convenient, PATCH
provides eleven entry and display modes. These modes determine how
PATCH interprets commands and displays output. The entry and display
modes are grouped into four functional categories:
•

Context modes control whether PATCH accepts and displays information
as instructions, ASCII text, or data. These modes also control whether
addresses are represented symbolically or numerically.

•

Length modes control the size, in bytes, of data entries and displays.

•

Radix modes determine the base in which PATCH displays and interprets
addresses and data entries.

•

Symbol search modes control the way PATCH performs symbol transla¬
tion.

When you invoke PATCH, the modes are set to NOASCII, NOINSTRUC¬
TION, SYMBOLS, HEXADECIMAL, LONG, NOGLOBALS, and SCOPE.
To change these modes, issue the SET MODE and CANCEL MODE com¬
mands or issue an alternative mode qualifier to a PATCH command. Every
mode setting has a corresponding mode qualifier. For example, both of the
following examples delete an instruction:
PATCH>SET MODE INSTRUCTION
PATCH>DELETE 400='MOVL (R6).(R5)'
PATCH>DELETE/INSTRUCTION 400='MOVL (R6),(R5)'

The difference between the two is that in the first example INSTRUCTION
mode becomes a default setting; in the second example INSTRUCTION
mode is a temporary setting effective only for that command line. The next
command line adheres to the current mode settings. Using an alternative
mode qualifier on a command line overrides the current default setting.
To examine the status of the current modes, issue the SHOW MODE com¬
mand.

Context Modes
The context modes, which enable or disable a mode setting, are listed below.

PATCH-18

•

INSTRUCTION

NOINSTRUCTION

•

ASCII

NOASCII

•

SYMBOLS

NOSYMBOLS

PATCH
Description

4.1.1

INSTRUCTION-NOINSTRUCTION Modes
The INSTRUCTION-NOINSTRUCTION modes control whether data can be
entered and displayed as VAX MACRO instructions (see Section 6.2). The
default setting is NOINSTRUCTION.
When INSTRUCTION mode is set, PATCH does all of the following:
•

Accepts and displays data as VAX MACRO instructions.

•

Accepts and displays instructions in their entirety, and ignores the current
length mode setting. PATCH increments the current address by the
number of bytes occupied by the instruction.

•

Invokes, when you use the REPLACE, INSERT, or DEPOSIT/
PATCH-AREA command, an automatic fitting mechanism that takes
symbolic instructions and fits them into the locations indicated. If the
new instructions are smaller than the available locations, unused bytes are
replaced with no operation instructions (NOPs). If the new instructions
are longer than the available location, PATCH moves them to the current
patch area and inserts branch instructions to and from the patch area.

An instruction string entry must be delimited by quotation marks or apostro¬
phes; the delimiter must not appear within the string.
When NOINSTRUCTION mode is set, PATCH accepts and displays data
according to the current radix, length, and ASCII-NO ASCII mode setting.

4.1.2

ASCII-NOASCII Modes
The ASCII-NO ASCII modes control whether data can be entered and dis¬
played as ASCII data. The default setting is NOASCII. You can use the
ASCII-NOASCII modes only when the NOINSTRUCTION mode is set.
When INSTRUCTION mode is set, PATCH ignores the ASCII-NOASCII set¬
ting and accepts and displays data as VAX MACRO instructions. When ASCII
and NOINSTRUCTION modes are set, PATCH does all of the following:
•

Displays ASCII output strings according to the current length mode.

•

Truncates an ASCII input string if the string exceeds the limit imposed
on it by the current length mode. PATCH truncates input strings by
discarding excessive characters from the right.

•

Ignores the current radix mode when accepting or displaying data.

ASCII data entries must be enclosed within quotation marks (") or apostro¬
phes (').
When NOASCII and NOINSTRUCTION modes are set, PATCH accepts and
displays data according to the current radix and length mode settings.

4.1.3

SYMBOLS-NOSYMBOLS Modes
The SYMBOLS-NOSYMBOLS modes control whether addresses are displayed
by pathnames or symbols, rather than by numeric addresses. The default
setting is SYMBOLS. When SYMBOLS mode is set, PATCH displays all
locations by their respective pathnames or symbols and accepts pathnames as
input.
When NOSYMBOLS mode is set, PATCH displays all locations by their
numeric addresses. You can still enter a pathname as input to PATCH;
however, PATCH displays that location by its numeric address.

PATCH-19

PATCH
Description

4.2 Length Modes
The modes that specify length are BYTE, WORD, and LONG. They denote
how many bytes in memory are available to store a given data item. The
default setting is LONG.
PATCH uses the length modes when the NOINSTRUCTION mode is set.
When the INSTRUCTION mode is set, PATCH ignores the current length
mode.
When NOINSTRUCTION mode is set, PATCH performs two operations:
•

Truncates the most significant bit positions of numeric data that exceed
the boundary imposed on it by the current length mode.

•

Sets only the last length mode specified when you enter conflicting length
modes on a single command line.

4.3 Radix Modes
The modes that specify the radix are OCTAL, DECIMAL, and HEXADECI¬
MAL. They refer to the base by which PATCH translates the entry or display
of numeric data and addresses. The default setting is HEXADECIMAL. The
following rules apply to the radix modes.
•

The radix mode is ignored when the ASCII mode is set.

•

Data is displayed according to the current length mode.

•

Only the last radix mode specified is set when you enter conflicting radix
modes on a single command line.

You can also change the radix modes by specifying a radix operator ("O, ~D,
~X, ~B) before the numeric data. A radix operator controls only the entry that
it accompanies; it has no control over the radix in which PATCH displays a
value.

4.4 Symbol Search Modes
The symbol search modes, which control how PATCH performs symbol
translations, are SCOPE, NOSCOPE, GLOBALS, and NOGLOBALS.
The SCOPE-NOSCOPE modes control whether the contents of the scope
setting are prefixed to a symbolic entry when PATCH tries to locate the
numeric address represented by the symbolic entry. The default setting is
SCOPE.
The GLOBALS-NOGLOBALS modes control the order in which PATCH
searches the symbol table when performing symbol-to-value translations.
If the GLOBALS mode is set, PATCH starts its search by trying to match
the symbolic entry, without prefixing the scope. If NOGLOBALS is set, the
symbolic entry is used as the last pathname in a search. The default setting is
NOGLOBALS.
Note that PATCH follows a certain procedure when performing symbolto-value translations. This procedure is based on the current setting of the
SCOPE-NOSCOPE and GLOBALS-NOGLOBALS modes.

PATCH
Description

Using Patch Area
In many cases, applying a patch to an image file requires adding lines of code
to the file. A convenient technique for adding code is to insert such code into
a storage space called a patch area.
A patch area is read/write virtual memory used to store additional instruc¬
tions or data entries. There are two types of patch area: default patch area
and user-defined patch area.
A default patch area is created by PATCH and is inserted into an image file
following the last normal image section. PATCH will automatically use a
default patch area unless you specify otherwise.
A user-defined patch area, on the other hand, is a patch area that you define
in the source code for your program. It can be located anywhere within the
image file. PATCH will use a user-defined patch area if you issue the SET
PATCH—AREA command during a patch session.
PATCH automatically inserts additional instructions into the current patch
area (either default or user defined) when there is not enough space at the
requested location to insert the code. PATCH then inserts branch instructions
to and from the patch area to maintain the correct flow of program execution.
PATCH will not automatically insert new data into the current patch area.
You can, however, place data into the current patch area by issuing the
DEPOSIT/PATCH-AREA command. Keep in mind that PATCH does not
generate branch instructions to and from the patch area when you use the
DEPOSIT/PATCH—AREA command; you must keep track of and document
the correct flow of program execution when you use that command.

5.1

Patch Area Descriptor
Every patch area, whether a user-defined or default patch area, has a descrip¬
tor associated with it. A patch area descriptor is a record of the current status
of the patch area. The first longword contains the current size (in unused
bytes) of the patch area, and the second longword contains the address of
the first free byte of the patch area. You can observe the status of the current
patch area by issuing the SHOW PATCH-AREA command. For example:
PATCH>SHOW PATCH.AREA
current patch area size:
current patch area address:

00000200
00007800

Any time a command is executed that affects patch area, the patch area
descriptor is automatically updated to reflect the modifications.

5.2

Patch Area Symbols
PATCH uses the symbols PAA through PAZ to indicate the first free byte
of different patch areas used during a patch session. At the start of a patch
session, PATCH assigns the label PAA to the first free byte of the default
patch area. If user-defined patch areas are also used, PATCH assigns the
labels PAB through PAZ to represent the first free byte of these patch areas.
PATCH assigns these symbols in the order in which the user-defined patch
areas are accessed during a patch session.

PATCH-21

PATCH
Description

The symbols PAA through PAZ are called patch area symbols and are
reserved for use by DIGITAL. You are advised not to use these symbols.
However, you can create your own patch area symbols using the ALIGN
command. This command lets you assign symbolic names to the starting
address of patches in the default patch area and in all the user-defined
patch areas. See the ALIGN command in the Commands Section for more
information.

5.3

Default Patch Area
The default patch area is area automatically supplied by PATCH. Generally,
the default patch area is expandable. It is limited by available disk space
during PATCH execution and the value of the SYSGEN virtual page count
parameter at run time.
PATCH allocates the default patch area one page at a time, as necessary.
For example, if you are inserting additional instructions into the image file,
PATCH allocates another page of the default patch area if the existing default
patch area is too small to accommodate the new instructions.
By convention, whenever you patch an image file and the patches require
the use of a patch area, those patches are placed in the default patch area.
However, the default patch area cannot be used to store patches for device
driver images and position-dependent shareable images that have been linked
with other images.
If you need to patch a device-driver image or a position-dependent shareable
image that has been linked with other images, you should use a user-defined
patch area.

5.4

User-defined Patch Area
A user-defined patch area is an area you define in the source code. This patch
area is located within the boundaries of the image file; PATCH does not
extend the length of the image file to accommodate a user-defined patch area.
Also, a user-defined patch area is of a fixed size; PATCH cannot increase the
size of a user-defined patch area to accommodate additional patches.
You should use a user-defined patch area to store additional code when
patching device-driver images and position-dependent shareable images.
A device-driver image contains, at the start of the image, a location that
defines the total length of the driver. When the device driver is loaded,
the driver loader looks at this location to determine the amount of space to
allocate to the device-driver. The fact that PATCH extends the device-driver
image when default patch area is used means that the total length of the
device-driver image increases. However, PATCH does not recognize the
location that contains the length of the device-driver, nor can PATCH modify
the contents of that location if it extends the device-driver image. Thus, a
subsequent running of a device driver that uses default patch area causes the
patch area to be truncated.

PATCH-22

PATCH
Description

5.4.1

Creating and Accessing a User-Defined Patch Area
To create a user-defined patch area, define global symbols in your source
program to indicate the size of the patch area, the location of the patch
area, and optionally the location and contents of the patch area descriptor.
When you issue the SET PATCH-AREA command during a patch session,
subsequent patches will be placed in the user-defined patch area, rather than
in the default patch area.
The SET PATCH—AREA command can be used with or without the
/INITIALIZE qualifier. However, the way you define the patch area in
your source program should be compatible with the form of the SET
PATCH-AREA command you plan to use.
See the SET PATCH-AREA command in the Commands Section for more
information.

5.4.2

Terminating the Use of a User-Defined Patch Area
To terminate the use of a user-defined patch area, issue the CANCEL
PATCH-AREA command that resets the current patch area to the default
patch area.
You can also change the patch area from one user-defined patch area to
another user-defined patch area by issuing the SET PATCH-AREA command.

5.5

Commands That Affect Patch Area
The PATCH commands that affect patch area are described below.
Command

Description

ALIGN

Aligns the first free byte of the current patch area
on the specified boundary and defines a symbol for
that address.

CANCEL PATCH-AREA

Cancels the use of the current user-defined patch
area and reverts to the use of the default patch area.

DEPOSIT/PATCH_AREA

Deposits data or VAX MACRO instructions in the
current patch area.

INSERT/INSTRUCTION

Inserts one or more VAX MACRO instructions into
the current patch area.

REPLACE/INSTRUCTION

Stores new instructions in patch area if they occupy
more bytes in memory than the instructions being
replaced.

SET PATCH-AREA

Establishes a user-defined patch area as the current
patch area. Used with the /INITIALIZE qualifier,
this command creates a patch area descriptor and
establishes a user-defined patch area as the current
patch area.

SHOW PATCH-AREA

Displays the patch area descriptor of the current
patch area.

Each of these commands is explained in the Commands Section.

PATCH-23

PATCH
Description

5.5.1

DEPOSIT/PATCH—AREA Command
The DEPOSIT/PATCH-AREA command uses the patch area to store addi¬
tional instructions or data; however, PATCH does not automatically generate
branch instructions to and from the patch area when you deposit the new
data. You must insert the branch instructions manually. You must also re¬
calculate the relative displacements of all branch-type instructions affected by
the insertion of new data or instructions.

5.5.2

INSERT/INSTRUCTION Command
When you use the INSERT/INSTRUCTION command, PATCH automatically
stores the new instructions in the patch area and generates unconditional
branch instructions to reroute the logical flow of execution to the patch area,
then back to the inline code. You can use the INSERT command only for
instructions, not for data.
Occasionally, when you insert one or more new instructions into your code,
the following events may occur:
•

A branch-type instruction is moved to the current patch area.

•

The patch area is far enough away to prevent the branch-type instruction
from reaching its destination.

When these events occur, the INSERT/INSTRUCTION command recalculates
the relative displacement of the branch-type instruction to allow the branch to
reach its destination. For example, suppose the insertion of a new instruction
causes the BRB 200 instruction to be moved to the patch area. However, once
the BRB 200 instruction is in the patch area, the byte displacement is not
large enough to reach location 200. The INSERT/INSTRUCTION command
then recalculates the byte displacement to allow the branch to succeed. If
necessary the BRB instruction is changed to a BRW or JMP instruction.
Be aware that PATCH always completes a patch with a branch or a jump
instruction to the inline code, even if the last instruction of the patch is an
unconditional branch or jump instruction.
The INSERT/INSTRUCTION command may cause an instruction identified
by a symbolic label to be moved to the patch area. If this occurs, the symbolic
label still points to the original location of the instruction. Therefore, you
must change any instructions in the program that use the symbolic label to
refer to the instruction that was moved.

5.5.3

REPLACE/INSTRUCTION Command
When you use the REPLACE/INSTRUCTION command, PATCH automati¬
cally stores the new instructions in the patch area only if the new instructions
occupy more bytes in memory than the instructions being replaced. If the
patch area is used, PATCH generates branch instructions to and from the
patch area to maintain the correct flow of program execution.
When you replace numeric or ASCII data, the new data is truncated if it
exceeds the length of the data that it is to replace. (That is, the patch area is
not used.)
As with the INSERT/INSTRUCTION, the REPLACE/INSTRUCTION com¬
mand can also cause a branch-type instruction to be moved to the patch area.
If the new location of the branch-type instruction is too far away to allow
the branch to reach its destination, the REPLACE/INSTRUCTION command
recalculates the relative displacement of the branch-type instruction to allow
the branch to reach its destination.

PATCH
Description

Be aware that PATCH always completes a patch with a branch or a jump
instruction to the inline code, even if the last instruction of the patch is an
unconditional branch or jump instruction.
The REPLACE/INSTRUCTION command may cause an instruction identified
by a symbolic label to be moved to the patch area. If this occurs, the symbolic
label still points to the original location of the instruction. Therefore, you
must change any instructions in the program that use the symbolic label to
refer to the instruction.

Rules of Syntax
The following section includes the syntax rules of which you must be aware
when using PATCH.

6.1

Entering ASCII Data Strings
To enter ASCII data strings, specify either the /ASCII mode qualifier or set
the mode to ASCII.
When you enter ASCII data strings to PATCH, they must be enclosed within
matching quotation marks (") or apostrophes (7). By allowing either quota¬
tion marks or apostrophes to be string delimiters, you can include one or the
other delimiter as part of the input string. For example, if you want to insert
the ASCII text 7AL7, you would type
PATCH>DEPOSIT/ASCII 500="

'AL'"

You cannot delimit an ASCII data string with the same delimiter as the one
you include as part of the string.
When entering an ASCII data string, PATCH will truncate the string if it
exceeds the length imposed on it by the current length mode setting. PATCH
truncates the string by discarding excessive characters from the right.

6.2

Entering VAX MACRO Instructions
To enter VAX MACRO instructions, either specify the /INSTRUCTION mode
qualifier or set the INSTRUCTION mode.
The rule for the use of quotation marks (") and apostrophes (7) described
for entering ASCII data strings also applies to entering VAX MACRO in¬
structions. An instruction string entry must be delimited by quotation marks
or apostrophes and not a combination of both, and the delimiter must not
appear within the string.
To enter operands with displacements, you must prefix the operand with B*,
W~, or L~. For example:
PATCH>DEP0SIT 500='ADDL2 B~4(R0),R8'

Here, PATCH deposits code for this instruction into sequential addresses
starting with 500.
When instructions assembled with forced-immediate-addressing mode (F#)
are displayed, they are displayed as #'xxxxx' where xxxxx is the size of a byte,
word, or longword, depending on operand data type.

PATCH-25

PATCH
Description

The following entries show the difference between immediate-mode and
forced-immediate-mode addressing:
MOVW
MOVW
MOVL
MOVL
.END

#1,R0
I~#l,R0
#1,R0
I~#l,R0

See the VAX MACRO and Instruction Set Reference Volume for more informa¬
tion.

VAX MACRO Instructions With The Same Opcodes
In VAX MACRO, different instructions can generate the same opcode. For
example, MOVAL and MOVAF both generate the hexadecimal opcode DE.
PATCH, however, displays only one instruction for any of the opcodes that
can be produced by multiple instructions. For example, if you use MOVAF in
your source program, PATCH displays MOVAL.
The instructions in the table below have the same opcodes.
Instructions with
Equivalent Opcodes

Instruction Displayed
by PATCH

Opcode

BCC

BGEQU

BLSSU

BEQL

BNEQ

CLRQ

CLRL

CLRO

7CFD

MOVAQ

BGEQU

BCS
BLSSU
BEQL
BEQLU

BNEQ
BNEQU

CLRD
CLRG
CLRQ

CLRF
CLRL
CLRH
CLRO
MOVAD
MOV AG
MOVAQ

PATCH-26

PATCH
Description

Instructions with
Equivalent Opcodes

Instruction Displayed
by PATCH

Opcode

MOVAF

MOVAL

MOVAO

7EFD

PUSHAQ

PUSHAL

PUSHAO

7FFD

MOVAL
MOVAH
MOVAO
PUSHAD
PUSHAG
PUSHAQ

PUSHAF
PUSHAL
PUSHAH
PUSHAO

All two-operand instructions are displayed as xxx2. For example, ADDF is
displayed as ADDF2.

6.3

Entering Numeric Data
When you enter numeric data to PATCH, the mode qualifiers
/NOINSTRUCTION and /NOASCII must be specified or the
NOINSTRUCTION and NOASCII modes must be set. In addition, do not
enclose the data within matching quotation marks or apostrophes.
You can, however, enter numeric data concurrently with instructions provided
you are using the assembler directives listed below:
.BYTE
.WORD
.LONG

The following example illustrates such an insertion:
PATCH>DEPOSIT/PATCH_AREA/INSTRUCTION
NEW>'TSTL R4'
NEW>'BEQL LBL3'
NEW>'MOVL B~LBL2.R0'
NEW>'LBL1: RET'
NEW>'LBL2: .LONG 1.0'
NEWVLBL3: MOVL LBL2+4.R0'
NEW>'BRB LBLI'

PATCH-27

PATCH
Description

Precede any hexadecimal number starting with an alphabetic character (that
is, A through F) with a 0. Otherwise, PATCH will interpret the hexadecimal
number as a symbol. For example, enter the numeric string FFA as shown in
this example:
PATCH>REPLACE 200=000000FA
NEW>0FFA
new>exit
old:
000000FA
new:
00000FFA

6.4

Delimiting Parameter Values
The equal sign ( = ) is used to separate an address expression from a data
entry or to separate a symbol name from a value. Certain commands require
an equal sign, unless you enter their parameters after PATCH prompts.
These commands are DEFINE, DELETE, DEPOSIT, INSERT, REPLACE, and
VERIFY.
Use a comma to separate parameter values in commands that can take
multiple parameters.

Entering Comments
To insert comments, prefix them with the exclamation point (!) character.
When PATCH reads an exclamation point, it ignores all following information
on that line. The only restriction on entering comments is that a comment
cannot appear on the same line as a command string that uses a continuation
character (-). Comments will be entered into the journal file.

6.5

Special Operators For Arithmetic Expressions
This section describes the special operators that PATCH recognizes in arith¬
metic expressions.
Operator

Name

Function

Addition operator

Unary plus sign or addition ope
ator in arithmetic expressions

Subtraction operator

Unary minus sign or subtrac¬
tion operator in arithmetic
expressions

•

Multiplication operator

Multiplication operator in arith¬
metic expressions

Division operator

Division operator in arithmetic
expressions

Shift operator

Arithmetic shift operator

< >

Priority operators

1. Priority operators
2. Bit field delimiters for the
EVALUATE command

PATCH-28

Radix operator

Radix operator for hexadecimal
notation

PATCH
Description

Operator

-o

6.6

Name

Function

Radix operator

Radix operator for decimal
notation

Radix operator

Radix operator for octal notation

Radix operator

Radix operator for binary nota¬
tion

Special Operators For Addressing Locations
This section describes the special operators that PATCH recognizes for
locating addresses and gives examples of how to use these operators.
Name

Operator

Function

Current location operator

Refers to the location last
specified; that is, the current
location. This value remains
the same until you reference a
new location

Previous location operator

Refers to the location that
precedes the last location
specified; subtract, from the
current location, the number
of bytes indicated by the
length mode

Range operator

Used to specify a range
of locations for the CHECK
ECO, CHECK NOT ECO,
EVALUATE, and EXAMINE
commands

Backslash operator

Refers to either the contents
of the location specified in a
branch instruction or the value
stored in an address specified
in the previous EXAMINE
command

PATCH-29

PATCH
Command Qualifiers

COMMAND
QUALIFIERS

This section describes the optional qualifiers to the PATCH command that
allow you to override default file specifications and process selected patches
in command procedures.

PATCH
/ABSOLUTE

/ABSOLUTE
Patches a file at absolute virtual addresses.

FORMAT

/ABSOLUTE

DESCRIPTION

The /ABSOLUTE function allows a user to patch any file (not just image files)
at absolute virtual addresses relative to the beginning of the file. This feature
allows replacement of existing data with new data of the same length. If the
data is smaller than that of the original data, PATCH uses the appropriate fill
character for the mode in use. For example, if the current mode is instruction
mode, a NOP is used for fill; if it is data (numeric or ASCII) mode, a NULL
is used for fill. Any PATCH operation that results in a data replacement
longer than the length of the original data generates an error message and
terminates the command in progress; either the PATCH or DCL prompt is
then displayed, whichever is appropriate.
Also, note that there is no default patch area, and none will be created,
because of the tendency to corrupt a file. Patch area is meaningless in other
than an image file.
If you patch a file in absolute mode, remember that that there are no symbols
available to assist you in locating data locations. You must exercise great care
to ascertain that the correct locations are modified.
Most PATCH commands will work in their normal fashion. However,
only REPLACE and DEPOSIT should be used for write operations; other
commands are acceptable for read operations. Commands that attempt to
expand the file, such as ALIGN and INSERT, should be avoided because they
will probably corrupt the file. (These commands will be trapped by PATCH
and an error message will be issued indicating that the replacement data must
not exceed the length of the original data.)
File attributes are propagated from the original input file to the output file.
These include ALQ, TYPE, MRS, RAT, RFM, and RAC.

EXAMPLE
$ PATCH/ABSOLUTE IMAGE.EXE
PATCH>EX/INS 604
00000604:
BBSS
#07.R1.00000608
PATCH>REPLACE/INS 604='BBSS #07.Rl.0608'
•BBSS #07.Rl.0608'
NEW>
•CLRL RO'
NEW>
NEW> EXIT
00000604:
BBSS
#07.Rl.00000608
old:
%PATCH-E-DATT00LNG, length of new data may not exceed length of old data
PATCH>EX/INS 684
00000684:
M0VB
#01.(R5)+
PATCH>REPLACE/INS 684='M0VB #01,(R5)+'
NEW>
'MOVB #02,(R5)+'
NEW> EXIT
old:
00000684:
MOVB
#01,(R5)+
new:
00000684:
MOVB
#02,(R5)+
PATCH>EX/INS 687
00000687:
MOVB
#00,(R5)+
PATCH>DEPOSIT/INS 687

PATCH-31

PATCH
/ABSOLUTE

NEW> 'CLRB (R5)+'
NEW> EXIT
old:
00000687:
MOVB
#00,(R5)+
new:
00000687:
CLRB
(R5)+
PATCH>lNSERT/INS 68D
0LD> 'MOVB #10,(R5)+'
NEW> 'MOVB #20,(R5)+'
NEW> EXIT
old:
0000068D:
MOVB
#10,(R5)+
'/.PATCH-E-DATTOOLNG, length of new data may not exceed length of old data
PATCH>UPDATE
7.PATCH-I-WRTFIL, updating image file DISK$STARW0RK01:[NASR.PATCH]IMAGE.EXE;2
PATCH>EXIT

An example of the /ABSOLUTE qualifier with
/NEW_VERSION as the default. Note the error messages returned when
the command tries to expand the file. The example for the /NEW_VERSION
qualifier in the Command Qualifiers section shows the use of /ABSOLUTE
with /NONEW_VERSION.

PATCH—32

PATCH
/JOURNAL

/JOURNAL
Overrides the default journal file specification.

FORMAT
qualifier value

/JOURNAL

/=;file-spec]

file-spec
Specifies the alternate journal specification. If you omit fields in the file
specification, PATCH supplies the following default values:
Field

Default Value

Device and directory

Defaults of current process

File name

Name of input image file

File type

JNL

Version

No wildcard characters are allowed in the file specification.
Subsequent PATCH sessions append information to the journal file, rather
than create a new version of this file.

DESCRIPTION By default, PATCH creates a journal file with a file specification that consists
of the current defaults. Use the /JOURNAL qualifier when you want to
specify an alternate file specification.

EXAMPLE
$

PATCH AVERAGE/J0URNAL=DB1:[JACKSON]TEST

This command invokes PATCH for an interactive PATCH session with the
image file AVERAGE.EXE. The /JOURNAL qualifier requests that the journal
file be named TEST.JNL;1 and that it be created in the DBl:[JACKSON]
directory.

PATCH-33

PATCH
/NEW—VERSION

/NEW—VERSION
Controls whether a new version of the patched file is created or the
contents of the existing file are modified in place.

FORMAT

/[NO]NEW_VERSION

DESCRIPTION The /NEW_VERSION qualifier is used in conjunction with the /ABSOLUTE
qualifier to control whether a new version of the patched file is created or the
contents of the existing file are modified in place. /NEW—VERSION is the
default. If /NONEW—VERSION is selected, the PATCH command UPDATE
will act as a checkpoint operation; that is, all modifications made to the file
are written back to the file instead of waiting until image exit. If /ABSOLUTE
is not specified with /NONEW_VERSION, /NONEW_VERSION is ignored,
that is, a new version of the file will be created. /NONEW_VERSION will
need to be used when patching large data files when there is not enough disk
space to create a new version of the patched file.

Note: If /NEW_VERSION is specified, the file will be overwritten. No attempt
on the part of the user, including pressing CTRL/Y, will prevent this
result. Therefore, you should have a back up copy of the file before
making any attempt to patch it.
PATCH will always issue an informational message at image exit, indicating
that the file is being overwritten.

EXAMPLE
$ PATCH/ABSOLUTE/NONEW.VERSION LIN.COM
PATCH>EX/ASCII 57
00000057:
'MANA'
PATCH>REPLACE/ASCII 57='MANA'
NEW>
'mana'
NEW>
'test'
NEW>
exit
00000057:
'MANA
old:
y*PATCH-E-REPLACEERR, replacement value too large for location
PATCH>replace/a8Cii 57='MANA'
NEW>
'mama'
NEW>
exit
old:
00000057:
'MANA'
new:
00000057:
'mana'
PATCH> EX/ASC11 24
00000024:
'F$M0'
PATCH>INSERT/ASCII 24='F$M0'
NEW>
'test'
NEW>
exit
%PATCH-E-INVCMD, invalid command
PATCH>UPDATE
•/.PATCH-I-OVERLAY. DISK$STARW0RK01: [NASR. PATCH] LOGIN. COM; 1 being overwritten
PATCH>EX 68:75
00000068:
4349544F
0000006C:
58542E45
00000070:
00010054
00000074:
00100024
PATCH>REPLACE 68
0LD> 4349544F
0LD> 58542E45

PATCH
/NEW—VERSION

00010054
OLD>
EXIT
OLD>
6369746F
NEW>
68642E65
NEW>
00010074
NEW>
EXIT
NEW>
00000068
old
0000006C
old
00000070
old
00000068
new
new
0000006C
00000070
new
PATCH> EX/ASCII 68

4349544F
58542E45
00010054
6369746F
68642E65
00010074

00000068:
'otic'
PATCH> UPDATE
'/.PATCH -1 - OVERLAY, DISK$STARW0RK01: [NASR. PATCH] LOGIN. COM; 1 being overwritten
PATCH>EXIT
'/.PATCH -1 - OVERLAY, DISK$STARW0RK01: [NASR. PATCH] GIN. COM; 1 being overwritten
$

Example of a PATCH/ABSOLUTE/NONEW_VERSION command. Note
the error messages that are returned when the command tries to expand the
file, and when the commands UPDATE and EXIT are performed, that is,
(file) "being overwritten." The example for the /ABSOLUTE qualifier in the
Command Qualifiers section shows the use of /ABSOLUTE with /NEW_
VERSION as the default.

PATCH—35

PATCH
/OUTPUT

/OUTPUT
Overrides the default output image file specification.

FORMAT
qualifier value

/OUTPUT /=file-spec]

file-spec
Indicates the output image file specification.
If you omit fields in the file specification, PATCH supplies the following
default values:
Field

Default Value

Device and directory

Defaults of current process

File name

Name of input image file

File type

EXE

Version

One greater than the most recent copy of the input
image file

No wildcard characters are allowed in the file specification.

DESCRIPTION

By default, PATCH creates an output file with a file specification that consists
of the current defaults. Use the /OUTPUT qualifier when you want to specify
an alternate file specification.
The output image file is created only when you issue the PATCH command
UPDATE at the end of the PATCH session. You can issue multiple UPDATE
commands in a single session. The first UPDATE command creates the
output image file; subsequent UPDATE commands overwrite this file.

EXAMPLE
$ PATCH PAYROLL/JOURNAL=TESTER/OUTPUT=TESTER

This command invokes PATCH for an interactive PATCH session with the
image file PAYROLL.EXE. The journal file and the output image file created
by this session are named TESTER.JNL;1 and TESTER.EXE, respectively, and
reside in the current default device and directory.

PATCH-36

PATCH
/UPDATE

/UPDATE
Processes only those patches associated with the specified ECO
levels.

FORMAT
qualifier value

/UPDATE [=(eco-level[, ...])]

eco-level
Specifies the ECO level of the patches. If you specify more than one ECO
level, you must separate the ECO levels with commas and enclose the list in
parentheses.

DESCRIPTION

The /UPDATE command qualifier lets you apply to an image file only the
patches that correspond to the ECO levels specified with /UPDATE. Typi¬
cally, you use the /UPDATE qualifier when processing a PATCH command
procedure. However, you can also use it when invoking PATCH for an
interactive patching session.
When you specify the /UPDATE qualifier, the PATCH command file speci¬
fication denotes either a command procedure that contains the patches to be
processed or an image file to which certain patches are to be applied. When
the file specification denotes a command procedure, the /UPDATE qualifier
must precede the file specification on the command line. When the file spec¬
ification denotes an image file, the /UPDATE qualifier can precede or follow
the file specification. In either case, the file specification is required.
If PATCH encounters an ECO level in a command procedure that does not
match the ECO level specified on the /UPDATE qualifier, PATCH ignores
the ensuing patch but displays a message. Whenever you omit the optional
ECO levels, PATCH responds by processing all patches submitted.

Processing Selected Patches in Command Procedures
PATCH assumes that the file is a command procedure if the file specification
is preceded by an at sign (@). PATCH reads the command procedure and
parses every command in the command procedure. However, PATCH
executes only those commands in patches corresponding to the ECO levels
specified with the /UPDATE qualifier. The first entry in the command
procedure is always the name of the image file to which the patches are to be
applied.
Do not use the /UPDATE qualifier to apply selected patches if the command
procedure contains user-defined symbolic references. When PATCH parses
each command line to look for the patches specified by the /UPDATE
qualifier, PATCH may be unable to resolve symbolic references. If this
occurs, PATCH terminates the command procedure.
You can, however, use ECO commands to apply selected patches in command
procedures that contain user-defined symbols.

PATCH-37

PATCH
/UPDATE

When PATCH executes the command procedure, it displays on the terminal
the following information:
•

The name of the image file to be patched

•

The PATCH introductory message

•

The patches applied to the image file

•

The relevant ECO error messages
•

ECO levels specified with /UPDATE, but already applied to the image
file

•

ECO levels present in the command procedure, but not specified with
/UPDATE

The first example below shows how PATCH executes selected patches in the
command procedure TEST1.COM.

EXAMPLES
□

$ PATCH/UPDATE=(10,12) <8 [JOHNSON.FORTRAN]TEST1.COM [MATTHEWS.F0RTRAN3PR0GB.EXE
PATCH

VERSION 4-00

15-Apr-1984

DRM1:
0EFDE4800
old:
DRM1:
0EFDE4800
new:
DRM1:
00000000
'/♦PATCH-I-WRTFIL, updating image file DB1:[MATTHEWS.FORTRAN]PROGB.EXE;8
XPATCH-I-UPDATE, patch with eco 11 ignored due to update qualifier
AMSTR+50:
6B5C4005
old:
AMSTR+50:
6B504005
new:
AMSTR+50:
00000000
%PATCH-I-WRTFIL, updating image file DB1:[MATTHEWS.FORTRAN]PR0GB.EXE;8

This PATCH command executes the command procedure TEST1.COM, which
resides in the directory [JOHNSON.FORTRAN]. The /UPDATE qualifier
requests that only the patches identified by the ECO levels 10 and 12,
contained in TEST1.COM, be applied to the image file PROGB.EXE in the
directory [MATTHEWS.FORTRAN]. The display indicates that the patches
specified with /UPDATE were successfully applied to PROGB.EXE and
reports that the patch identified by ECO level 11 was not applied because
that ECO level was not specified with the /UPDATE qualifier.
Note that when you execute command procedures, the /UPDATE qualifier
must precede the name of the command procedures.
If you do not include the /UPDATE qualifier, PATCH applies all patches in
the command procedure, unless it encounters an ECO level that has already
been applied to the image file.

PATCH-38

PATCH
/UPDATE

Processing Selected Patches Interactively
When you include the /UPDATE qualifier with the input image file, PATCH
processes only those patches represented by the ECO levels specified with
/UPDATE. If, while editing the image file, you define an ECO level not
specified with the /UPDATE qualifier, PATCH ignores the subsequent
commands and displays an informational error message. For example:
@

$ PATCH/UPDATE=(2,4) CIRCLE
PATCH

VERSION 4-00 15-Apr-1984

PATCH>SET ECO 2

PATCH>UPDATE

PATCH> SET ECO 3
'/.PATCH-I-UPDATE, patch with eco level 3 ignored due to update qualifier
PATCH> SET ECO 4

In the above example, PATCH allows processing of the patch identified by
the ECO level 2; however, when you try to define ECO level 3, PATCH
displays a message indicating that the patch cannot be applied because it was
not specified with /UPDATE.
Note also that if you specify an ECO level with /UPDATE, but do not set
that ECO level during the PATCH session, PATCH issues an informational
error message when you exit from PATCH.

PATCH-39

PATCH
/VOLUME

/VOLUME
Places the output file on a specified relative volume number of a
multivolume set.

FORMAT
qualifier value

/VOLUME =[n]
n
Specifies the relative volume number of a multivolume set.

DESCRIPTION

The /VOLUME command qualifier lets you specify a relative volume number
where the output file will be placed.
If you specify /VOLUME without a number, the number defaults to the
relative volume number of the input image file. If you do not specify the
/VOLUME qualifier, the output image file is placed in the first available
position within the multivolume set.

EXAMPLE
$ PATCH/V0LUME=2 PAYROLL.EXE

This command creates an output file in relative volume 2.

PATCH-40

PATCH
Commands

COMMANDS

This section describes the PATCH commands.

PATCH-41

PATCH
ALIGN

ALIGN
Allocates space for the default patch area if the image file has not
been patched previously.
If the image file has been patched previously, the ALIGN command
advances the starting address of the current patch area to the first
free byte aligned on the requested boundary (byte, word, longword,
quadword, or page) and equates a symbolic name to that address.
Once you define the symbolic name, you can use it in place of the
address it denotes.

FORMAT
command
parameter

ALIGN

symbol-name

symbol-name
Specifies a 1- to 31-character symbol. It must start with an alphabetic charac¬
ter, and consist of alphanumeric characters, dollar signs ($), underscores (_),
and/or periods (.).
If you specify a symbol name for an address that has been previously as¬
signed a symbol name, the newest symbol name takes precedence.

command
qualifiers

/BYTE
Defines the symbol as the first free byte of the current patch area. If the
current patch area has not been used previously, PATCH allocates the first
block of default patch area.

/WORD
Advances the starting address of the current patch area to the first free word
boundary.

/LONG
Advances the starting address of the current patch area to the first free
longword boundary.

/QUAD
Advances the starting address of the current patch area to the first free
quadword boundary.

/PAGE
Advances the starting address of the current patch area to the first free page
boundary.

DESCRIPTION When you specify ALIGN, none of the patch area between the old patch area
address and the aligned patch area address is cataloged by PATCH. You must
keep a record of the disjointed patch area for it to be used.

PATCH-42

PATCH
ALIGN

After an alignment has been made, the patch area string descriptor is updated
to reflect the modifications. If the patch area is already aligned on the
specified boundary, no update is performed.
You must enter only one alignment qualifier for each ALIGN command.

EXAMPLES
Q

PATCH>ALIGN/QUAD M0D_1
old patch area size:
old patch area address:
new patch area size:
new patch area address:
symbol " M0D_l" defined as

0001E3
0000081D
000001E0
00000820
00000820

The ALIGN command requests that the patch area starting address be ad¬
vanced to the first free quadword boundary in the current patch area and that
the symbol MOD_l be equated with that address. The display shows the old
and new patch area status.
0

patch>align/byte patarea
old patch area size:
old patch area address:
new patch area size:
new patch area address:
symbol " PATAREA" defined as

00000000
00000000
00000200
000000
00001800

This ALIGN command allocates the first block for the default patch area and
assigns the symbol PATAREA to its new starting address.

PATCH-43

PATCH
CANCEL MODE

CANCEL MODE
Cancels the mode settings that you defined using the SET MODE
command.

FORMAT

CANCEL MODE

command
parameters
command
qualifiers

None.
None.

DESCRIPTION Use CANCEL MODE to control the syntax of commands you enter and

the values PATCH displays. CANCEL MODE cancels the current mode
settings and reinstates the initial default mode settings—NOINSTRUCTION,
NOASCII, SYMBOLS, HEXADECIMAL, LONG, NOGLOBALS, and SCOPE.

EXAMPLE
PATCH>SH0W mode
modes:
nosymbols. instruction, ascii, scope, globals, decimal word
PATCH>CANCEL MODE
PATCH>SHow MODE
modes:
symbols, noinstruction, noascii, scope, noglobals, hexadecimal long

The first SHOW MODE command displays the current mode status. The
CANCEL MODE command requests that the initial default mode settings
be reinstated. The second SHOW MODE command confirms that the initial
default settings have been reestablished.

PATCH-44

PATCH
CANCEL MODULE

CANCEL MODULE
Removes local symbol information from the PATCH symbol table.

FORMAT
command
parameter

CANCEL MODULE module-name [, ... 7
module-name
Specifies the name of one or more modules whose local symbols are to be
removed from the symbol table.
Do not specify a module name if you include the /ALL qualifier.

command
qualifier

/ALL

DESCRIPTION

Use CANCEL MODULE to remove local symbol information from the
PATCH symbol table; this command does not remove global symbols, patch
area symbols, universal symbols, or symbols you defined with the DEFINE
command. Once the module's local symbols have been removed, they cannot
be used to reference locations. To reenter local symbols into the PATCH
symbol table, issue the SET MODULE command.

Removes all local symbol information from the symbol table.

To remove all local symbol information from the symbol table, specify the
/ALL qualifier.
If the scope is the name of the module that you specify with the CAN¬
CEL MODULE command, the contents of the scope is reset empty string
(<null>).

EXAMPLES
Q

PATCH>SHOW MODULE
module name
LOVAT

symbols
yes

size
180.

1.
EEA4.

total modules:
remaining size:
PATCH>CANCEL MODULE
nam>lovat
nam>exit

The SHOW MODULE command indicates that the local symbols contained
in the module named LOVAT are entered in the symbol table. The CANCEL
MODULE command purges the symbol table of the local symbols contained
in LOVAT.
B

PATCH>CANCEL MODULE/ALL

This CANCEL MODULE command removes all local symbol names entered
in the symbol table.

PATCH—45

PATCH
CANCEL MODULE

PATCH>set SCOPE circle

PATCH>cancel MODULE circle
PATCH>show scope
SCOPE: <null>

The SET SCOPE command establishes the module named CIRCLE as the
current scope setting. Later, the CANCEL MODULE command removes
all local symbols in CIRCLE from the symbol table and, at the same time,
sets the scope to the empty string (<null>). The SHOW SCOPE command
confirms the new scope setting.

PATCH—46

PATCH
CANCEL PATCH-AREA

CANCEL PATCH-AREA
Resets the current patch area from a user-defined patch area back to
the default patch area.

FORMAT

CANCEL PATCH-AREA

command
parameters
command
qualifiers

None.

DESCRIPTION

Use CANCEL PATCH—AREA to reset the current patch area from a userdefined patch area to the default patch area. Any patch area needed thereafter
will be taken from the default patch area until the next SET PATCH—AREA
command is issued.

None.

The CANCEL PATCH_AREA command is used primarily when you have
issued the SET PATCH—AREA command to establish a user-defined patch
area as the current patch area. After you have inserted the necessary patch
information into that area, type CANCEL PATCH—AREA to resume use of
the default patch area.
You must specify the CANCEL PATCH—AREA command if you have de¬
fined, and are using, a user-defined patch area that is too small to store the
patches you want to insert. Failing to use the CANCEL PATCH—AREA
command causes PATCH to return an error message indicating that it cannot
insert the patch into the patch area.

EXAMPLE
PATCH> SET PATCH_AREA AREA1

PATCH> CANCEL PATCH.AREA

The SET PATCH—AREA command establishes the user-defined patch area
AREA1 as the current patch area. After depositing the necessary data into
AREA1, the CANCEL PATCH—AREA command is issued to resume use of
the default patch area.

PATCH-47

PATCH
CANCEL SCOPE

CANCEL SCOPE
Cancels the current symbolic scope.

FORMAT

CANCELSCOPE

command
parameters
command
qualifiers

None.

DESCRIPTION

Use CANCEL SCOPE to cancel the current symbolic scope and revert to an
empty string ( <null> ).

None.

EXAMPLE
PATCH>SHOW scope
SCOPE: MODI
PATCH>CANCEL SCOPE
PATCH>SHOW SCOPE
scope: <null>

The first SHOW SCOPE command indicates that the scope is set to the
module named MODI. The CANCEL SCOPE command cancels the scope
setting and reverts to the empty string (<null>). The second SHOW SCOPE
command confirms that the contents of the scope is an empty string.

PATCH—48

PATCH
CHECK ECO

CHECK ECO
Verifies that the patches represented by the specified ECO levels
have been applied. Use this command before applying a patch.

FORMAT

CHECK ECO

eco-level[:eco-level][, ... 7

eco-level

command
parameter

Indicates one or more ECO levels that have been set. ECO levels can be
entered in either lists, which are separated by commas, or ranges, which are
separated by colons.
Both lists and ranges can be specified with the initial command. However,
only one ECO level or one range of ECO levels can be entered in response to
an ECO level prompt (ECO>).

command
qualifiers

None.

DESCRIPTION

Use CHECK ECO to check that one or more ECO levels have been set before
applying a patch. If a specified ECO level has not been previously set in the
image file, PATCH will not apply the current patch. PATCH will not execute
any subsequent commands until it encounters the next SET ECO command.
Remember that an ECO level is not set until the patch that it represents is
applied by the UPDATE command. For example, if you define an ECO level
with the SET ECO command, then immediately check to see whether the
ECO level is set, PATCH returns an error message indicating that the ECO
level is not set.
When you issue the CHECK ECO command, you do not have to list all the
ECO levels that have been set for a particular image file. However, specifying
one or more ECO levels that have not been set will produce an error message.

EXAMPLES
□

PATCH>SET ECO

PATCH>CHECK ECO

3:8,14,16

PATCH>

The CHECK ECO command checks that the patches associated with ECO
levels 3, 4, 5, 6, 7, 8, 14, and 16 have been applied to the image file. The
following PATCH prompt indicates that the specified patches have been
previously set, so PATCH will continue to execute commands. The patch
associated with ECO level 18 will be applied after the UPDATE command is
issued.

PATCH-49

PATCH
CHECK ECO

PATCH>SET ECO 14
PATCH>CHECK ECO 12
7.PATCH-E-EC0N0TSET, eco level 12 not set in DB2: [HARINGTONlBIND_NOW.EXE;4
PATCH>CHECK ECO 12
PATCH>EXAMINE/1NSTRUCTION 800
PATCH>SET ECO 13
PATCH>EXAMINE/INSTRUCTION 800
00000800: TSTL R5

The first CHECK ECO command checks that the patch associated with ECO
level 12 has been applied to the image file. The display indicates that ECO
level 12 has not been set and that the patch it represents has not been applied
to the image file BIND_NOW.EXE. Therefore, the current patch (represented
by ECO level 14) will not be applied. No further commands are executed
until the next SET ECO command.

PATCH-50

PATCH
CHECK NOT ECO

CHECK NOT ECO
Verifies that the specified ECO levels have not been applied and are
available for use.

CHECK NOT ECO eco-level[:eco-level][, ... 7

FORMAT

eco-level

command
parameter

Indicates the ECO levels that are not set. ECO levels can be entered in either
lists, which are separated by commas, or ranges, which are separated by
colons.
Both lists and ranges can be entered with the initial command. However,
only one ECO level or one range of ECO levels can be entered in response to
an ECO level prompt (ECO> ).

command
qualifiers

None.

DESCRIPTION

Use CHECK NOT ECO to check that one or more ECO levels are available
for use in a particular image file.
The CHECK NOT ECO command is the negation of the CHECK ECO
command. It too can be used to confirm whether or not a particular patch has
been applied to an image file. Usually the CHECK NOT ECO command is
used to confirm that the stated ECO levels have not been set and are available
for use in the current image file.
If a specified ECO level is not available for use (that is, it has already been set
in the image), the current patch will not be applied. PATCH will not execute
any subsequent commands until it encounters the next SET ECO command.

EXAMPLES
Q

PATCH^HECK not eco
PATCH>

4:6,10

This command confirms that the ECO levels 4, 5, 6, and 10 are available for
use. The second PATCH prompt indicates that the specified patches have not
been applied, and PATCH will continue to execute commands.
0

patch>check

not eco

EC0>17
eco>exit
%PATCH-E-ECOSET, eco level 17 already set in DB1:[REAVER]MYFILE.EXE;7

In response to the CHECK NOT ECO command, PATCH indicates that ECO
level 17 has already been used in the image file MYFILE.EXE. No further
commands are executed until the next SET ECO command.

PATCH-51

PATCH
CREATE

CREATE
Creates command procedures of PATCH commands. All subse¬
quent successful PATCH commands that modify the image file will
be written to this command procedure.

FORMAT

CREATE [file-spec]

command

file-spec

parameter

Represents the file specification of the command procedure.
You can omit all or some of the fields in the command procedure file specifi¬
cation. PATCH uses the default values listed below for omitted fields.

Field

Default Value

Device and
directory

The current default device and directory for the
process

File name

The name of the input image file

File type

COM

Version

1 greater than the highest command procedure of the
same name

Note that if you store a command procedure in a directory other than the
one that contains the input image file to which the command procedure is
applied, you must set your default to the directory that contains the input
image file before you process the command procedure.

command
qualifiers

None.

DESCRIPTION Use CREATE to create a command procedure that contains all PATCH
commands successfully executed after the CREATE command.
Command procedures facilitate patching several copies of the same image file.
There are two ways to create command procedures. One way is to specify
the CREATE command when you invoke PATCH. All subsequent, successful
commands are applied to the image file and recorded in the command
procedure. A second way is to use a text editor.
When you use CREATE to create a command procedure, PATCH automat¬
ically inserts, as the first entry in the command procedure, the name of the
image file that will incorporate the patches. All symbolic names are converted
to absolute values, and all command names and qualifiers are truncated to
their shorthand notation.
You can issue only one CREATE command per PATCH session. To create
another command procedure, close the input image file and then reopen it.

PATCH-52

PATCH
CREATE

To process the patches contained in the command procedure, issue the
following DCL command:
$ PATCH Qfile-spec

In the above command, the file-spec represents the specification of the
command procedure containing the patches.

EXAMPLE
$ PATCH AVERAGE
PATCH VERSION 4-00 15-Apr-84
PATCH>CREATE

PAT2

PATCH>SET ECO 1
PATCH>SET

MODE NOSYMBOLS

PATCH>EXAMINE 600

00000600:

12345678

PATCH>DELETE 600 = 12345678

old:
00000600:
12345678
new:
00000600:
00000000
PATCH>UPDATE
•/.PATCH-I-WRTFIL, updating image file DBA2: [BRADLEY]AVERAGE.EXE;6
patch>exit
$ SET DEFAULT [NIMROD]
$ SHOW DEFAULT
DBA2:[NIMROD]
$ PATCH <9 [BRADLEY] PAT2

In the above command procedure, PATCH is invoked to patch the image
AVERAGE.EXE in the DBA2:[BRADLEY] directory. The CREATE com¬
mand creates the command procedure PAT2.COM in which all successful
commands are stored.
After the PATCH session ends, the default directory is set to DBA2: [NIMROD]
and the patches in the command procedure PAT2.COM are applied to the
image file [NIMROD] AVERAGE .EXE.

PATCH-53

PATCH
DEFINE

DEFINE
Assigns a specific value to a symbolic name, and then places the
symbolic name in the PATCH symbol table.

FORMAT

command
parameters

DEFINE

symbol-name =value
[,symbol-name =value, ... 7

symbol-name
Specifies a 1- to 31-character user-defined symbol to be associated with the
specified value. The symbol name must start with an alphabetic character,
and can consist of alphanumeric characters, dollar signs ($), underscores (_),
and/or periods (.). (PATCH does not distinguish between uppercase and
lowercase letters; that is, the value ABC is equivalent to the value abc.)
The symbol name cannot be a pathname.

value
Specifies a numeric address or symbolic expression that is to be assigned the
specified symbolic name.

command
qualifiers

None.

DESCRIPTION

Use DEFINE to equate a symbolic name to a specific value and place the
symbolic name in the PATCH symbol table. Once the assignment has been
performed, you can specify the symbolic name in place of the value it denotes
for the duration of the PATCH session. At the end of the PATCH session,
these user-defined symbols are deleted from the PATCH symbol table.
When you use the DEFINE command to create symbolic names, PATCH
always searches the symbol table for these symbolic names first when it
translates a symbol into a value.
More than one symbolic name can be assigned to a single value. Each
symbolic name is recorded in the symbol table and can subsequently be used
to reference the value it denotes.
You can redefine a symbolic name to represent a new value. Then, when you
specify the symbolic name, the most recent value that the symbol denotes is
displayed.
One restriction applies to the use of the DEFINE command. You cannot
specify the /INSTRUCTION or /ASCII mode qualifiers, nor can you set the
INSTRUCTION or ASCII modes, when equating a symbol name to a value.

PATCH-54

PATCH
DEFINE

EXAMPLES
□

PATCH>define SWEDISH = CARW0LV0+144
Symbol " SWEDISH" defined as CARW0LV0+144
patch>EXAMINE SWEDISH

The DEFINE command creates a symbolic name for the value
CAR\VOLVO+144. A subsequent EXAMINE command requests to see the
contents of CAR\VOLVO+144 using the symbol name SWEDISH.
0

patch>define
nam>second_choice
VAL*406
nam>exit
symbol " SECOND.CHOICE"

redefined from 408 to 406

The DEFINE command reassigns the symbol SECOND-CHOICE from the
value 408 to the value 406. The DEFINE command response shows the
reassignment.

PATCH-55

PATCH
DELETE

DELETE
Deletes an instruction or a piece of data.

FORMAT
command
parameters

DELETE location ^current-contents [, ... 7
location
Specifies either a single location whose contents are to be deleted or the
starting address of a sequence of locations whose contents are to be deleted.
The length of the sequence depends on the current mode settings.

current-contents
Specifies one or more data entries or instructions to be deleted. The data or
instructions you specify must be the actual contents.
Do not specify conflicting data types within a single DELETE command.

command
qualifiers

/BYTE
Specifies that data is deleted in byte lengths. The length mode qualifiers
affect only ASCII and numeric data. When you specify an instruction, the
DELETE command ignores the current length setting and deletes the entire
instruction.

/WORD
Specifies that data is deleted in word lengths. The length mode qualifiers
affect only ASCII and numeric data. When you specify an instruction, the
DELETE command ignores the current length setting and deletes the entire
instruction.

/LONG
Specifies that data is deleted in longword lengths. The length mode qualifiers
affect only ASCII and numeric data. When you specify an instruction, the
DELETE command ignores the current length setting and deletes the entire
instruction.
The initial default setting is /LONG.

/OCTAL
Specifies that virtual addresses and numeric data are interpreted and dis¬
played using octal radix. The radix mode qualifiers do not affect symbolic
addresses or ASCII data.

/DECIMAL
Specifies that virtual addresses and numeric data are interpreted and dis¬
played using decimal radix. The radix mode qualifiers do not affect symbolic
addresses or ASCII data.

PATCH-56

PATCH
DELETE

/HEXADECIMAL
Specifies that virtual addresses and numeric data are interpreted and dis¬
played using hexadecimal radix. The radix mode qualifiers do not affect
symbolic addresses or ASCII data.
The initial default setting is /HEXADECIMAL.

/[NOJASCII
Controls whether the data to be deleted is interpreted and displayed as ASCII
data.
When you specify /ASCII, enclose the data within matching quotation marks
(") or apostrophes ('). The current radix setting has no effect on the ASCII
data being deleted; however, the DELETE command truncates the data if it
exceeds the length imposed on it by the current length mode.
The initial default setting is /NOASCII.

/[NOJINSTRUCTION
Controls whether the data to be deleted is interpreted and displayed as VAX
MACRO instructions.
When you specify /INSTRUCTION, enclose the instruction within matching
quotation marks (") or apostrophes ('). The current length setting does not
affect the instruction being deleted.
The initial default setting is /NOINSTRUCTION

[/NOJSYMBOLS
Controls whether locations are displayed as pathnames or symbols, rather
than as numeric addresses.
The initial default setting is /SYMBOLS.

/[NO]GLOBALS
Controls whether the symbolic entry (exactly as entered) is used as the first or
last pathname in a search.
The initial default setting is /NOGLOBALS.

/[NOJSCOPE
Controls whether scope's contribution to a pathname is used to find the
location specified.
The initial default setting is /SCOPE.

DESCRIPTION

Use DELETE to delete an instruction or piece of data from one location or
from several consecutive locations in terms of the current mode settings.
When you use the DELETE command to delete instructions, the instructions
are replaced with NOP instructions. When you use the DELETE command to
delete ASCII and numeric data, the data is replaced with zeros.

PATCH-57

PATCH
DELETE

EXAMPLES

□

PATCH>delete/instruction
00002112: CMPB
NOP
00002112:
NOP
00002113:
00002114:
NOP

2112 = 'CMPB Cr0).(R5)'

The DELETE command replaces the instruction CMPB (R0),(R5) with NOP
instructions.

patch>delete/symbols

loc>7A6
0LD>°e6adde39
old>exit
old: OTSSLINKAGE
new: OTSSLINKAGE

The DELETE command deletes the contents of location 7A6. Because
/SYMBOLS is specified, location 7A6 is reported symbolically.

PATCH-58

PATCH
DEPOSIT

DEPOSIT
Deposits new data or instructions into one or more consecutive
locations.

FORMAT
command
parameters

DEPOSIT

location =new-contents [, ... 7

location
Specifies either a single location whose contents are to be overwritten or
the starting address of a sequence of locations whose contents are to be
overwritten. The length of the sequence depends on the current mode
settings.

new-contents
Specifies one or more data entries or instructions to be inserted. Do not enter
conflicting data types with a single DEPOSIT command.

command
qualifiers

/BYTE
Specifies that data is deposited in byte lengths. The length mode qualifiers
affect only ASCII and numeric data. When you specify an instruction, the
DEPOSIT command ignores the current length setting and deposits the entire
instruction.

/WORD
Specifies that data is deposited in word lengths. The length mode qualifiers
affect only ASCII and numeric data. When you specify an instruction, the
DEPOSIT command ignores the current length setting and deposits the entire
instruction.

/LONG
Specifies that data is deposited in longword lengths. The length mode qual¬
ifiers affect only ASCII and numeric data. When you specify an instruction,
the DEPOSIT command ignores the current length setting and deposits the
entire instruction.
The initial default setting is /LONG.

/OCTAL
Specifies that virtual addresses and numeric data are interpreted and dis¬
played using octal radix. The radix mode qualifiers do not affect symbolic
addresses or ASCII data.

/DECIMAL
Specifies that virtual addresses and numeric data are interpreted and dis¬
played using decimal radix. The radix mode qualifiers do not affect symbolic
addresses or ASCII data.

PATCH-59

PATCH
DEPOSIT

/[NOJASCH
Controls whether the data to be deposited is interpreted and displayed as
ASCII data.
When you specify /ASCII, enclose the data within matching quotation marks
(") or apostrophes ('). The current radix setting has no effect on the ASCII
data being deposited; however, the DEPOSIT command truncates the data if
it exceeds the length imposed on it by the current length mode.
The initial default setting is /NOASCII.

/[NO]INSTRUCTIOI\l
Controls whether the data to be deposited is interpreted and displayed as
VAX MACRO instructions.
When you specify /INSTRUCTION, enclose the instruction within matching
quotation marks (") or apostrophes ('). The current length setting does not
affect the instruction being deleted.
The initial default setting is /NOINSTRUCTION

[/NOJSYMBOLS
Controls whether locations are displayed as pathnames or symbols, rather
than as numeric addresses. The initial default setting is /SYMBOLS.

/[NOJGLOBALS
Controls whether the symbolic entry (exactly as entered) is used as the first or
last pathname in a search. The initial default setting is /NOGLOBALS.

/[NOJSCOPE
Controls whether scope's contribution to a pathname is used to find the
location specified. The initial default setting is /SCOPE.

/PATCH-AREA
Signals PATCH to deposit the data or instructions into the current patch area,
starting at the specified location.

DESCRIPTION

Use DEPOSIT to deposit new data or instructions into one or more consecu¬
tive locations.
When depositing data or instructions, you can replace the contents of a
location or of several consecutive locations in terms of the current mode
settings. The DEPOSIT command does not request verification of the current
contents before replacing the contents with new data or instructions (that is,
this command assumes that you know what you are doing). In cases when
you want to confirm the data or instructions that will be overwritten, use the
REPLACE command.

PATCH-60

PATCH
DEPOSIT

When you are adding instructions to an image file, it is easier to use the
INSERT command. This command performs automatic branching to and
from the patch area.
When you append the /PATCH_AREA qualifier to the DEPOSIT command,
the data or instructions specified are inserted into the current patch area. The
location you supply must be the first free byte in patch area. To determine
the first free byte in patch area, issue the SHOW PATCH—AREA command
or the ALIGN/BYTE command. After you deposit the data, PATCH updates
the patch area string descriptor to reflect the modifications.
Unlike the INSERT and REPLACE commands, the DEPOSIT/PATCH_AREA
command requires that you insert the branch instructions into the appropriate
locations to maintain the logical flow of program execution to and from the
patch area.

EXAMPLES
Q

PATCH>DEPOSIT/ASCII/BYTE 1111 = 'A'
old: 00001111:
'B*
new: 00001111:
'A'

The DEPOSIT command requests that a byte of ASCII data be deposited in
location 1111. The DEPOSIT display indicates that the data was successfully
deposited and that the old contents was B.
E

PATCH>DEP0SIT/INSTRUCTI0N
L0C>413
NEW>'CMPW (Rl),R6'
NEW>EXIT
old: 00000413:
CMPW (R6),R1
new: 00000413:
CMPW (R1),R6

The DEPOSIT command deposits an instruction into location 413. The
/INSTRUCTION qualifier is specified to indicate that an instruction is be¬
ing deposited. The DEPOSIT display indicates that the instruction was
successfully deposited.
E

PATCH>SET PATCH.AREA NEW.PATCH
PATCH>ALIGN/BYTE PAT1
old patch area size:
0000018C
old patch area address:
000004A8
new patch area size:
0000018C
new patch area address:
000004A8
symbol " PATl" defined as:
000004A8
PATCH>DEPOSIT/PATCH_AREA/ASCII
L0OPAT1
NEW> 'RUN'
NEW> 'SKIP'
NEW>EXIT
PATl:
old:
000004AC
old:
PATl:
new:
000004AC
new:

The SET PATCH-AREA command establishes the user-defined patch
area named NEW—PATCH as the current patch area. The ALIGN/BYTE
command realigns the starting address of NEW—PATCH on the first
available byte address and defines the symbol PATl to that address.
The DEPOSIT/PATCH—AREA command is then issued to deposit into
NEW-PATCH at PATl the ASCII data RUN and SKIP.

PATCH-61

PATCH
EVALUATE

EVALUATE
Displays values for arithmetic expressions, values, and
variable-length bit fields.

FORMAT
command
parameter

EVALUATE expression [, ... 7
expression
Indicates an arithmetic expression, a value and corresponding bit field, or a
literal value that is to be evaluated in terms of the current mode settings. As
explained above, when you evaluate a selected bit field in a value, the format
of the expression is
value <high-bit:low-bit>

command
qualifiers

/BYTE
Specifies that data is evaluated in byte lengths. The length mode qualifiers
affect only the evaluation of arithmetic expressions; they have no effect on
the evaluation of bit fields.

/WORD
Specifies that data is evaluated in word lengths. The length mode qualifiers
affect only the evaluation of arithmetic expressions; they have no effect on
the evaluation of bit fields.

/LONG
Specifies that data is evaluated in longword lengths. The length mode
qualifiers affect only the evaluation of arithmetic expressions; they have no
effect on the evaluation of bit fields.
The initial default setting is /LONG.

/OCTAL
Specifies that data is interpreted and displayed using octal radix. The radix
mode qualifiers affect the evaluation of arithmetic expressions and of bit fields
for specific values.

/DECIMAL
Specifies that data is interpreted and displayed using decimal radix. The radix
mode qualifiers affect the evaluation of arithmetic expressions and of bit fields
for specific values.

/HEXADECIMAL
Specifies that data is interpreted and displayed using hexadecimal radix. The
radix mode qualifiers affect the evaluation of arithmetic expressions and of bit
fields for specific values.
The initial default setting is /HEXADECIMAL.

PATCH-62

PATCH
EVALUATE

/[NOJASCII
Controls whether the data is interpreted and displayed as ASCII data. You
cannot set the ASCII mode or use the /ASCII qualifier when you are evaluat¬
ing variable-length bit fields.
The initial default setting is /NOASCII.

/[NOJINSTRUCTION
Controls whether the data is interpreted and displayed as VAX MACRO
instructions. You cannot set the INSTRUCTION mode or use the
/INSTRUCTION qualifier when you are evaluating variable-length bit fields
or ASCII data.
The initial default setting is /NOINSTRUCTION

/[NOJGLOBALS
Controls whether the symbolic entry (exactly as entered) is used as the first or
last pathname in a search.
The initial default setting is /NOGLOBALS.

/[NOJSCOPE
Controls whether scope's contribution to a pathname is used to find the
location specified.
The initial default setting is /SCOPE.

DESCRIPTION

You can use the EVALUATE command to perform binary and unary arith¬
metic operations. The EVALUATE command interprets expressions and
displays results in the current length and radix modes.
You can use the EVALUATE command to determine the value associated
with a symbol or pathname. The values are displayed in terms of the current
length and radix mode setting.
You can use the EVALUATE command to display the current contents of a
specific bit field in a value. The syntax for this command is
PATCH>EVALUATE value <high-bit:low-bit>

The bit position delimiters (high-bit and low-bit) are specified as decimal
integers.
Bit positions range from 0 (least significant bit) to 31 (most significant bit).
PATCH extracts the contents of the bit positions and reports the contents in
longword representation and in terms of the current radix setting. The current
length mode is ignored. Note that ASCII mode and INSTRUCTION mode
cannot be set when you evaluate selected bit positions.

EXAMPLES
Q

PATCH>EVALUATE/DECIMAL 101*123
12423

This command performs the requested arithmetic operation. The values are
interpreted and displayed in decimal representation.

PATCH-63

PATCH
EVALUATE

PATCH>SET MODE DECIMAL
~X200 + <~D65/~012>
518
PATCH>EVALUATE

The EVALUATE command performs the specified arithmetic operation
according to the rules of precedence. PATCH first divides decimal 65 by octal
12, and then adds the quotient to hexadecimal 200. The result is displayed in
decimal representation.
0

PATCH>EVALUATE

~070 <5:3>

00000007

This command calculates the specified bit field value for the octal number 70.
The result is displayed in the current radix setting (in this case, hexadecimal).
Q

PATCH>EVALUATE FDR$PETE
00000800

The EVALUATE command determines that the value assigned to the symbol
FDR$PETE is 800. The result is displayed in the current radix setting (in this
case, decimal).

PATCH-64

PATCH
EXAMINE

EXAMINE
Displays the contents of the specified locations in terms of the
current mode settings.

FORMAT
command
parameter

EXAMINE location[:location][, ... 7
location
Specifies one or more locations whose contents are to be displayed. Several
locations can be specified in a comma-separated list or colon-separated range.
Both lists and ranges can be specified in a single command.
The location parameter can also be represented by the backslash operator (\).
If you do not supply a location, the contents of the next sequential location
will be displayed. The next sequential location depends on the current mode
settings.

command
qualifiers

/BYTE
Specifies that data is displayed in byte lengths. The length mode qualifiers
affect only ASCII and numeric data. When you specify an instruction, the
EXAMINE command ignores the current length setting and displays the entire
instruction.

/WORD
Specifies that data is displayed in word lengths. The length mode qualifiers
affect only ASCII and numeric data. When you specify an instruction, the
EXAMINE command ignores the current length setting and displays the entire
instruction.

/LONG
Specifies that data is displayed in longword lengths. The length mode qual¬
ifiers affect only ASCII and numeric data. When you specify an instruction,
the EXAMINE command ignores the current length setting and displays the
entire instruction.
The initial default setting is /LONG.

/OCTAL
Specifies that virtual addresses and numeric data are interpreted and dis¬
played using octal radix. The radix mode qualifiers do not affect symbolic
addresses or ASCII data.

/DECIMAL
Specifies that virtual addresses and numeric data are interpreted and dis¬
played using decimal radix. The radix mode qualifiers do not affect symbolic
addresses or ASCII data.

PATCH-65

PATCH
EXAMINE

/[NO]ASCII
Controls whether data is displayed as ASCII data.
When you specify /ASCII, the EXAMINE command truncates the data if it
exceeds the limit imposed on it by the current length setting.
The initial default setting is /NOASCII.

/[NOJINSTRUCTION
Controls whether data is displayed as VAX MACRO instructions.
When you specify /INSTRUCTION, the EXAMINE command ignores the
current length setting when displaying an instruction.
The initial default setting is /NOINSTRUCTION

[/NOJSYMBOLS
Controls whether locations are displayed as pathnames or symbols, rather
than as numeric addresses.
The initial default setting is /SYMBOLS.

/[NOJGLOBALS
Controls whether the symbolic entry (exactly as entered) is used as the first or
last pathname in a search.
The initial default setting is /NOGLOBALS.

/[NOJSCOPE
Controls whether scope's contribution to a pathname is used to find the
location specified.
The initial default setting is /SCOPE.

DESCRIPTION

Use EXAMINE to display the contents of the specified locations in terms of
the current mode settings.
You can also use the EXAMINE command to examine the contents of a
branch instruction or the contents of an address displayed in response to the
previous EXAMINE command. To do so, you use the backslash operator (\).

PATCH-66

PATCH
EXAMINE

EXAMPLES
Q

PATCH> EXAMINE/INSTRUCTION/NOSYMBOLS 600
00000600:
BNEQ 634
PATCH> EXAMINE/INSTRUCTION/NOSYMBOLS \
00000634:
TSTL R4

The response to the first EXAMINE command indicates that memory location
600 contains a branch instruction to location 634. Because the backslash
character (\) is specified in the second EXAMINE command, the contents of
location 634 are displayed. The /NOSYMBOLS qualifier requests that the
locations be displayed by virtual addresses.
B

PATCH>EXAMINE/ASCII 650:
00000650:
'FE
'
00000654:
'FI
'
00000658:
'FO
'
0000065C:
'FUM '

The EXAMINE command requests a display in ASCII of all the data between
location 650 and the current location (represented by the dot character).
B

PATCH>set mode SCOPE.SYMBOLS
PATCH>set SCOPE negation

PATCH>SET mode noscope

PATCH>EXAMINE/INSTRUCTION/SCOPE ro.code
NEGATION/RO.CODE:
PUSHL L~NEGATI0N/RW_DATA+14

In the above sequence of commands, the modes SCOPE and SYMBOLS are
set and the scope is established as the module named NEGATION. After
PATCH performs a series of commands, the SCOPE-NOSCOPE mode is
turned off, although the scope is still set to NEGATION.
Still later, the EXAMINE command is specified to request the display of the
instruction in location RO—CODE. The /SCOPE qualifier requests that the
scope be prefixed to RO—CODE and that the symbol table be searched for a
value that matches.
Q

PATCH> EXAMINE/INSTRUCTION
00000600:
BNEQ 634
PATCH> EXAMINE/INSTRUCTION
00000602:
BRW
LPLIST
PATCH> EXAMINE/INSTRUCTION
LPLIST:
MOVL R3.R4

The first EXAMINE command requests that the contents of the current
location (represent by the dot character) be displayed as a VAX MACRO
instruction. The second EXAMINE command requests that the next sequential
location be displayed as a VAX MACRO instruction. The third EXAMINE
command requests that the contents of the destination of the previous branch
instruction (BRW) be displayed.

PATCH-67

PATCH
EXIT

EXIT
Ends a PATCH seion. It also ends a repetitive prompt such as
NEW> , OLD> , or ECO> .

FORMAT

EXIT

command
parameters
command
qualifiers

None.
None.

DESCRIPTION Use EXIT to terminate a repetitive prompt such as NEW>, OLD>, or
ECO>, or to terminate a PATCH session and pass control back to the
command interpreter. (You can also specify CTRL/Z to terminate a PATCH
session. Press CTRL/Z in response to the PATCH prompt (PATCH>).)
Do not type EXIT in response to the value prompt (VAL>) for the DEFINE
command. For this command, only the name prompt (NAM>) recognizes
the EXIT command.

EXAMPLES
Q

PATCH>SET MODE
NEW>INSTRUCTION
NEW>N0SYMB0LS
new>noscope
new>exit
PATCH>

The SET MODE command continuously prompts for new mode settings until
you enter the EXIT command.
g

PATCH>EXIT

$
When you specify the EXIT command in response to a PATCH prompt
(PATCH >), the PATCH session is terminated and control is passed back to
the command interpreter. The DCL prompt, shown here as a dollar sign ($),
indicates that you are no longer in PATCH.
B

PATCH>DEFINE
NAM>TESTl
NEW>500
NAM>TEST2
NEW>800
nam>exit
symbol " TESTl"
symbol " TEST2"
PATCH>

defined as 00000500
defined as 00000800

The DEFINE command assigns the symbols TESTl and TEST2 to 500 and
800, respectively. The EXIT command is entered in response to the name
prompt to terminate this level of prompting.

PATCH-68

PATCH
HELP

HELP
Displays information about any of the other PATCH commands.

topic [subtopic ... 7

FORMAT

HELP

command
parameters

Specifies the name of the command with which you need help.

topic
subtopic
Specifies a particular qualifier or parameter about which you want further
information, or a command keyword that gives you information about a
range of qualifiers or parameters or both.
If you want information about a particular qualifier or parameter, specify it
as a subtopic. Note that when you specify a qualifier, you must include the
preceding slash (/). If you want information about all command qualifiers,
specify "qualifier" as a subtopic. If you want information about all parameters,
specify "parameter" as a subtopic.

command
qualifiers

None.

DESCRIPTION Use HELP to display the following information about any PATCH command:
a description of the command, the format of the command, the qualifiers
that may be specified with the command, and the parameters that may be
specified with the command. In addition, the HELP command provides
information about modes and expressions.

If you want information about a particular qualifier or parameter, specify it
as a subtopic. If you want information about all command qualifiers, specify
"qualifier" as a subtopic. If you want information about all parameters, specify
"parameter" as a subtopic.

EXAMPLE
PATCH>HELP cancel
CANCEL
The CANCEL commands allow the user to reinstate initial
defaults for the various display and addressing characteristics
of PATCH.
Additional information available:
MODE

MODULE

PATCH.AREA

SCOPE

PATCH>

The HELP CANCEL command displays information about the CANCEL
commands.

PATCH-69

PATCH
INSERT

INSERT
Inserts VAX MACRO instructions into specific locations within an
image file.

FORMAT

INSERT location =current-instruction
new-instruction . . .

command
parameters

location
Specifies the address after which one or more new instructions are to be
added.

current-instruction
Specifies the instruction currently occupying the specified location.

new-instruction
Specifies one or more new instructions to be inserted into the image file
following the current instruction.

command
qualifiers

/OCTAL
Specifies that virtual addresses are interpreted and displayed using octal
radix.

/DECIMAL
Specifies that virtual addresses are interpreted and displayed using decimal
radix.

/HEXADECIMAL
Specifies that virtual addresses are interpreted and displayed using hexadeci¬
mal radix.
The initial default setting is /HEXADECIMAL.

/[NO]INSTRUCTION
Controls whether the data to be inserted is interpreted as VAX MACRO
instructions.
To use the INSERT command, you must either specify the /INSTRUCTION
mode qualifier or explicitly set mode to INSTRUCTION.
The initial default setting is /NOINSTRUCTION

[/NOJSYMBOLS
Controls whether locations are displayed as pathnames or symbols, rather
than as numeric addresses.
The initial default setting is /SYMBOLS.

PATCH-70

PATCH
INSERT

/[NOJGLOBALS
Controls whether the symbolic entry (exactly as entered) is used as the first or
last pathname in a search.
The initial default setting is /NOGLOBALS.

/[NOJSCOPE
Controls whether scope's contribution to a pathname is used to find the
location specified.
The initial default setting is /SCOPE.

DESCRIPTION Use INSERT to insert VAX MACRO instructions into specific locations within
an image file. To use this command, you must specify the /INSTRUCTION
qualifier or you must set the INSTRUCTION mode. To insert additional data
into a patch area, use the DEPOSIT/PATCH_AREA command.
Before inserting the new instruction, the INSERT command confirms the con¬
tents of the location preceding the insertion (that is, the current instruction).
New instructions are inserted after the current instruction you specify.
When the INSERT command is executed, it replaces the current instruction
with a branch instruction and places the current instruction and the new
instructions in the current patch area. The last new instruction is always
followed by a branch instruction that redirects the flow of execution back
to the inline code. The INSERT command automatically generates branch
instructions.
After the insertion of new instructions, the patch area string descriptor is
updated to reflect the modifications.
Calculating the Location for the Branch Instruction
When the INSERT command is executed, it replaces the current instruction
with a branch instruction and places the current instruction and the new
instructions in the patch area. If the branch instruction to the patch area is
longer than the current instruction, additional instructions following the cur¬
rent instruction are also moved to the patch area, and the branch instruction
is deposited in the vacated memory locations. Unused memory locations are
filled with NOP instructions.
On the other hand, if the current instruction is longer than the branch
instruction, the unused memory locations are filled with NOP instructions.
Calculating Relative Displacements for Branch Instructions
PATCH calculates the relative displacements for the branch instructions it
generates and recalculates the relative displacements for all branch-type
instructions moved to the patch area. Instructions and data moved to the
patch area may, however, be referenced by instructions not affected by the
move. Note that PATCH does not recalculate any relative displacements in
the unaffected instructions.
Note also that if PATCH moves an instruction with a current address defined
by a symbolic instruction label, you must check and correct any references
made to that label.

PATCH-71

PATCH
INSERT

EXAMPLE
PATCH>SET MODE INSTRUCTION
PATCH>EXAMINE 600
00000600:
MOVL R1,R4
patch>examine
00000602:
BSBB LP.NAME
PATCH>INSERT 602 = 'BSBB LP_NAME'
NEW>'CVTFW R3.R2'
new>exit
LP.NAME
BSBB
00000602
old:
00000604
CMPB
R2.R8
old:
BRW
PAA
00000602
new:
new:
00000605
NOP
new:
00000606
NOP
BSBW
LP.NAME
PAA:
new:
CVTFW
R3.R2
00030374
new:
CMPB
R2.R8
new:
00030377
00000607
BRW
new:
00030740

This example shows the procedure used to insert an additional instruction
into the existing code. After confirming the contents of location 602 and
specifying the new instruction to be inserted, PATCH performs the following
steps.
1

Determines how many instructions from the existing code must be moved
to patch area to make room for a branch instruction.

2 Moves the instructions calculated in step 1 to the current patch area, and
inserts in their places a branch instruction. PATCH calculates the relative
displacement value for the branch instruction and generates a patch area
symbol name to identify the destination of the branch.

3 Fills the unoccupied locations in the existing code with NOP instructions.
4 Recalculates the relative displacements for all branch-type instructions
moved to the patch area.

5 Inserts into the patch area a branch instruction that reroutes the program's
flow of execution back to the inline code.

PATCH-72

PATCH
REPLACE

REPLACE
Replaces the contents of one or more locations with new instruc¬
tions or data in terms of the current mode settings.

FORMAT

command
parameters

REPLACE

location =current-contents [,-■■]
new-content . . .

location
Specifies either a single location whose contents are to be replaced or the
starting address of a sequence of locations whose contents are to be replaced.
The length of the sequence depends on the current mode settings.

current-contents
Specifies one or more data entries or instructions to be replaced. The data or
instructions you specify must be the actual contents.
Do not specify conflicting data types within a single REPLACE command.

new-contents
Specifies one or more data entries or instructions that are to replace the
current contents.
Do not specify conflicting data types within a single REPLACE command.

command
qualifiers

/BYTE
Specifies that data is replaced in byte lengths. The length mode qualifiers
affect only ASCII and numeric data. When you specify an instruction, the
REPLACE command ignores the current length setting and replaces the entire
instruction.

/WORD
Specifies that data is replaced in word lengths. The length mode qualifiers
affect only ASCII and numeric data. When you specify an instruction, the
REPLACE command ignores the current length setting and replaces the entire
instruction.

/LONG
Specifies that data is replaced in longword lengths. The length mode quali¬
fiers affect only ASCII and numeric data. When you specify an instruction,
the REPLACE command ignores the current length setting and replaces the
entire instruction.
The initial default setting is /LONG.

/OCTAL
Specifies that virtual addresses and numeric data are interpreted and dis¬
played using octal radix. The radix mode qualifiers do not affect symbolic
addresses or ASCII data.

PATCH-73

PATCH
REPLACE

/DECIMAL
Specifies that virtual addresses and numeric data are interpreted and dis¬
played using decimal radix. The radix mode qualifiers do not affect symbolic
addresses or ASCII data.

/[NOJASCII
Controls whether the data to be replaced and the data to be deposited are
interpreted and displayed as ASCII data.
When you specify /ASCII, enclose the data within matching quotation marks
(") or apostrophes ('). The current radix setting has no effect on ASCII
data being replaced or deposited; however, the REPLACE command truncates
ASCII data if it exceeds the length imposed on it by the current length setting.
The initial default setting is /NOASCII.

/[NOJINSTRUCTION
Controls whether the data to be replaced and the data to be deposited are
interpreted and displayed as VAX MACRO instructions.
When you specify /INSTRUCTION, enclose the instructions within matching
quotation marks (") or apostrophes ('). The current length setting does not
affect the instruction being replaced.
The initial default setting is /NOINSTRUCTION.

[/NO]SYMBOLS
Controls whether locations are displayed as pathnames or symbols, rather
than as numeric addresses.
The initial default setting is /SYMBOLS.

/[NOJGLOBALS
Controls whether the symbolic entry (exactly as entered) is used as the first or
last pathname in a search.
The initial default setting is /NOGLOBALS.

/[NOJSCOPE
Controls whether scope's contribution to a pathname is used to find the
location specified.
The initial default setting is /SCOPE.

PATCH-74

PATCH
REPLACE

DESCRIPTION Use REPLACE to replace the contents of one or more locations with new
instructions or data in terms of the current mode settings. Before performing
the replacement, the REPLACE command confirms the contents of the
specified locations.
When you replace instructions and the new instructions occupy more bytes
in memory than the current instructions, the new instructions are moved to
the patch area and PATCH generates branch instructions to maintain the
program's logical flow of execution. PATCH generates branch instructions for
the REPLACE command the same way that it does for the INSERT command.
(See the INSERT command description for a description of the mechanics
of generating branch instructions.) All unused bytes are filled with NOP
instructions.
If patch area is used to accommodate the new contents, the patch area string
descriptor is updated to reflect the modifications.
When you replace ASCII or numeric data, the number of replacement entries
cannot exceed the number of existing entries. This means, for example, that
if you confirm the contents of six consecutive locations, you can replace the
contents of only those six locations. If the number of replacement entries is
less than the number of existing entries, the remaining locations are filled
with zeros.
In addition, PATCH truncates replacement entries if they exceed the limit
imposed on them by the current length mode. For ASCII characters, the
right-most characters are discarded. For numeric data, the left-most digits are
discarded.
PATCH calculates the relative displacements for the branch instructions it
generates and recalculates the relative displacements for all branch-type
instructions moved to the patch area. Instructions and data moved to the
patch area may be referenced by instructions not affected by the move. Note
that PATCH does not recalculate the relative displacement values in the
unaffected instructions.
Note also that if PATCH moves an instruction with a current address defined
as a symbolic label, you must check and correct any references made to that
label.

EXAMPLES
Q

PATCH>SET MODE INSTRUCTION, NOSYMBOLS
PATCH>REPLACE 600 = 1TSTL R4'
NEW>'CMPB R2.R4'
NEW>EXIT
00000600: TSTL R4
old:
00000602: BEQL 00000610
old:
new:
00000600: BRW 0000784A
00000604: NOP
new:
0000784A: CMPB R2.R4
new:
0000784D: BNEQ 00007852
new:
0000784F: BRW 00000610
new:
00007852: BRW 00000605
new:

The instruction occupying location 600 is replaced with the instruction CMPB
R2,R4. This instruction occupies more bytes than the instruction TSTL R4.
Thus, to make room for CMPB R2,R4, the instructions CMPB R2,R4 and
the instruction that follows TSTL R4 are moved to the current patch area.
A branch instruction is deposited in place of TSTL R4 to direct program

PATCH—75

PATCH
REPLACE

execution to the patch area. The last instruction deposited in the patch area is
a branch instruction back to the inline code.
g

PATCH>SET SCOPE MODI
PATCH>REPLACE/SCOPE R0_C0DE+20 = 1000
NEW>100
NEW>EXIT
old:
M0D1\E:
00001000
new:
M0D1\E:
00000100

The SET SCOPE command establishes the current symbolic scope as MODI.
A subsequent REPLACE command requests that the contents of location
RO_CODE+20 in the module named MODI be replaced with new data. The
display indicates that the replacement was successful. Note that the location
is reported by the pathname MODl\E because the symbol E is the closest
symbol to location RO_CODE+20.

PATCH-76

PATCH
SET ECO

SET ECO
Assigns an ECO level to the patch that you are creating.

FORMAT
command
parameter
command
qualifiers

SET ECO eco-level
eco-level
Specifies a decimal integer between 1 and 128, inclusive. ECO levels outside
this range of integers are illegal.

None.

DESCRIPTION Use SET ECO to define the ECO level for the patch that you are developing.
Whenever you apply a patch to an image file, the first command you type
should be a SET ECO command. This command provides you with a way
to identify your patches easily. More important, however, it lets you process
selected patches using a command procedure. When PATCH processes
a command procedure, it searches the file for ECO levels and processes
only those patches represented by the specified ECO levels. Patches not
represented by ECO levels are not processed.
You can issue as many SET ECO commands as necessary during a PATCH
session; however, once you specify an ECO level, that level can never be
used again for that particular image file. Furthermore, whenever you begin
a patch with a SET ECO command, you must also terminate the patch with
the UPDATE command. If you fail to issue the UPDATE command (1) the
ECO level specified with the SET ECO command is not set (hence, the patch
is not applied to the image file), and (2) you cannot issue another SET ECO
command.

EXAMPLE
PATCH>SET ECO 15

PATCH>UPDATE
7.PATCH-I-WRTFIL, updating image file DBA3: [HOWARD]NEWFILE.EXE;2
PATCH>CHECK NOT ECO 15
•/.PATCH-E-ECOSET, eco level 15 already set in DBA3: [HOWARD]NEWFILE.EXE;2

The SET ECO command defines the ECO level for the subsequent patch as
15. The commands are then entered. When the UPDATE command is issued,
the ECO level is set and the image file is updated to include the effects of the
new commands. The CHECK NOT ECO indicates that ECO level 15 is set in
the image file NEWFILE.EXE.

PATCH—77

PATCH
SET MODE

SET MODE
Controls the syntax of the other PATCH commands that you enter,
as well as the values that PATCH displays.

FORMAT
command
parameter

SET MODE mode [, . . . 7
mode
Specifies one or more modes from the context, radix, length, and symbol
search mode categories to be established as the current modes. These modes
determine how PATCH interprets entries and displays output.
The commands that are affected by the entry and display modes are DELETE,
DEPOSIT, EVALUATE, EXAMINE, INSERT, REPLACE, and VERIFY. Note
that you can set the modes by using mode qualifiers with these commands.

PATCH-78

Mode

Description

BYTE

Specifies that data is interpreted in byte lengths. The
length mode qualifiers affect only ASCII and numeric data.

WORD

Specifies that data is interpreted in word lengths. The
length mode qualifiers affect only ASCII and numeric data.

LONG

Specifies that data is interpreted in longword lengths. The
length mode qualifiers affect only ASCII and numeric data.
The initial default setting is /LONG.

OCTAL

Specifies that virtual addresses and numeric data are
interpreted and displayed using octal radix. The radix mode
qualifiers do not affect symbolic addresses or ASCII data.

DECIMAL

Specifies that virtual addresses and numeric data are
interpreted and displayed using decimal radix. The radix
mode qualifiers do not affect symbolic addresses or ASCII
data.

HEXADECIMAL

Specifies that virtual addresses and numeric data are
interpreted and displayed using hexadecimal radix. The
radix mode qualifiers do not affect symbolic addresses or
ASCII data. The initial default setting is HEXADECIMAL.

[NO]ASCII

Control whether data is to be interpreted and displayed
as ASCII data. When you specify ASCII, enclose the data
within matching quotation marks (") or apostrophes (').
The initial default setting is NO ASCII.

[NO]INSTRUCTION

Controls whether the data is interpreted and displayed as
VAX MACRO instructions. When you specify INSTRUC¬
TION, enclose the instruction within matching quotation
marks (") or apostrophes ('). The initial default setting is
NOINSTRUCTION.

[NO]SYMBOLS

Controls whether locations are displayed as pathnames
or symbols, rather than as numeric addresses. The initial
default setting is SYMBOLS.

PATCH
SET MODE

command
qualifiers

Mode

Description

[NOJGLOBALS

Controls whether the symbolic entry (exactly as entered) is
used as the first or last pathname in a search. The initial
default setting is NOGLOBALS.

[NOJSCOPE

Controls whether scope's contribution to a pathname
is used to find the location specified. The initial default
setting is SCOPE.

None.

DESCRIPTION Use SET MODE to control the syntax of the commands you enter and the
values PATCH displays.

EXAMPLES
Q

PATCH>SET MODE INSTRUCTION.GLOBALS,NOSYMBOLS

This command requests that the modes INSTRUCTION, GLOBALS, and
NOSYMBOLS be established as the current modes.
Q

PATCH>SET MODE INSTRUCTION
PATCH>DEPOSIT 78B = 'BEQL NEWPATCH'

This SET MODE command establishes INSTRUCTION mode as a cur¬
rent mode setting. A subsequent DEPOSIT command can then deposit an
instruction without specifying the /INSTRUCTION mode qualifier.
0

PATCH>SET MODE
NEW>OCTAL
NEW>WORD
NEW>EXIT

In this example, the SET MODE continuously prompts for new modes until
EXIT is typed.

PATCH—79

PATCH
SET MODULE

SET MODULE
Enters local symbol information from the specified modules into
PATCH’S symbol table.

FORMAT
command
parameter

SET MODULE module-name [, ... 7
module-name
Specifies the name of one or more modules whose local symbols are to be
entered in the symbol table.
Do not specify a module name if you include the /ALL qualifier.

command
qualifier

/ALL

DESCRIPTION

Use SET MODULE to enter local symbol information from the specified
modules into PATCH'S symbol table, provided you followed the rules for
passing local symbol information to PATCH.

Requests that local symbol information from all the modules in the image file
be entered in the symbol table.

If the symbol table is too small to accommodate the local symbol information,
PATCH displays an error message.
Note that if you are patching a shareable image, no local or global symbol
information is passed to PATCH; only universal symbols can be accessed.

EXAMPLES
Q

PATCH>SET MODULE
GREAT_APES
PATCH>EXAMINE/ASCII ORANGUTANS:ORANGUTANS+7
GREAT_APES\ORANGUTANS:
'AMAZ'
GREAT_APES\0RANGUTANS+4:
'ING '

The SET MODULE command enters all local symbol information in the
module GREAT_APES into the symbol table. A subsequent EXAMINE
command can use the local symbol ORANGUTANS to reference particular
locations.
S

PATCH>SET MODULE/ALL

This command requests that all symbol information from all modules be
added to the symbol table.

PATCH-80

PATCH
SET PATCH-AREA

SET PATCH-AREA
Overrides the use of the default patch area in favor of the patch area
that you defined at assembly or compile time.

FORMAT
command
parameter

SET PATCH-AREA address-of-descriptor
address-of-descriptor
Defines the address of the patch area descriptor. The address of the patch
area descriptor can be represented as a symbol or a numeric constant.
If you issue the SET PATCH—AREA command without the /INITIALIZE
qualifier, the address-of-descriptor is the address of the patch area descriptor
defined in the source program.
If you use the /INITIALIZE qualifier, the address-of-descriptor is the address
where PATCH will locate the patch area descriptor. When you use the
/INITIALIZE qualifier, PATCH creates the descriptor and locates it in the first
eight bytes of the user-defined patch area.

command
qualifier

/INITIALIZE=size - expression
Creates a patch area descriptor and locates it in the first eight bytes of the
patch area. /INITIALIZE must precede the address-of-descriptor.
The size-expression defines the size, in bytes, of the patch area. In order to
accommodate the descriptor and PATCH entries, the size-expression must be
eight bytes larger than the area needed for patches.
If the value of the size-expression is specified as zero (0) or is greater than
the number of bytes contained in the patch area, PATCH will use a default
size value. The default size is the number of unused bytes in the patch area
image section, excluding eight bytes for the descriptor. PATCH issues an
informational message when it uses the default size. The default size must be
at least 12 bytes.

DESCRIPTION Use SET PATCH-AREA to override the use of the default patch area in favor
of the patch area you defined at assembly or compile time. A user-defined
patch area, like the default patch area, must have a patch area descriptor.

There are two ways to set up a user-defined patch area in the source program.
First, you can initialize the patch area at assembly time. When you access this
type of user-defined patch area, do not use the /INITIALIZE qualifier.
Alternatively, you can initialize the patch area at patch time. When you
access the user-defined patch area, use the /INITIALIZE qualifier. PATCH
will create the descriptor and locate it in the first eight bytes of the patch area.
If you plan to use the SET PATCH-AREA command without the
/INITIALIZE qualifier, you must define the contents and location of the
patch area descriptor within the source program. When you assemble and
link your program, the patch area code will not be shareable and will incur
additional overhead during image activation.

PATCH-81

PATCH
SET PATCH-AREA

If you plan to use the SET PATCH-AREA command with the /INITIALIZE
qualifier, you need not define the patch area descriptor in your program.
You should, however, declare the size and starting address of the patch area
as global symbols. When you issue the SET PATCH—ARE A/INITIALIZE
command during a patch session, PATCH will create the patch area descriptor
and place it in the first eight bytes of the patch area. By letting PATCH build
the descriptor, you can avoid extra overhead during image activation, and
retain the shareable characteristics of the image.
The following sections show the two ways to set aside a patch area in a VAX
MACRO program.

The SET PATCH-AREA Command Without /INITIALIZE
The SET PATCH—AREA command establishes a user-defined patch area
as the current patch area. To create a user-defined patch area that will be
accessed with the SET PATCH—AREA command, follow these steps:
1

Declare a size for the patch area.

2 Create a patch area descriptor that specifies the size and address of the
first free byte of the patch area. Define a global symbol to represent the
start of the descriptor.

3 Declare storage for the patch area.
In PATCH, issue the SET PATCH_AREA command using the following
format:
SET PATCH_AREA address-of-descriptor

The address-of-descriptor is the address of the patch area descriptor.
This example shows a source program with global symbols for the size of
the patch area, the starting address of the patch area, and the patch area
descriptor.
.ENTRY

BEGIN.M<>
;U8er-written code
;End of useful code

;Declare Patch Area and its associated descriptor
PATCH.SIZE ==
PATCH.DESC::
PATCH_AREA::

512
.LONG
PATCH.SIZE
.ADDRESS PATCH.AREA
.BLKB
PATCH.SIZE
.END BEGIN
;End of program

After invoking PATCH, you can access the patch area by issuing the SET
PATCH—AREA command followed by the address of the patch area de¬
scriptor. In this example, you would access user-defined patch area like
this:
PATCH> SET PATCH.AREA PATCH.DESC

In order to use the global symbol PATCH—DESC, make sure you follow the
rules for passing symbols to PATCH and placing symbols in PATCH'S symbol
table.

PATCH-82

PATCH
SET PATCH-AREA

The SET PATCH-AREA Command With /INITIALIZE
When you use the /INITIALIZE qualifier PATCH creates a patch area
descriptor and also establishes the user-defined patch area as the cur¬
rent patch area. To create patch area that will be accessed with SET
PATCH-ARE A/INITIALIZE, follow these steps:
1

Declare a size for the patch area. The size must include eight bytes for the
patch area descriptor.

2 Define a global symbol to represent the starting address of the patch area.
PATCH will place the patch area descriptor in the first eight bytes of the
patch area.
In PATCH, issue the SET PATCH-AREA command with the /INITIALIZE
qualifier, as shown below:
SET PATCH_AREA/INITIALIZE=8ize-expres8ion address-of-descriptor

The size-expression indicates the size, in bytes, of the patch area. This should
include eight bytes for the descriptor. The address-of-descriptor is the address
where PATCH will locate the patch area descriptor. As explained earlier,
PATCH builds the descriptor and places it in the first eight bytes of the
user-defined patch area.
Both the size-expression and the address-of-descriptor may be expressed
as numeric constants, as global symbols defined within the image, or as
expressions using combinations of numeric constants and symbols. The
/INITIALIZE qualifier must precede the address-of-descriptor argument.
This example shows a source program with global symbols for the size and
starting address of a user-defined patch area:
.ENTRY BEGIN,M<>
;User-written code
End of useful code
;Declare Patch Area
descriptor
PATCH.SIZE ==
PATCH.AREA::

Add eight bytes for the

512+8
.BLKB PATCH.SIZE
.END GIN
;End of program

After invoking PATCH, access the user-defined patch area as follows:
PATCH>SET PATCH_AREA/INITIALIZE=PATCH_SIZE PATCH.AREA

This command initializes the patch area descriptor and locates it in the first
eight bytes of PATCH—AREA. The first longword of the descriptor contains
the size of the patch area available for patches (512 bytes). The second
longword contains the location of the first free byte of the patch area. In this
example, the first free byte is the byte immediately following the descriptor.
If you specify an invalid size expression, PATCH will compute and use a
default size for the patch area. To use the /INITIALIZE qualifier, the default
size must be at least 12 bytes. If the default size is less than 12, PATCH
issues the following error message and does not initialize the descriptor:
%PATCH-E-NOPATAREA, Insufficient patch area of xxxxxxxx size=dddddddd

PATCH-83

PATCH
SET PATCH-AREA

PATCH computes the default size of the patch area in the following order:
1

Computing the number of bytes in the image section containing the patch
area. This is computed by multiplying the number of pages in the image
section by 512.

2 Subtracting eight bytes for the patch area descriptor.
3 Subtracting the number of bytes in the image section that have already
been used by the program code that precedes the patch area. The number
of used bytes is computed by multiplying the section base page number
by 512 to find the virtual address of the start of the image section. This
value is then subtracted from the virtual address of the start of the patch
area.
This is shown in the following formula:
Size = [(#page8_in_8ection_containing_patch_area * 512) - 8][patch_area_address - (section_base_page_number * 512)]

If you do not know the correct patch area size, use the value zero (0) as the
size argument. PATCH will substitute the default size when it builds the
descriptor, as long as the default size is at least 12. PATCH will issue the
following informational message:
'/.PATCH-I-BADINITSZ, illegal size value, defaulting patch size to XXXXXXXX bytes

If you issue the SET PATCH-AREA command with the /INITIALIZE quali¬
fier and the descriptor has already been built, PATCH displays the following
message:
'/.PATCH-1-PREVINIT, patch area has previously been initialized

PATCH does, however, establish the specified user-defined patch area as the
current patch area. PATCH assumes that if the contents of the descriptor are
nonzero, the descriptor was previously built.

EXAMPLES
Q

PATCH>SET PATCH.AREA LRDPATCHES
PATCH>SHOW PATCH.AREA
current patch area size:
0000004F
current patch area address:
000005F2

The SET PATCH—AREA command establishes the user-defined patch area as
the current patch area. The patch area descriptor is located at LRDPATCHES.
The SHOW PATCH—AREA command reports the current status of LRD¬
PATCHES. With this information, you can deposit instructions or data into
the user-defined patch area.
B

PATCH>SET PATCH_AREA/INIT=PATSIZ UPATCH.AREA
PATCH>SHOW PATCH.AREA
current patch area size:
00000200
current patch area address:
00000408

The SET PATCH_AREA/INITIALIZE command establishes the user-defined
patch area UPATCH—AREA as the current patch area. The size of this area
is PATSIZ. The command also initializes a patch area descriptor, which is
stored in the first eight bytes of UPATCH—AREA. The symbols PATSIZ
and UPATCH_AREA were defined in the source program. The SHOW
PATCH_AREA command displays the current patch area size, and the
address of the first free byte of UPATCH—AREA.

PATCH-84

PATCH
SET SCOPE

SET SCOPE
Establishes the specified module name as the explicit scope to be
used for translating pathnames and symbols into values.

FORMAT

SET SCOPE module-name [\routine-name [\ ... 77

command
parameter

Specifies the name of the module to which the scope is to be set.

module-name
routine-name
Specifies the name of a routine contained in the module to which the scope is
to be set.

command
qualifiers

None.

DESCRIPTION Use SET SCOPE to establish the specified module name (and routine name,
if specified) as the explicit scope to be used under the rules for translating
pathnames and symbols into values.
PATCH also inserts local symbol information associated with the specified
module into the symbol table when you type the SET SCOPE. If the symbol
table is too small to accommodate this information, PATCH issues an error
message.
Use the SHOW MODULE command to determine the modules to which the
scope can be set.
If the local symbols in a specific module have not been entered in the symbol
table by the SET MODULE command, the SET SCOPE command forces those
symbols into the table.

EXAMPLES
Q

PATCH>SET SCOPE CARP.LPT

This set command establishes the scope as CARP_LPT.
0

PATCH>SET SCOPE
NEW>LIP_SIGN
•/.PATCH-W-NOSUCHMODU, no such module name " LIP.SIGN"

In this example, there is no such module named LIP_SIGN. Therefore, the
SET SCOPE command fails and the previous scope setting is retained.

PATCH-85

PATCH
SHOW MODE

SHOW MODE
Displays the modes that are currently set.

FORMAT

SHOW MODE

command
parameters
command
qualifiers

None.

DESCRIPTION

Use SHOW MODE to report the modes that are currently set. This command
is used primarily with the SET MODE and/or CANCEL MODE commands.
It indicates the condition of the current modes, enabling you to change one or
more of them if necessary.

None.

When you issue the SHOW MODE command, the mode values are always
displayed in lowercase letters.

EXAMPLE
PATCH> SHOW MODE
modes: symbols, noinstruction, noascii, scope, noglobals, hexadecimal long

The SHOW MODE command requests that the current modes be displayed.

PATCH-86

PATCH
SHOW MODULE

SHOW MODULE
Displays all of the modules in the image file and indicates whether
the symbols contained in the modules area are available for use.

FORMAT

SHOW MODULE

command
parameters
command
qualifiers

None.
None.

DESCRIPTION Use SHOW MODULE to request PATCH to display all the modules in the

image file and indicate whether the symbols contained in the modules are
available for use. It also indicates the amount of symbol table space required
by each module and routine and the total amount of unused space remaining
in the symbol table.
The SHOW MODULE command reports an informational error message if no
local symbol information was passed to PATCH.

EXAMPLE
PATCH>SHOW MODULE
module name
symbols
AVERAGE
OTSSLINKAGE

no
no

total modules:
remaining size:

2.
64052.

size
52.
128.

PATCH>SET MODULE/ALL
PATCH> SHOW MODULE
module name
symbols

size

AVERAGE
OTSSLINKAGE

yes
yes

52.
128.

total modules:
remaining size:

2.
63880.

The first SHOW MODULE command indicates that there are two modules in
the current image file, though neither one has its local symbols entered into
the symbol table. The SET MODULE command requests that all local symbol
information be entered into the symbol table. The second SHOW MODULE
command confirms the presence of the local symbols in the symbol table.

PATCH-87

PATCH
SHOW PATCH-AREA

SHOW PATCH—AREA
Reports the size and starting address (in hexadecimal) of the current
patch area.

FORMAT

SHOW PATCH-AREA

command
parameters
command
qualifiers

None.

DESCRIPTION

Use SHOW PATCH-AREA to report the size and starting address of the
current patch area in hexadecimal representation, regardless of the current
radix setting. Generally, you use this command with either the ALIGN
command or the DEPOSIT/PATCH—AREA command. In both cases, you
want to know the status of the patch area before realigning it or depositing
data in it.

None.

EXAMPLE
PATCH>SH0W PATCH.AREA
00000030
current patch area size:
current patch area address:
00000308
PATCH>DEPOSIT/PATCH_AREA/ASCII
308= 'AT
old:
00000308:
new:
00000308: 'AT'

The SHOW PATCH—AREA display reports that the current patch area size
is 30 bytes and the starting address is memory location 308. A subsequent
DEPOSIT command can deposit data into the patch area.

PATCH-88

PATCH
SHOW SCOPE

SHOW SCOPE
Displays the current scope setting.

FORMAT

SHOW SCOPE

command
parameters
command
qualifiers

None.

DESCRIPTION

Use SHOW SCOPE to display the current scope setting.

None.

EXAMPLE
PATCH>SHOW SCOPE
scope:
TEMPI
PATCH>EXAMINE DEGREES-*-8

The SHOW SCOPE command indicates that the current scope setting is
TEMPI. A subsequent EXAMINE command can reference a location using
local symbol information contained in TEMPI.

PATCH-89

PATCH
UPDATE

UPDATE
Applies a patch to an image file.

FORMAT

UPDATE

command
parameters
command
qualifiers

None.

DESCRIPTION

Use UPDATE to apply a patch to the image file. The UPDATE command is
a patch terminator. This command applies the previous patch to the image
file and thus creates an output image file. If you fail to issue the UPDATE
command, no output image file is created.

None.

During a single execution of PATCH, you can specify the UPDATE command
more than once. The first UPDATE command specified creates a new output
image file. Subsequent UPDATE commands (specified during that PATCH
session) overwrite the output image file. That is, a new version of the output
image file is not created.
If a SET ECO command is issued, a subsequent UPDATE command auto¬
matically sets the ECO level specified. (See the description of the SET ECO
command.)

EXAMPLE
PATCH>UPDATE
•/.PATCH-I-WRTFIL, updating image file DB1: [MASON]HOROSCOPE.EXE;4

The UPDATE command applies the previous patch to the image file
HOROSCOPE.EXE. The UPDATE display indicates that the image file has
been successfully updated.

PATCH-90

PATCH
VERIFY

VERIFY
Confirms that a location (or several consecutive locations) contains
the specified contents-either data or instructions.

FORMAT
command
parameters

VERIFY location =current-contents[, . . . ]

location
Specifies either a single location whose contents are to be checked or the
starting address of a sequence of locations whose contents are to be checked.
The length of the sequence depends on the current mode settings.

current-contents
Specifies one or more data entries or instructions to be verified. The data or
instructions you verify must be the actual contents.
Do not specify conflicting data types within a single VERIFY command.

command
qualifiers

/BYTE
Specifies that data is verified in byte lengths. The length mode qualifiers
affect only ASCII and numeric data. When you specify an instruction, the
VERIFY command ignores the current length setting and verifies the entire
instruction.

/WORD
Specifies that data is verified in word lengths. The length mode qualifiers
affect only ASCII and numeric data. When you specify an instruction, the
VERIFY command ignores the current length setting and verifies the entire
instruction.

/LONG
Specifies that data is verified in longword lengths. The length mode qualifiers
affect only ASCII and numeric data. When you specify an instruction, the
VERIFY command ignores the current length setting and verifies the entire
instruction.
The initial default setting is /LONG.

/OCTAL
Specifies that virtual addresses and numeric data are interpreted and dis¬
played using octal radix. The radix mode qualifiers do not affect symbolic
addresses or ASCII data.

/DECIMAL
Specifies that virtual addresses and numeric data are interpreted and dis¬
played using decimal radix. The radix mode qualifiers do not affect symbolic
addresses or ASCII data.

/HEXADECIMAL
Specifies that virtual addresses and numeric data are interpreted and dis¬
played using hexadecimal radix. The radix mode qualifiers do not affect
symbolic addresses or ASCII data.

PATCH-91

PATCH
VERIFY

The initial default setting is /HEXADECIMAL.

/[NOJASCH
Controls whether the data to be verified is interpreted and displayed as ASCII
data.
When you specify /ASCII, enclose the data within matching quotation marks
(") or apostrophes (7). The current radix setting has no effect on the ASCII
data being verified; however, the VERIFY command truncates the data if it
exceeds the length imposed on it by the current length mode.
The initial default setting is /NOASCII.

/[NO]INSTRUCTION
Controls whether the data to be verified is interpreted and displayed as VAX
MACRO instructions.
When you specify /INSTRUCTION, enclose the instruction within matching
quotation marks (77) or apostrophes (7). The current length setting does not
affect the instruction being verified.
The initial default setting is /NOINSTRUCTION

[/NOJSYMBOLS
Controls whether locations are displayed as pathnames or symbols, rather
than as numeric addresses.
The initial default setting is /SYMBOLS.

/[NO]GLOBALS
Controls whether the symbolic entry (exactly as entered) is used as the first or
last pathname in a search.
The initial default setting is /NOGLOBALS.

/[NOJSCOPE
Controls whether scope's contribution to a pathname is used to find the
location specified.
The initial default setting is /SCOPE.

DESCRIPTION

Use VERIFY to confirm that a location or several consecutive locations contain
the specified contents (instructions or data).
Generally, you should use the VERIFY command with the DEPOSIT com¬
mand. The DEPOSIT command does not confirm the entries before overwrit¬
ing them. Therefore, to make certain you know the contents of the locations
that will be modified, issue the VERIFY command first.
The VERIFY command is also useful when you are patching an image file
by means of a command procedure. Using the VERIFY command, you can
check particular locations before attempting to modify them. If the VERIFY
command fails, that patch is not applied, and PATCH skips to the next
SET ECO command. If no other SET ECO command exists, the command
procedure is terminated.

PATCH-92

PATCH
VERIFY

EXAMPLE
PATCH>VERIFY/ASCII/NOSYMBOLS 6FF='RAIN1
old:
000006FF:
'RAIN'

The VERIFY command confirms that the ASCII text RAIN resides in loca¬
tion 6FF. The /NOSYMBOLS mode qualifier requests that location 6FF be
displayed as a virtual address in terms of the current radix.

PATCH-93

This example illustrates an interactive PATCH session. The follow
MACRO program prompts for a decimal integer, and then display
negation of the integer. The source program contains an error, so t
does not run properly. You will see how to patch the image file to
error.
0000
0000
0000
0000
0000

1
2
3
4
5 PROMPT:

.TITLE NEGATION - Calculates negation of decimal integer
.IDENT /01/
.SUBTITLE - Pure Data
.PSECT RO.DATA.NOWRT.NOEXE.LONG
.ASCII /Enter decimal integer: /

oooc
0017
0017
0017
0025
0031
0033
0000
0000
0000
0000
0008
0008
008C
008C
0090
0090
0094
0094
0094
0094
0094
00E4
00E4
00E4
00E4
00E4
00E4
0128
0128
0000
0000
0000
0002
000F
001C
0029
002F
0035
0035
003C
0043
004E
004E
004E
004E
004E
004E
006D

-PROMPT
6 PROMPT.LEN =
7 RESULT.FAO:
.ASCID /The negation is !SL./
8

9
.SUBTITLE - Impure Data
.PSECT RW.DATA,NOEXE,LONG
10
=
132
;Buffer size
11 BUFFER.SIZE
12 BUFFER.DESC:
BUFFER.SIZE.BUFFER
13
.LONG
descriptor for buffer
14 BUFFER:
BUFFER.SIZE
. BLKB
15
;Buffer to get line
16 INTEGER:
17
.BLKL
1
;Input integer
18 RESULT:
.BLKL
19
1
;Result of operation
20
21
.SUBTITLE - Define RAB and FAB for terminal I/O
22 TRMFAB: $FAB
FNM=TT:,;FAB for terminal
23
FAC=<PUT,GET>,- ;Use for input and output
24
RAT=CR
25
FAB=TRMFAB,;RAB for terminal
26 TRMRAB: $RAB
27
UBF=BUFFER,28
USZ=BUFFER_SIZE,29
R0P=PMT30
PBF=PROMPT,PSZ=PROMPT_LEN
31
32
.SUBTITLE - Program Entry Point
33
.PSECT R0_C0DE.EXE,NOWRT
34
.ENTRY ENTRY.POINT, ~M<>
35
$0PEN
FAB=TRMFAB
36
;0pen terminal file
37
$C0NNECT
RAB=TRMRAB
;Connect record stream
RAB=TRMRAB
38
$GET
;Get input from terminal
39
PUSHAL INTEGER
;Pu8h integer address on
RAB$L_RBF+TRMRAB
40
PUSHL
;Pu8h starting address of
41
;input on stack
42
MOVZWL RAB$W_RSZ+TRMRAB,-(SP)
ipush length of input on stack
43
CALLS
#3,G~LIB$CVT_DTB
;Convert to binary
44
MOVL
INTEGER,RESULT
Calculate negation
45
46 ;determine length and contents of result
47
$FA0_S CTRSTR=RESULT_FAO.;Use system service to
OUTLEN=TRMRAB+RAB$W_RSZ,
48
;convert binary result
49
OUTBUF=BUFFER_DESC,;return ASCII character
P1=RESULT
50
;in output string
51

PATCH-94

PATCH
Examples

006D
006D
0078
0085
0089
008A

52 ;output result
M0VAB
53
$PUT
54
M0VZBL
55
56
RET
57
.END

BUFFER,TRMRAB+RAB$L_RBF
RAB=TRMRAB
#SS$_NORMAL,RO
ENTRY.POINT

The program will assemble and link, but when executed will produce erro¬
neous results, as follows:
$ MACRO/DEBUG NEGATION.MAR;1
$ LINK/DEBUG NEGATION.OBJ;1
$ RUN/NODEBUG NEGATION.EXE;1
Enter decimal integer 25
The negation is 25.
$

Locate the incorrect code, by using the VAX/VMS Symbolic Debugger
or simply by examining the listing. You can invoke PATCH to make a
permanent change in the image file as shown below. The numbers to the
right of the example are keyed to the explanations that follow the example.
$

PATCH NEGATION.EXE;1

PATCH VERSION 4-00 15-Apr-1984
PATCH> SET ECO 1

PATCH> SET MODULE/ALL ©
PATCH> SET SCOPE NEGATION O
PATCH> SET MODE INSTRUCTION ©
PATCH> EXAMINE R0_C0DE+43
NEGATION
PATCH> REPLACE NEGATI0N\R0_C0DE+43
©
0LD> 'MOVL L~NEGATION\INTEGER,L~NEGATION\RESULT'
0LD> EXIT
NEW> 'MNEGL L~NEGATI0N\INTEGER,L~NEGATION\RESULT1
NEW> EXIT
old: NEGATION
new: NEGATION
PATCH> UPDATE ©
7.PATCH-I-WRTFIL, updating image file DB1: [GARTH]NEGATION.EXE;2
PATCH> EXIT ©
$

O Invoke PATCH—Invoke PATCH for an interactive terminal session by
typing the DCL command line PATCH NEGATION.EXE; 1. PATCH, in
return, displays an introductory message on your terminal. This message
indicates the version of PATCH that you are using and its release date.
© Define an ECO level—The SET ECO command defines the ECO level for
the ensuing patch. Note that the ECO level is not set until you issue the
UPDATE command.
© Alter the symbol status—The SET MODULE/ALL command inserts
all local symbol information into the symbol table, provided that you
followed the rules for passing local symbols at compile or assembly and
link time.
© Alter the scope status—The SET SCOPE command changes the contents
of the scope. In this case, the scope has been set to the module named
NEGATION.
© Alter entry and display mode status—The SET MODE command sets the
INSTRUCTION mode, causing PATCH to display the contents of the
specified locations as VAX MACRO instructions.

PATCH-95

PATCH
Examples

© Change the code—A number of PATCH commands can be used to modify
code. Each command alters the code in a unique fashion. In this example,
the REPLACE command was used to overwrite the existing instruction
with a new, correct instruction.
© Set the ECO level and update the image file—After you correct the code,
issue the UPDATE command. This sets the specified ECO level and
applies the patch to a new version of the image file.
© Exit from PATCH—Type the EXIT command to end the PATCH session
and return control to the VAX/VMS command interpreter.
Now run the program NEGATION.EXE;2 and it will execute properly.
$ RUN/NODEBUG NEGATION.EXE;2
Enter decimal integer 37
The negation is -37.
$

PATCH-96

Index

/ABSOLUTE qualifier • PATCH-31, PATCH-34
Addressing mode, forced-immediate*PATCH-25
ALIGN command*PATCH-22, PATCH-42,
PATCH-43
with /ABSOLUTE qualifier*PATCH-31
/ALL qualifier
in SET MODULE command • PATCH-80
Applying patches*PATCH-9
Arithmetic expression
evaluating • PATCH-62
special operators for*PATCH-28
ASCII string, entering*PATCH-25
/ASCII-/NOASCII qualifier
in DELETE command • PATCH-57
in DEPOSIT command • PATCH-60, PATCH-61
in EVALUATE command • PATCH-63
in EXAMINE command*PATCH-66
in REPLACE command*PATCH-74
in SET MODE command*PATCH-78
in VERIFY command • PATCH-92
ASCII-NO ASCII mode* PATCH-19

B
Branch instruction
calculating the location for*PATCH-71
calculating the relative displacement for*
PATCH-71
BYTE mode • PATCH-20
/BYTE qualifier
n ALIGN command*PATCH-42
n DELETE command • PATCH-56
n DEPOSIT command*PATCH-59, PATCH-61
n EVALUATE command • PATCH-62
n EXAMINE command • PATCH-65
n REPLACE command • PATCH-73
n SET MODE command • PATCH-78
n VERIFY command*PATCH-91

CANCEL MODE command • PATCH-44
CANCEL MODULE command • PATCH-45
CANCEL PATCH_AREA command • PATCH-23,
PATCH-47
CANCEL SCOPE command • PATCH-48
CHECK ECO command*PATCH-49, PATCH-50
CHECK NOT ECO command • PATCH-51
Command
See PATCH commands
Command descriptions*PATCH-42 to PATCH-92
Command procedure • PATCH-6 to PATCH-8,
PATCH-37 to PATCH-38
created using CREATE command • PATCH-6,
PATCH-52
created using text editor*PATCH-7
file specification*PATCH-52
processing selected patches in*PATCH-37 to
PATCH-38
using DEFINE command in*PATCH-7
using symbolic references in*PATCH-6 to
PATCH-8
using user-defined symbols in*PATCH-7
Comment, entering a*PATCH-28
Context modes*PATCH-18
See also Entry and display mode
CREATE command*PATCH-6, PATCH-52

D
DECIMAL mode*PATCH-20
/DECIMAL qualifier
in DELETE command • PATCH-56
in DEPOSIT command • PATCH-59
in EXAMINE command • PATCH-65
in INSERT command • PATCH-70
in REPLACE command • PATCH-74
in SET MODE command • PATCH-78
in VERIFY command*PATCH-91
Default file specification
See also File specification

Index—1

Index

Default file specification (cont'd.)
journal file*PATCH-33
output image file*PATCH-36
Default patch area*PATCH-22
DEFINE command • PATCH-7, PATCH-15, PATCH54, PATCH-55
DELETE command*PATCH-56 to PATCH-58,
PATCH-62
Delimiter*PATCH-19, PATCH-25, PATCH-28
DEPOSIT command*PATCH-59 to PATCH-61
in patch area operations*PATCH-21
/PATCH_AREA • PATCH-24, PATCH-61
with VERIFY command • PATCH-92
Descriptor, patch area*PATCH-21
Device driver image*PATCH-6, PATCH-22
Directing output of PATCH*PATCH-1
Display modes
See Entry and display modes

Entry and display modes (cont'd.)
WORD mode*PATCH-20
EVALUATE command • PATCH-62 to PATCH-64
EXAMINE command*PATCH-65 to PATCH-67
Examples
See also PATCH command (DCL), qualifiers
See also PATCH commands
See also Using symbols
interactive patch session*PATCH-93
Executable image*PATCH-5
EXIT command*PATCH-10, PATCH-68
Exiting PATCH • PATCH-1

F
File specification
See also Default file specification
in a command procedure*PATCH-52

G
ECO level*PATCH-9
See also PATCH commands
checking*PATCH-49, PATCH-50, PATCH-51
setting*PATCH-37, PATCH-38, PATCH-77
Engineering change order (ECO) level
See ECO level
Entry and display modes*PATCH-18
ASCII-NOASCII mode*PATCH-19
BYTE mode*PATCH-20
cancelling • PATCH-44
DECIMAL mode*PATCH-20
displaying location contents*PATCH-65
displaying mode*PATCH-86
GLOBALS-NOGLOBALS mode*PATCH-20
HEXADECIMAL mode • PATCH-20
INSTRUCTION-NOINSTRUCTION mode*
PATCH-19
length modes*PATCH-20
LONG mode*PATCH-20
mode qualifier, PATCH command*PATCH-18
OCTAL mode • PATCH-20
radix modes*PATCH-20
SCOPE-NOSCOPE mode*PATCH-20
setting the mode*PATCH-78
symbol search mode*PATCH-20
SYMBOLS-NOSYMBOLS mode*PATCH-19

Index—2

Global symbol*PATCH-11
/GLOBALS-/NOGLOBALS qualifier
in DELETE command • PATCH-57
in DEPOSIT command*PATCH-60
in EXAMINE command*PATCH-66
in INSERT command • PATCH-71
in REPLACE command*PATCH-74
in SET MODE command*PATCH-79
in VERIFY command*PATCH-92
GLOBALS-NOGLOBALS mode*PATCH-20

H
HELP command*PATCH-69
HEXADECIMAL mode*PATCH-20
/HEXADECIMAL qualifier
in DELETE command • PATCH-56
in DEPOSIT command • PATCH-60
in EVALUATE command • PATCH-62
in EXAMINE command • PATCH-66
in INSERT command*PATCH-70
in REPLACE command*PATCH-74

Index

/HEXADECIMAL qualifier (cont'd.)
in SET MODE command • PATCH-78
in VERIFY command • PATCH-91

I
/INITIALIZE qualifier •PATCH-23
in SET PATCH-AREA command • PATCH-81 to
PATCH-84
Input image file*PATCH-5
device driver image*PATCH-6
executable • PATCH-5
shareable • PATCH-5
INSERT command*PATCH-70 to PATCH-72
compared with DEPOSIT command*PATCH-60
with /ABSOLUTE qualifier*PATCH-31
with /INSTRUCTION qualifier*PATCH-24,
PATCH-71
/INSTRUCTION-/NOINSTRUCTION qualifier
in DELETE command*PATCH-57
in DEPOSIT command*PATCH-60, PATCH-61
in EVALUATE command*PATCH-63
in EXAMINE command • PATCH-66
in INSERT command*PATCH-70
in REPLACE command*PATCH-74
in SET MODE command*PATCH-78
in VERIFY command • PATCH-92
INSTRUCTION-NOINSTRUCTION mode*PATCH19
Interactive processing of selective patches*
PATCH-38
Invoking PATCH*PATCH-1

j
Journal file*PATCH-9
/JOURNAL qualifier*PATCH-33

L
Length modes*PATCH-20
See also Entry and display modes
Local symbol*PATCH-11

LONG mode*PATCH-20
/LONG qualifier
in ALIGN command • PATCH-42
in DELETE command*PATCH-56
in DEPOSIT command*PATCH-59
in EVALUATE command • PATCH-62
in EXAMINE command • PATCH-65
in REPLACE command • PATCH-73
in SET MODE command • PATCH-78
in VERIFY command • PATCH-91

MACRO
See VAX MACRO instruction
Mode qualifier, PATCH command*PATCH-18,
PATCH-78

/NEW—VERSION qualifier*PATCH-34
Numeric data, entering • PATCH-27

o
OCTAL mode*PATCH-20
/OCTAL qualifier
in DELETE command*PATCH-56
in DEPOSIT command • PATCH-59
in EVALUATE command • PATCH-62
in EXAMINE command • PATCH-65
in INSERT command • PATCH-70
in REPLACE command • PATCH-73
in SET MODE command • PATCH-78
in VERIFY command*PATCH-91
Opcode, VAX MACRO instructions with same*
PATCH-26
Operator • PATCH-28
for addressing locations*PATCH-29
for arithmetic expressions*PATCH-28
Output image file*PATCH-8, PATCH-36, PATCH
90
/OUTPUT qualifier*PATCH-9, PATCH-36

Index—3

Index

/PAGE qualifier
in ALIGN command*PATCH-42
Parameter value, delimiting a*PATCH-28
Patch area*PATCH-21 to PATCH-23, PATCH-81
to PATCH-84
allocate space*PATCH-42

/QUAD qualifier

commands that affect • PATCH-23
creating and accessing • PATCH-23
default* PATCH-22
depositing new data or instructions*PATCH59, PATCH-61
descriptor*PATCH-21, PATCH-81
displaying size and starting address*PATCH-88
/INITIALIZE qualifier*PATCH-81 to PATCH-84
inserting new instructions*PATCH-70 to
PATCH-72
patch area symbols*PATCH-21, PATCH-42
resetting*PATCH-23, PATCH-47
setting user-defined patch area • PATCH-81 to
PATCH-84
starting address*PATCH-42
used with device driver images*PATCH-22
used with shareable images*PATCH-22
user-defined*PATCH-22 to PATCH-23,
PATCH-82 to PATCH-84
Patch area symbol*PATCH-21
created with ALIGN*PATCH-22
reserved by DIGITAL*PATCH-21
PATCH command (DCL) • PATCH-1
qualifiers*PATCH-30 to PATCH-40
PATCH commands*PATCH-42 to PATCH-92
for expressing symbols and pathnames*
PATCH-17
rules of syntax for*PATCH-25 to PATCH-29
Patch, applying a*PATCH-9
/PATCH_AREA qualifier • PATCH-21, PATCH-24
See also DEPOSIT command
in DEPOSIT command • PATCH-60, PATCH-61
Pathname • PATCH-15
commands that affect • PATCH-17
determining value of*PATCH-63
Prompt
ECO level*PATCH-49, PATCH-51
ending repetitive*PATCH-68

Index—4

in ALIGN command • PATCH-42
Qualifiers
for DCL command • PATCH-30 to PATCH-40
mode, PATCH command*PATCH-18

R
Radix modes*PATCH-20
See also Entry and display modes
Radix operator*PATCH-20
REPLACE mmand* PATCH-73 to PATCH-76
compared with DEPOSIT command • PATCH-60
with /INSTRUCTION qualifier*PATCH-24,
PATCH-74
Rules of syntax*PATCH-25

s
Sample PATCH session*PATCH-93 to PATCH-96
Scope
canceling • PATCH-48
displaying current setting • PATCH-89
setting • PATCH-85
/SCOPE-/NOSCOPE qualifier
in DELETE command • PATCH-57
in DEPOSIT command • PATCH-60
in EXAMINE command*PATCH-66
in INSERT command*PATCH-71
in REPLACE command • PATCH-74
in SET MODE command • PATCH-79
in VERIFY command*PATCH-92
SCOPE-NOSCOPE mode*PATCH-20
SET ECO command*PATCH-9, PATCH-77,
PATCH-90
SET MODE command*PATCH-78 to PATCH-79
SET MODULE command • PATCH-80
SET PATCH_AREA command • PATCH-81 to
PATCH-84
creating and accessing patch area*PATCH-23

Index

SET PATCH-AREA command (cont'd.)
/INITIALIZE qualifier• PATCH-82, PATCH-83,
PATCH-84
SET SCOPE command • PATCH-85
Shareable image*PATCH-5, PATCH-22

SHOW MODE command*PATCH-86
SHOW MODULE command • PATCH-87
SHOW PATCH-AREA command • PATCH-88
SHOW SCOPE command*PATCH-89
Symbol*PATCH-10 to PATCH-17
commands that affect*PATCH-17
created with the DEFINE command • PATCH-15,
PATCH-54, PATCH-55
determining value of*PATCH-63
entering into symbol table*PATCH-80

/SYMBOLS-/NOSYMBOLS qualifier (cont'd.)
in VERIFY command*PATCH-92
SYMBOLS-NOSYMBOLS mode*PATCH-19
Syntax rules for patch commands • PATCH-25 to
PATCH-29
delimiting parameter values*PATCH-28
entering ASCII data strings*PATCH-25
entering comments*PATCH-28
entering numeric data • PATCH-27
entering VAX MACRO instructions • PATCH-25
operators for addressing locations • PATCH-29
operators for arithmetic expressions • PATCH28
VAX MACRO instructions with same opcodes*
PATCH-26

global* PATCH-11
local* PATCH-11
module name*PATCH-11
passing • PATCH-10
patch area*PATCH-21, PATCH-42
PATCH symbol table*PATCH-10
pathname • PATCH-15
program section name*PATCH-11
removing from symbol table*PATCH-45
routine name*PATCH-11
symbolic instruction label*PATCH-12 to
PATCH-14
translating address value into*PATCH-17
translating into address values*PATCH-16,
PATCH-20
universal • PATCH-11, PATCH-12
Symbol search mode*PATCH-20
See also Entry and display mode
Symbol table*PATCH-10, PATCH-15
Symbolic instruction label • PATCH-12 to PATCH14
function of*PATCH-12
side effects when using patch*PATCH-12 to
PATCH-14
Symbolic names
assigning to starting address*PATCH-22,
PATCH-42
creating • PATCH-54
/SYMBOLS-/NOSYMBOLS qualifier
in DELETE command*PATCH-57
in DEPOSIT command • PATCH-60
in EXAMINE command*PATCH-66
in INSERT command • PATCH-70
in REPLACE command • PATCH-74
in SET MODE command • PATCH-78

T
Text editor
creating command procedure with*PATCH-7
Translation
of addresses to symbols*PATCH-17
of symbols to addresses*PATCH-16

u
Universal symbol • PATCH-11, PATCH-12
declaring • PATCH-11
referencing in a shareable image • PATCH-11,
PATCH-12
UPDATE command*PATCH-8, PATCH-10,
PATCH-34, PATCH-90
/UPDATE qualifier*PATCH-37 to PATCH-39
User-defined patch area • PATCH-22 to PATCH23, PATCH-82 to PATCH-84
accessing with SET PATCH_AREA • PATCH-82
creating and accessing • PATCH-23
default size*PATCH-83
resetting*PATCH-23, PATCH-47
terminating use of*PATCH-23
when to use*PATCH-22
User-defined symbol • PATCH-7
Using entry and display modes • PATCH-18
Using patch area • PATCH-21
Using symbols*PATCH-10 to PATCH-17

Index—5

Index

V
VAX MACRO instruction
entering • PATCH-25
INSERT command •PATCH-70
with same opcode*PATCH-26
VERIFY command • PATCH-91 to PATCH-92
/VOLUME qualifier*PATCH-40

w
WORD mode*PATCH-20
/WORD qualifier
in ALIGN command*PATCH-42
in DELETE command • PATCH-56
in DEPOSIT command • PATCH-59
in EVALUATE command*PATCH-62
in EXAMINE command*PATCH-65
in REPLACE command*PATCH-73
in SET MODE command*PATCH-78
in VERIFY command • PATCH-91

Index—6

VAX/VMS
Patch Utility
Reference Manual
AA-Z426A-TE

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