Digital PDFs

AA-M507A-TC

January 1982

76 pages

Original

3.1MB

Document:	IAS/RSX-11 ODT Reference Manual
Order Number:	AA-M507A-TC
Revision:	0
Pages:	76
Original Filename:	http://bitsavers.org/pdf/dec/pdp11/rsts_e/V09/7_MACRO_Programming/AA-M507A-TC_IAS_RSX_V4.0_ODT_Reference_Manual_Jan82.pdf

OCR Text

IAS/RSX-11
ODT Reference Manual
Order No. AA-MS07 A-TC

RSX-11 M Version 4.0
RSX-11 M-PLUS Version 2.0
lAS Version 3.1

digital equipn1ent corporation · maynard, massachusetts

First Printing, December 1975
Revised, May 1977
Revised, January 1982
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 documentfi
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.

(§) 1975, 1977, 1978, 1982 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
DECnet
DECsystem-10
DECSYSTEM-20
DECUS
DECwriter
DIBOL

EduSystem
IAS
MASSBUS
PDP
PDT
RSTS

RSX
UNIBUS
~X

VMS
VT

ZK2062

CONTENTS

Page
PREFACE

vii

SUMMARY OF TECHNICAL CHANGES

CHAPTER 1

INTRODUCTION TO ODT

1.1
OVERVIEW OF ODT • • • • • • • • •
.•••• •
1.2
LINKING ODT WITH A USER PROGRAM • • • • • • • • •
1.2.1
Linking ODT from MCR • • • •
• • • • •
1.2.2
Linking ODT from DCL • • • • •
•
1.2.3
Linking ODT Using lAS PDS
• • • • •
1.2.4
Linking to Enable RSX-11M-PLUS Features
•
1.2.4.1
Enabling Instruction and Data Space
(RSX-11M-PLUS only) • • • • • •
•
1 •. 2 • 4 • 2
Enabling Supervisor-Mode Library Debugging
(RSX-I1M-PLUS only)
••••••
• •
1.3
INVOKING ODT • • • • • • • • • • • • • • • • • • •
1.4
RETURNING CONTROL TO THE HOST SYSTEM • • • • • • •
1.5
INTERRUPTING A DEBUGGING SESSION • • • • • • • • •
1.~;.1
Resuming a Debugging Session (RSX-I1M-PLUS)
••
1.5.2
Resuming a Debugging Session (lAS) • • • • • • •
CHAPTER 2
2.1
2.2
2.2.1
2.'2.2
2.3
CHAPTER 3
3.1
3.1.1
3.1.2
3.2
3.3
3.4
3.5
CHAPTER 4
4.1
4.2
4.3
4.3.1
4.3.2
4.3.3

1-1
1-2
1-2
1-3
1-3
1-3
1-3
1-4
1-4
1-4
1-5
1-5
1-5

ODT CHARACTERS AND SYMBOLS
VARIABLES USED IN COMMAND DESCRIPTIONS • • • • • •
ADDRESS EXPRESSION FORMATS • • • • •
•
Absolute and Relative Addressing •
• ••••
Forming Expressions
••••••••.
•
OPERATOR AND COMMAND SUMMARY •
• • • • • •

2-1
2-2
2-2
2-3
2-4

CONTROLLING PROGRAM EXECUTION
SETTING AND REMOVING BREAKPOINTS •
Setting Breakpoints
••••••••
Removing Breakpoints • • • •
BEGINNING PROGRAM EXECUTION
••••• • • • •
CONTINUING PROGRAM EXECUTION .
USING THE BREAKPOINT PROCEED COUNT
STEPPING THROUGH THE PROGRAM
•

3-1
· • 3-1
• • 3-2
• • 3- 2

· . 3-3
• 3-4
• • 3-4

DISPLAYING AND ALTERING THE CONTENTS OF LOCATIONS
ALTERING THE CONTENTS OF A LOCATION
CLOSING A LOCATION • • • • • • • • •
OPENING WORD AND BYTE LOCATIONS
• • • •
The a/ and a\ Commands • • • •
.
The / and \ Commands • • • • • • • • .
Moving Between Word and Byte Modes • .
i 1. i

.
.••••
. •
• . • • •
• . • • •
• ••

4-1
4-2
4-2
4-2
4-3
4-3

CONTENTS
Page
4.4
4.5
4.~

4.7
4.8
4.9
4.10
4.10.1
4.10.2
CHAPTER 5

OPENING THE NEXT SEQUENTIAL LOCATION . • • • • • •
OPENING THE PRECEDING LOCATION •
•••• • • •
OPENING ABSOLUTE LOCATIONS • •
• • • • • • •
OPENING PC-RELATIVE LOCATIONS
• • • •
OPENING RELATIVE BRANCH OFFSET LOCATIONS •
•
RETURNING FROM A CALCULATED LOCATION •
• •
US ING DI FFERENT OUTPUT MODES •
••••
•
ASCII Mode • • •
Radix-50 Mode
•••••
USING REGISTERS

5.1
GENERAL REGISTERS
••••••••••••
• •
5.1.1
Examining and Setting General Registers
•
5.1.2
Contents of General Registers
•
5.2
ODT INTERNAL REGISTERS • • • • • • • • • . • • • •
5.2.1
Relocation Registers • • • •
• • • • •
Setting Relocation Registers • •
5.2.1.1
•
5.2.1.2
Clearing Relocation Registers
••••
• •
5.2.2
The Reentry Vector Register
•••.
• •
0

CHAPTER 6
6.1
6.1.1
6.1.2
6.1.'3
6.1.4
6.2
6.2.1
6.2.2
6.2.3
6.3
6.4
6.4.1
6.4.2
CHAPTER 7
7.1
7.2
7.3
7.3.1
7.3.2
7.3.3
7.3.4
7.3.5
CHAPTER 8

4-4
4-'4
4-4
4-5
4-5
4-6
4-6
4-6
4-7

•

5-1
5-1
5-2
5-2
5-6
5-6
5-6
5-7

MEMORY OPERATIONS
REGISTERS USED IN MEMORY OPERATIONS
• • • •
..6-1
Search Limit Registers • • •
6-1
Search Mask Register • • • • •
• • • • • • 6-2
Search Argument Register • • • • • • • • • • • • 6-2
Device Control LUN Registers
• • • • • • • 6-2
SEARCHING MEMORY • • • • • • •
• • 6-3
Searching for a Word or Byte •
• • • • 6-3
Searching for Inequality of a Word or Byte •
6-3
Searching for a Reference
••••
• 6-3
FILLING MEMORY •
• • • • 6-4
LISTING MEMORY • • • • •
• 6-4
Command Format •
• • ••
• • 6-4
Listing Format •
. • • • • . • • • • • • • • 6-5
0

• • • • • • • • •

PERFORMING CALCULATIONS
CALCULATING RELOCATABLE ADDRESSES
• 7-1
CALCULATING OFFSETS
• 7-1
EVALUATING EXPRESSIONS • • • •
7-2
Equal Sign Operator
• • • 7-2
Current Location Indicator •
• 7-3
Constant Register Indicator
• • • • • • • • • • 7-3
Quantity Register Indicator
••••
• • 7-3
Radix-50 Evaluation
•••••
• • 7-4
ADDITIONAL DEBUGGING AIDS

8.1
ACCESSING OTHER DEBUGGING AIDS
• • • • • • 8-1
8.1.1
MCR Command Line • • • • •
• • • • • • • • 8-1
8. 1 • 2
DCL Command Line • • • • •
• 8-1
8. 1 .3
lAS PDS Command Line • • •
• • • • • • 8- 2
8.2
THE TRACE DEBUGGING PROGRAM
• 8-2
8.2.1
The Trace Listing
••••
• 8-2
8.2.2
Bias Values and Ranges • • • • • • • •
• • 8-3
8.2.2.1
Specifying a Bias Value
• • • 8-3
8.2.2.2
Specifying Ranges to be Traced
• 8-3

CONTENTS
Page
APPENDIX A

ERROR DETECTION

A.1
A.2

INPUT ERRORS • •
TASK IMAGE ERROR CODES

APPENDIX B

PROCESSOR STATUS WORD

• A-I
• A-2

INDEX

EXAMPLES
EXAMPLE 6-1

8-1

ODT Listing Format •
Sample Trace Output

• • 6-5
• • 8-3

FIGURES
FIGURE

B-1

Format of the Processor Status Word

• • • • • • • B-1

TABLES
TABLE

2-1
2-2
2-3
5-1
5-2
7-1

Variables Used in ODT Command Descriptions •
• 2-1
Forms of Address Expressions
2-4
aDT Operators and Commands • • • • • • • • •
• 2-4
aDT Single Registers • • • • • • • • • • •
• • 5-3
aDT Register Sets
• • • • • • • • • • • • • • 5-4
Numeric Equivalents of Radix-50 Characters •
7-4

PREFACE

MANUAL OBJECTIVES
This manual describes the On-Line Debugging Tool,
ODT-ll,
used to
debug
user task images on RSXII-M, RSX-IIM-PLUS, and lAS systems.
It
provides reference information on all ODT commands,
plus information
on how to use the commands to debug user task images.

INTENDED AUDIENCE
This manual is intended for all systems and applications programmers
who develop task images under the RSX-IIM,
RSX-IIM-PLUS, or lAS
ope~ating systems.
Readers should understand the user
interface of
the operating system that they are using.
RSX-IIM and RSX-IIM-PLUS
users should be familiar with the contents of the RSX-IIM/M-PLUS Guide
to Program Development before reading this manual.

STRUCTURE OF THIS DOCUMENT
This manual is divided into eight
follows:

chapters

and

two

appendixes,

Chapter I, Introduction to ODT, gives an overview of ODT.
It then
explains how to link the debugger into a user task image and how to
begin and end a debugging session.
Chapter 2, aDT Characters and Symbols, explains the special symbols
used in ODT and
includes a reference table of all ODT commands, in
alphabetical order.
Readers who are approachingODT for the first
time should read Chapters 3 through 7 for explanations of the commands
before studying the table of commands in detail.
Experienced ODT
users can use Chapter 2 by itself for quick reference.
Chapter 3, Controlling Program Execution, describes the command used
to begin program execution, to stop execution at breakpoints, and to
continue execution after breakpoints.
It also explains how to execute
a program one or more instructions at a time.
Chapter 4, Displaying and Altering the Contents of Locations, explains
how to open and close task locations, how to change the contents of
locations, and how to display the contents of locations in different
modes.
Chapter 5, Using Registers, describes all of the registers used by
ODT.
It includes reference tables as well as explanations of how
registers are set and cleared.
Experienced ODT users may wish to
consult the tables in this chapter, as well as those in Chapter 2, for
quick reference regarding specific registers.

vii

PREFACE
Chapter 6, Memory Operations, describes ODT's memory search, fill, and
list capabilities.
Chapter 7, Performing Calculations,
perform arithmetic calculations.

describes

how

use

ODT

Chapter 8, Additional Debugging Aids, explains how to link debuggers
other than ODT into a user task
image.
It describes the Trace
program, a debugging aid that can be used in conjunction with ODT.
Appendix A, Error Detection, describes how ODT responds to errors in
user
input or program logic.
It lists all ODT error message codes in
alphabetical order.
Appendix B, Processor Status Word, shows the format
summarizes the functions of its bits.

the

PSW

and

ASSOCIATED DOCUMENTS
The documentation directory of the host operating system
other manuals that will be of interest to ODT users.

describes

CONVENTIONS USED IN THIS DOCUMENT
Throughout this book symbols and other notation conventions are used
to
represent keyboard characters, to convey textual information, and
to aid the reader's understanding of material.
These symbols and
conventions are explained below.
Convention

Meaning
A symbol with a 1- to 3-character abbreviation,
such as
@
or
(BIT) , indicates that you press a
key on the terminal.
This phrase indicates that you press the key
labeled CTRL while simultaneously pressing another
key, such as C or Y.
In examples,
this control
key sequence is shown as AX (for example, AC or
Ay), because that is how the system displays it on
your terminal.

red ink

User input appears in red
ink in the examples
throughout this book.
aDT responses appear in
black ink.

shading

Gray shading
RSX-IIM-PLUS.

denotes

viii

information

spe61fL~

SUMMARY OF TECHNICAL CHANGES

This manual describes four new ODT commands for
systems:

use

Accesses data space

Accesses instruction space

Sets the current mode of COT to user mode

Sets the current mode of COT to supervisor mode

RSX-IIM-PLUS

This manual also corrects small technical errors in the text and
examples of the previous version.
It represents a significant
information
more
reorganization of material,
intended to make
available to readers.

CHAPTER 1
INTRODUCTION TO DDT

aDT, or On-line Debugging Tool,
images.
You can use aDT to:

utility

for

debugging

•

Control program"execution

•

Display the contents of locations or registers

•

Alter the contents of locations or registers

•

Search and fill memory

•

Perform calculations

task

DDT commands consist of one character;
some commands take a numeric
or alphabetic argument.
All aDT commands, and the symbols that are
used in them, are listed in Chapter 2.
Chapters 3 through 7 describe
how you use the commands.
This chapter
initiated.

1.1

introduces

aDT

and

describes

how

the

debugger

OVERVIEW OF DDT

aDT is special code that you link into your task image to help you
debug your program.
When you run a task into which aDT has been
linked,
the debugger receives control automatically
upon
task
initiation.
Then,
through aDT, you can execute your task gradually,
setting breakpoints at selected locations or stepping through the
program one instruction at a time.
Chapter 3 describes aDT commands
for controlling program execution.
You can examine any location in your program -- instruction or data,
word or byte -- by "opening" the location with DDT.
While the
location is open, you can immediately change the contents.
You can
proceed forwards or backwards to examine and modify other locations.
Thus, you can test any number of modifications without rebuilding your
task.
Chapter 4 describes aDT commands for examining and altering
locations and for moving from one location to another.
aDT operates through the use of a number of registers, all of which
you can set and reset.
Some of these registers are used to store
information about your program while aDT has control.
Eight registers
:an be set to the locations of breakpoints.
Eight can be set to
relocation biases -- the absolute base addresses of relocated object
nodules.
You can use other registers to store values that you may
~ant to use repeatedly
during your debugging session.
Chapter 5
jescribes the aDT registers.

1-1

INTRODUCTION TO ODT
You can use ODT to search for bit patterns in memory, to fill
blocks
of memory with a value, or to list blocks of memory on an output
device.
Chapter 6 describes these operations.
During a debugging session, you can perform a variety of calculations:
determining
offsets,
evaluating
arithmetic
expressions,
and
constructing Radix-50 words.
These calculations are described
in
Chapter 7.

1.2

LINKING ODT WITH A USER PROGRAM

ODT is provided on your system as an object module,
LB:[1,1]ODT.OBJ.
of OD,!, supporting the instructioh and"data::sp~n::!~":f"Era:t'U:t:(i:s:~
of :RSX"";11M-PLUS is provided in the object: module La,~"[):;(r43:QD!t,:ID;;:cfBa:;';:
To use ODT, you must link the appropriate object module with the"
object module(s) of your program. When the resulting
task
image is
run, ODT is invoked and initiated automatically.

~~he . "ver.si"on

If the task image is overlaid, ODT is linked into the root segment
that the debugger will always be available.

The following sections describe how to link ODT into a task
image in
different environments.
Section 1.2.1 describes how to link ODT if
your command line interpreter is MCRo
Section 1.2.2 describes how to
link ODT using
the DCL command line
interpreter.
Section 1.2.3
describes how to use the lAS Program Development System (PDS) to link
ODT into your task image.
Section 1.2.4 describes how to enable the
I- and D-space and supervisor-mode features of ODT used under
RSX-IIM-PLUS.
The information in subsequent sections on initiating
applies equally to all environments, except as noted.

1.2.1

and

using

ODT

Linking ODT from MCR

To link ODT with your program when your command line
interpreter
is
the Monitor Console Routine (MCR), you first invoke the Task Builder
by typing TKB in response to the MCR prompt.
The Task Builder replies
with
its own prompt, TKB>.
In response to this prompt, enter a Task
Builder command specifying the name of the
file(s)
to be linked.
Include the /DA switch, which indicates that a debugger (in this case
ODT, the default) should be linked
into the
image.
The following
example shows the resulting command line:
TKB>MYTASK/DA=MYFILEl,MYFILE2
The Task Builder accesses the file ODT.OBJ in UFO [1,1] on the library
device and
links
it with the files MYFILE1.0BJ and MYFILE2.0BJ into
the task MYTASK.
Using ODT requires that you consult an up-to-date map of your task.
Therefore,
you should in most cases request a new map when you build
the task, as in the following command line:
TKB>MYTASK/DA,MYTASK/CR/-SP=MYFILEl,MYFILE2
For more
information on using
the Task Builder,
consult
the
RSX-IIM/M-Plus Task Builder Manual or the lAS Task Builder Reference
Manual, as appropriate for your system.
--- ----

1-2

INTRODUCTION TO ODT
1.2.2

Linking ODT from DCL

To link ODT with your program(s) when your command line interpreter is
the DIGITAL Command Language (DCL) , use the /DEBUG qualifier with the
LINK command.
To obtain a current map of the image file produced, you
should also
include the /MAP qualifier.
The following example shows
the resulting command line:
>LINK/MAP/DEBUG/TASK:MYTASK MYFILEl,MYFILE2
Object modules MYFILEl.OBJ and MYFILE2.0BJ are linked with object
module ODT.OBJ in UFD [1,1] on the library device.
The resulting task
image is named MYTASK.TSK.
For further information on
Command Language ~anual.

1.2.3

using

DCL,

consult

the

RSX-llM/M-PLUS

Linking ODT Using lAS PDS

To link your program(s) with the lAS Program Development System, enter
the LINK command with the /DEBUG switch in response to the PDS prompt.
To obtain a map of the image file produced, include the /MAP switch as
well.
The following example shows the resulting command line:
PDS> LINK/MAP/DEBUG MYFILE
This command links the object module MYFILE.OBJ with the object module
ODT.OBJ from LB:[l,l] to produce the task image MYFILE.TSK.
For more information on linking
Builder Reference Manual.

under

1-3

lAS,

consult

the

lAS

Task

INTRODUCTION TO ODT

:i:f<.;Yoit'r:'CLils ,DCL, ,you enable instruction and data'. Space"c.om~:~~'&$<;i:;b:~rJ'
:U:$'il1g>'th'~',qualifier/CODE:DATA_SPACE, as well as the IbE8,UG'q:ucf~r~1~fi~(:::S
,w~'th,~hel.lNI< comllland.
The following example shows ,the<"~:r~'$iq:t,f'i):<.t~~:

li<)~nf~;:J~;;:fauGICope:

>:~',,~;,~;·jc;;;;'
YQ'c.;ca nllddo the rqual i f i ers g
to the LINK command, as d escr1J:i~i:lf<fr';~:-:t~ZS:

DA TA_SPA E MYTAS K

r:k:~::~::::~::::ma::n La:::: eo::::~~~J explicitly, sp~Cif,Y~~~·%~r2%~

'p,a:pj.1'9ger, object 'module in the MCR or DCL' command 1, ina;_,' .'.'~o::'do',:~~;'§\',,:>;<
J<>llo\.t>~he procedure :described in Sections 8.1.1 ,and 8'.1~~:;2~ ::,>j*~,,':";::';\>2:'::":"~»:;

}.~~':4:.C2:;:,~na trig Supervisor-Mode LIbrary Debuggl ng( MX~:lM2~t~i}liij;~I
bl

':::'~\'Ori"",RSX""'llM"':'PLUS

'li'pr:ar·ies..

systems, you can use ODT todebug,',super\rl$or:~in9,C\:~);;:
To enable the Z command, you must link Y(,)\lr,>p~Q~'t:'a'm):;;'?I'Sr<~:

!:s::::::o::::c:~:nb:::~;~::ts or write into tbesuj~~vi¥~ii~~'~~'

Jtbiarlesj·· you must ,install the library READ/WRITE,' or QuJ:ld::·.tbe:;·,.:b~:jiJ<::;~.
"~:s pr lvlJ.,ege :
0.·
. •'
, ::;':>'":" '~;,)~<:,>:"
<~.

1.3

","

>., ~,' .; .'. ",~'._~:.-<-h:-",:

,~~><:~'-«

INVOKING ODT

ODT is invoked automatically when you run a task image into which aDT
has been linked, as described in the previous sections. Regardless of
what operating system or CLI you use, enter the RUN command,
specifying the name of the task image file.
aDT responds with a message indicating that it has been invoked and
identifying the task image that it controls. On the next line, ODT
displays its prompt, an underscore( ), indicating that it is ready to
accept commands.
The following example (using
HIYA.TSK is run:

MCR)

shows

how

aDT

invoked

when

>RUN HIYA
ODT:TT15
In response to the aDT prompt, you can enter any ODT command.
ODT
commands are immediate-action commands; that is" ODT responds to the
commands as soon as they are typed, without waiting for a line
terminator.
Therefore, commands cannot be corrected once they have
been typed. You can, however, erase an incorrectly typed command
argument by typing an illegal character or command (such as 8 or 9),
or by typing
(CTRL/U)
or
(lli)
In response, ODT discards your input
line, displays a question mark (?), and prompts for another command.
Error detection is described in greater detail in Appendix A.

1.4

RETURNING CONTROL TO THE HOST SYSTEM

To return control from aDT to the host operating system, type X in
response to the aDT prompt.
This command causes execution of the
system Task Exit directive, which terminates task execution.

1-4

INTRODUCTION TO ODT
1.5

INTERRUPTING A DEBUGGING SESSION

When you run a task linked with ODT, you can return to the
line interpreter prompt at any time by typing
mRL/C).
Your
still active.
To stop execution of the task, enter the ABORT
in response to the MCR or DCL prompt.
You cannot resume the
debugging session; you can only run your program again.

command
task is
command
aborted

On RSX-llM-PLUS and lAS systems, you can interrupt task execution
without aborting your task and then continue debugging. After typing
~g
, use thE! commands described in the following sections, as
appropriate for your system.

1.5.2

Resuming a Debugging Session (lAS)

On an lAS time-sharing system using the PDS command line interpreter,
you can use the CONTINUE/DEBUG command to interrupt task execution and
return to the ODT prompt.
ODT responds with a TE error message,
showing the current value of the program counter as the locati~n where
the error occurred.

1-5

INTRODUCTION TO ODT
The following example shows how the CONTINUE/DEBUG command is used:
PDS> RUN MYFILE
ODT:TT5
G
AC
PDS> CONTINUE/DEBUG
TE:004020
Note that this command can be used only on a time-sharing system, not
on an lAS multiuser system.
For further information, consult the lAS
PDS User's Guide.

1-6

CHAPTER 2
ODT CHARACTERS AND SYMBOLS

This chapter presents all of the ODT operators and commands and
explains the meanIngs of ODT-specific symbols used in this book.
(Symbols common to the document set are presented in the Preface.)

2.1

VARIABLES USED IN COMMAND DESCR,IPTIONS

Table 2-3 and the command descriptions in Chapters 3 through 7 use
lO~lercase
alphabetic variables to represent numeric and alphabetic
arguments specified in commands.
These symbols are explained in Table
2-1.
Table 2-1
Variables Used in ODT Command Descriptions
Variable

Meaning

An address expression representing the address of a
task image location.
The various forms in which an
address expression can be specified are explained in
Section 2.2.

An octal value up to 6 digits long with a maximum
value of 177777(octal) , or an expression representing
such a value. An expression may include arithmetic
operators or indicators, as described
in Section
2.2.2.
If more than 6 digits are specified, ODT
truncates to the low-order 16 bits.
If the octal
value is preceded by a minus sign, ODT takes the
two's complement of the value.

An octal value six digits long, used to
search mask.

An octal integer in the range

An alphabetic character.
alphabetic characters is
the variable x is used.

2-1

represent

a through 7.

A list
of
permitted
given in the tables where

ODT CHARACTERS AND SYMBOLS
2.2

ADDRESS EXPRESSION FORMATS

represented throughout this manual by the
An address expression,
is an expression interpreted by ODT as a l6-bit
lowercase letter a,
(6-digit octal) value.
You use an address expression to refer to a
location in your task.
You can specify an address expression in either absolute or relative
(relocatable) form, as described in Section 2.2.1.
You can include in
the address expression various operators and symbols, as described
in
Section 2.2.2.

2.2.1

Absolute and Relative Addressing

Each location has an absolute address assigned to it when the task is
built.
You can refer to the location using this ry-digit octal value.
However, when the task is built again, with modules added or changed,
this value may not refer to the same location.
Therefore, it is often
more convenient to refer to locations using relative
(relocatable)
addressing,
which is less likely to be affected by subsequent task
builds.
When you use relative addressing, you refer to a location not by its
absolute value but by its position relative to a movable point.
Usually, this movable point is the base
(starting)
address of the
module to which the location belongs, because the distance between the
base address and the addresses of locations within the module is
easily determined from a
task map or listing and is not likely to
change without your knowledge.
The movable point can, however, be any
point that is convenient for debugging.
To use this form of addressing, you must first establish a simple
means of referring to movable points through the use of ODT's
relocation registers $RO through $R7.
Each time you run a task built
with ODT,
consult a task map to determine the absolute addresses of
convenient movable points.
The map's memory allocation synopsis
contains the base addresses of all the modules in the task.
Follow
the procedure described
in Section 5.2.1.1 to set ODT's eight
relocation registers to absolute addresses.
Once a relocation register is set, you can use the number
register, 0 through 7, in forming relative addresses.

that

through

A relative address has the following form:
n,k
n

The number of a
relocation
representing $RO through $R7.

A required separator
relative address.

the

parts

(comma)

2-2

between

two

the

ODT CHARACTERS AND SYMBOLS
k

The relative location,
the distance of the desired
location from the value contained
in register $Rn.
Usually, this is the location's position within the
module whose base address is the value of the register.
Thus, relative address 0,100 refers to location 100 within the module
whose base addr.ess is stored
in ODT's relocation register $RO.
Relative address 5,300 refers to location 300 within the module whose
base address is stored in relocation register $R5.
A general term for the value stored in a relocation register is "bias
value":
a quantity equal to the distance (bias) between a relative
location and its absolute address.
A general term for the second part
of a
relative address is "offset":
the distance of a relative
location from thE~ closest value (less than that location) stored in a
relocation register.
These terms are used throughout this manual.

2.2.2

Forming Expressions

An expression is a string of numbers, symbols, and operators that is
interpreted as a number.
For example, 3+6 is an expression;
ODT
would interpret it as the octal value 11.
You can use an expression to represent an absolute address, a register
containing a bias value, or an offset, as described in Section 2.2.1.
An expression used in an ODT session can contain any of the
elements:

following

•

Octal numbers.
ODT will not accept input containing an 8
9;
instead, it displays a question mark and a new prompt.

•

The arithmetic operators plus sign (+)
or space,
indicating
that values should be added, or minus sign (-), indicating
that the value that follows it should be subtracted from the
value that precedes it.

•

The unary operator minus sign (-), indicating that the value
that follows it is negative and should be interpreted in two's
complement form.

•

representing $Q and $C
ODT register
indicators Q or C,
registers,
as
described
in
Sections 7.3.3 and 7.3.4
register
respectively. When Q or C is used to represent a
containing a bias value, it must have a value in the range 0
through 7. When Q or C is used to represent an offset, it may
contain any l6-bit value.

•

The name of one of ODT's registers,
described in Chapters 5 and 6.

•

The current
7.3.2.

location

indicator

used

(.),

the

described

operations
in

Section

In evaluating expressions, ODT proceeds from left to right.
It does
not assign precedence to any operator, or recognize parentheses to
establish precedence.
Therefore, you must be careful to
form
expressions so that they will be interpreted correctly. You can use
the equal sign operator (=), described in Section 7.3.1, to determine
the value of expr.essions before using them in ODT operations.

2-3

ODT CHARACTERS AND SYMBOLS
Table 2-2 shows how ODT interprets the various forms of address
expressions.
This table assumes a value of 003400 for relocation
register 3 ($R3) and a value of 3 for the constant register ($C) ~
Table 2-2
Forms of Address Expressions
Address Expression
Input

2.3

ODT Octal
Interpretation

000005

-17

177761

3,150

003550

000003

C,lO

003410

C,C+C

003406

3,C

003403

Task general
register 3

OPERATOR AND COMMAND SUMMARY

ODT commands are made up of a combination of
letters.
Some commands have multiple forms.

symbols

and

uppercase

Table 2-3 summarizes the ODT commands and operators,
which are
explained
in detail
in Chapters 3 through 7.
The lowercase letters
used in the command descriptions are explained in Table 2-1.
Table 2-3
ODT Operators and Commands
Format

Meaning

+ or space

Arithmetic operator used
in expressions.
Add the preceding argument to the following
argument to form the current argument.
Arithmetic operator used
in expressions.
Subtract the following
argument from the
preceding argument to
form
the current
argument.
Also used as a unary operator to
indicate a negative value.

(comma)

Argument separator.
Separates the number
of a
relocation register from a relative
location to specify a relocatab1e address.
(continued on next page)

2-4

ODT CHARACTERS AND SYMBOLS
Table 2-3
(Cont.)
ODT Operators and Commands
Format

Meaning
Radix-50 separator used
in constructing
Radix-50 words (see Section 7.3.5).

Current location indicator.
Causes the
address
of the last explicitly opened
location to be used as the current address
for ODT operations.
Argument separator.
Separates
multiple
arguments,
allowing an address expression
or ODT register value to be identified.
~J)

kffil

location and
Closes the currently open
is
If
prompts for the next command.
ffil
the value k replaces the
preceded by k,
contents of the currently open location
before it is closed.
."

0['

Closes the currently open location, opens
the next sequential location (a word or a
byte,
depending on the mode in effect) and
displays its contents.
If
@
is preceded
by k, the value k replaces the contents of
the currently open location before it is
closed.

,. or k ...·

Closes the currently open location, opens
the
immediately preceding location and
displays its contents.
I f " is preceded by
k, the value k replaces the contents of the
currently open location before
it
is
closed.

or k

Interprets the contents of the currently
open location as a PC-relative offset and
calculates the address of the next location
to be opened;
closes the currently open
location,
and opens and
displays
the
contents
of
the
new
location
thus
evaluated.
If
is preceded by k, the value
k replaces the contents of the currently
open location before it is closed.

@ or k@

Interprets the contents of the currently
open word location as an absolute address,
closes the currently open location,
and
opens and displays the contents of the
absolute location thus evaluated.
If @ is
preceded by k,
the value k replaces the
contents of the currently open location
before it is closed.
(continued on next page)

2-!5

ODT CHARACTERS AND SYMBOLS
Table 2-3
(Cont.)
ODT Operators and Commands
Format

Meaning

> or k>

Interprets the low-order byte
of
the
currently open word location as a relative
branch offset, and calculates the address
of the next location to be opened;
closes
the currently open location, and opens and
displays
the contents of the
relative
branch location thus evaluated.
If > is
preceded by k,
the value k replaces the
contents of the currently open location
before it is closed.

< or k<

Closes the currently open location
(opened
by a
,@, or > command), and reopens the
word location most recently opened by a I,
@
,or~.
If the currently open location
was not opened by a
,
@, or >, then <
simply
closes and
reopens the current
location.
If < is preceded by k, the value
k replaces the contents of the currently
open location before it is closed.

Represents the address of one of eight
general
registers,
where n
is an octal
digit identifying RO through R7.

$x or $nx

Represents the address of one of ODT's
internal
registers,
where x is one of the
following alphabetic characters, and n
is
one octal digit.
Registers exist within
ODT in the following order:
S

Processor Status register
PS)

(hardware

Directive Status Word
the user's task

Search argument register

Search mask register

Low memory limit register

High memory limit register

Constant register

Quantity register

Format register

Reentry vector register

Breakpoint address registers

for

(continued on next page)

2-6

ODT CHARACTERS AND SYMBOLS
Table 2-3
(Cont.)
COT Operators and Commands
Format

Meaning
nG

Breakpoint proceed count registers

Breakpoint instruction registers

Relocation registers

SST vector registers

SST (synchronous system trap)
contents registers

stack

Device control LUN
number) registers

unit

(logical

" or a"

Word mode ASCII operator.
Interprets and
displays the contents of the currently open
(or the last previously opened) location as
two ASCII characters, and stores this word
in the quantity register
($Q).
If "
is
preceded by a, the value a is taken as the
address of the location to be interpreted
and displayed.

, or a'

Byte mode ASCII operator.
Interprets and
displays the contents of the currently open
(or the last previously opened) location as
one ASCII character, and stores this byte
in the quantity register
($Q).
If
is
preceded by a, the value a is taken as the
address of the location to be interpreted
and displayed.

% or a%

Word mode Radix-50 operator.
Interprets
and displays the contents of the currently
open
(or the last
previously
opened)
location as three Radix-50 characters, and
stores this word in the quantity register
($Q).
If % is preceded by a, the value a
is taken as the address of the location to
be interpreted and displayed.

/ or a/

Word mode octal operator.
Displays the
contents of the last word location opened,
and stores this octal word in the quantity
register
($Q).
If / is preceded by a, the
value is taken as the address of a word
location to be opened and displayed.

Byte mode octal operator.
Displays the
contents of the last byte location opened,
and stores this octal byte in the quantity
register
($Q).
If \ is preceded by a, COT
takes the value a as the address of a byte
location to be opened and displayed.

or a\

(continued on next page)

2-7

ODT CHARACTERS AND SYMBOLS
Table 2-3
(Cont.)
ODT Operators and Commands
Format

Meaning

Interprets and displays expression value k
as six octal digits and stores this word in
the quantity register ($Q).

8 or 9,
RUBOUT,
or (CTRLlU)

Cancels the current command and awaits a
new command.
The decimal value 8 or 9 is
not a legal character and thus,
when
entered,
causes ODT to ignore the current
command.
The RUBOUT and
©RL/U)
functions
are not operational in RSX-IIM unless the
terminal
driver
supports
transparent
read/write (a system generation option).

Removes all breakpoints from the user task.

Removes the nth breakpoint
task.

a;nB

Sets breakpoint n in the user task at
address a.
If n is omitted, ODT assumes
the lowest-numbered available sequential
breakpoint.

Constant regist.er
the
contents of
register) •

Accesses data space. Aft:e'r,:~~hTs;;Ooitim~na,:t~~::~
issued,
ODT interpr(~ts·a11:~i'e:'f:eJr;e:nc.~s::t~:!~
locations as ref err i r1~J,to ,th:e;', "n~$J,Ea:~H(:',:~~:::
the task (RSX-:IIM-PLUS only):.:,'::>:

from

the

user

Represents
indicator.
register $C
(constant
-i-'h",N

:+,::::;:':::::::::::::

E or kE
or m;E
or mikE

Searches memory between the address limits
specified by the low memory limit register
($L) and the high memory limit register
($H).
ODT examines these locations for
references
to
the
effective
address
specified in the search argument register
($A), as masked by the value specified
in
the search mask register ($M).
(The mask
should normally be set to 177777 for the E
command.)
Such references may be equal to,
PC-relative to, or a branch displacement to
the location specified
in $A.
If E is
preceded by k, the value k replaces the
current contents of $A before ODT initiates
the search.
If E is preceded by m,
the
current contents of $M are replaced with
the value m before ODT initiates
the
search.
(continued on next page)

2-8

ODT CHARACTERS AND SYMBOLS
Table 2-3
(Cont.)
ODT Operators and Commands
Format

Meaning

F or kF

Fills memory locations within the address
limits specified by the low memory limit
register ($L) and
the high memory limit
register
($H)
with the contents of the
search argument register
($A).
If
F is
preceded by k,
the value k replaces the
current contents of $A before ODT initiates
the fill operation.

G or aG

Begins task execution,
following
these
steps:
sets
BPT
instructions in or
restores BPT instructions to all breakpoint
locations
in the task image;
restores the
Processor Status Word and
user program
registers;
and starts execution at the
address specified by the program counter
(user register $7).
If G is preceded by a,
the value a replaces the current contents
of $7 before proceeding as described above.

Using
the
relocation
register
whose
contents are equal
to or closest to (but
less than) the address of the currently
open location,
ODT computes the physical
distance (in bytes) between the address of
the currently open location and the value
contained in that relocation register.
ODT
displays
this offset and stores the value
in the quantity register ($Q).

computes the physical distance
(in bytes)
between the address of the currently open
or the last-opened location and
the value
contained
in relocation
register n. ODT
displays this offset and stores the value
in the quantity register ($Q).

a;nK

computes the physical distance
(in bytes)
between address a and the value contained
in relocation register n. ODT displays this
offset and stores the value in the quantity
register ($Q).

L or kL
or ail
or a;kL

Lists all word or byte locations in the
task between the address limits specified
by the low memory limit register
($L)
and
the high memory limit register.
If L is
preceded by k, the value k replaces
the
current contents of $H before initiating
the list operation.
If L is preceded by a,
the value a replaces the current contents
of $L before initiating the list operation.
(continued on next page)
2-9

ODT CHARACTERS AND SYMBOLS
Table 2-3
(Cont.)
aDT Operators and Commands
Format

Meaning

~--------------~----------------------------.------------------------~

N or kN
or miN
or m;kN

Searches memory between the address limits
specified by the low memory limit register
($L) and
the high memory limit register
($H)
for
words with bit patterns that do
not match those of
the search argument
specified
in the search argument register
($A).
Only bit positions set to 1
in the
mask
are
compared.
This
search
is
identical in form and function to the word
(W) search described below, except that aDT
performs a test for inequality.

aO or a;kO

Calculates and displays the
PC-relative
offset and
the 8-bit branch displacement
from the currently open location to address
a;
or
calculates
and
displays the
PC-relative offset and
the 8-bit branch
displacement
from
the specified address a
to the specified address k.

P or kP

Proceeds with user program execution from
the current breakpoint location and stops
when the next breakpoint
location
is
encounter~d
or
the end of the program is
reached • . If k is specified,
aDT proceeds
with program execution from
the current
location and stops at the breakpoint only
after encountering
it the number of times
specified by integer k.

Quantity register
the
contents of
register} •

Sets all
relocation
registers
to
the
highest address value,
177777(octal) , so
that
they cannot be used
in
forming
addresses.

Sets relocation register n to
the highest
address value,
177777(octal) ,
so that it
cannot be used in forming addresses.

a;nR

Sets relocation register n to address value
a.
If n is omitted, aDT assumes relocation
register o.

S or nS

Executes one instruction and displays the
address of the next
instruction to be
executed.
If n is specified, aDT executes
n
instructions and displays the address of
the next instruction to be executed.

indicator.
Represents
register
$Q
(quantity

(continued on next page)

2-10

ODT CHARACTERS AND SYMBOLS
Table 2-3
(Cont.)
ODT Operators and Commands
Meaning

Format

Enables ODT's handling of all SST vectors,
and writes the addresses of ODT's trap
entry points into the table used by the
SVDB$ Executi ve d i recti ve.
(See Table 5-2
for a discussion of
the
SST
vector
registers and the $nV/ command.)

W or kW

Searches memory between the address limits
specified by the low memory limit register
($L) and the high memory limit register
($H) for words with bit patterns that match
those of the search argument specified
in
the search argument register
($A).
ODT
compares each memory word and the search
argument
for
equality under the mask
specified in the search mask register ($M).
Only bit positions set to 1 are compared.
When a match occurs,
ODT displays the
address of the matching location and its
contents.
If W is preceded by k, the value
k replaces the current contents of $A
before initiating the search.
If W is
preceded by m (identified by the semicolon
that follows it), the value m replaces the
current contents of $M before ODT initiates
the search.

or. miW
or. mikW

Exits from ODT and returns control to the
Executive of the host operating system.
, set:!;;,', ~t,h~"'c~Q;~~,el1~:t:;~;mo~~ :of: :~bT to

~" :mod~: (~RS~-'l:lM;';,P,'I:.US, :on lY')."

2-11

supe [vi so r

CHAPTER 3
CONTROLLING PROGRAM EXECUTION

When you run a task image into which ODT has been linked, ODT takes
control before the first
instruction of the task is executed.
Information about the task is stored in ODT's internal
registers,
as
described in Section 5.1.2.
At this point, you can execute your task immediately
commands to affect locations or registers.

3.1

issue

ODT

SETTING AND REMOVING BREAKPOINTS

A common method of using ODT is to set breakpoints at important points
in the task and then to execute the task. When a breakpoint is
reached,
execution is suspended.
You can examine locations or
re9isters to see how your task is executing.
You can then change
elements of your task and see how the changes affect execution.

3.1.1

Setting Breakpoints

To set a breakpoint at a location,
command in the following format:

issue

(for

'breakpoint')

ai nB

a
An address expression (in any of the forms described
in Section
2.2)
representing the location at which the breakpoint is to be
set.
This location must always be the first word of an
instruction.

n
The number of the breakpoint address register (from 0 to 7) to be
used to store the address of the specified location.
If you omit
n,
breakpoint address registers are assigned
sequentially,
beginning with register o.
You can also set a breakpoint by opening a breakpoint address register
as a word location and changing its contents.
The address of a
breakpoint address register is its register name,
$nB.
Opening and
changing the contents of word locations is described in Chapter 4.
Registers are described in Chapter 5.

3-1

CONTROLLING PROGRAM EXECUTION
: In;'RSX~llM-PLUS. systems where separate instr\~~'Pi;<#1::an(f:t4:~:~:i:~:~E~~i£~:;;;~~f~*~:n
:;~sed,"":QreakPoints always refer to .instructlo'n !s:paqe:i:i:.e.9;~;f~)·~~~i'~f~:thiii~;
. ¢p,acfe, .,~o .wh ieb you are referring. when .yo uset ;th.~:~~~~kp()J~~$:;;:;:,Wh~fE:'~E?
::~H~'~l1gg ing .·.s~?~ion begins, you are a ut6matic~1~¥, :a~9';$~~:i~9;·I!ns:t.tnj~:~lt~~~;;
. EJPiaC!e.i::LYoliaqcess: data space by enter ing .the "DC;Omm<ll'Qd·;.an(r':rel:;U;t;O;~£~;ti<b;ii

-:::t :::~~:M::::: b:

Ib:::::::~ a.adr~Z~~j~i~~~1~~~}iill~i~~1

r.
y ::::: : ng e : : :
:;'~,s:§?c'iate'd wftha:mode indicator; showing whether,:tb~:J:>:r~~.kp?:f~:t:~:?;~:~\J~7~,~:
';'~i,i:,:us*eror,supervisor mode;
this mode indi ca to~ ~~p~l1ds. ':or,i:;:':'t:n:~::::;m~g:~:;i
:'~I1;';:e'ff:eqt Cit ;the time. the breakpoint is set.
Y()us~,t,~':s:up:~3r;y;i:$E~r,:::~~g~::
:·b~}(:~nte,r ing 'the Zco~mand and return to user mO'de by:;;:e:r):t::.~tJi!\9:;;:~~t!~~:::~:;
::~:~;~mand.
c,.' "'" ::.'~;~~L~.~TJ~~.~~~;~'n~L:E:!:l
r

3.1.2

Removing Breakpoints

You can clear breakpoint address registers
(and
thus
remove
breakpoints) using the nB command, where n represents the number of
the register. If you omit n, all breakpoint address registers are
cleared. You can also clear a breakpoint and reset it by specifying a
new address expression for a breakpoint address register, using the
a;nB command.
The following example shows how
reset:

breakpoints

are

set,

cleared,

and

1020;B
2030;B
3040;B
-4050;B
-2032;lB
-3B
At this point, breakpoint address register 0 is set to location 1020,
breakpoint address register 1 is set to 2032, and breakpoint address
register 2 is set to 3040. Breakpoint address register 3 is clear.
Note that ODT generates a carriage return, a line
prompt immediately when you type the letter B.

feed,

and

new

You can also clear a breakpoint register by opening it as a word
location whose address is $nB and changing its contents, as described
in Chapter 4.

3.2

BEGINNING PROGRAM EXECUTION

To begin execution of your task, type the G (for 'go') command.
command has the following effects:

This

•

The task's starting address is returned to the program counter
from the aDT general register in which it was stored.

•

The task's stack and other general registers are restored.

•

The contents of each location at which a breakpoint was set
are swapped with the contents of the corresponding breakpoint
instruction register.
(These registers, described in Section
5.2, are initialized by ODT to BPT instructions.)

•

Execution of the task begins.
3-2

CONTROLLING PROGRAM EXECUTION
EXE~cution

continues until it reaches one of the following:

•

A breakpoint

•

An error of type BE, EM, FP, 10, or TR (described in

Appendix

•

The end of the program

Once the program is. executing, you cannot stop it except by aborting
p r0 9t:.Clrrl and,~.e~J:~ ~~t ~,n,9 ) 1;.• ,,:£(
;~;.~n;~l··,:t;Ssyst:eIrts·tl1clude
?~~/ .~., :r~~~~4~;1;j·~~r,~::$:?::::~~,~,~,,::·~:~.~,~;~~9~.:~':~:.~:~:~~~~~t).~d .}~ n Sec t io ns
J:h.~,.

When the task reaches a breakpoint, ODT executes the BPT instruction
that was swapped into the breakpoint location.
This instruction has
the following effects:
•

Task execution is suspended.

•

The contents of the user task general registers are stored
ODT internal registers.

•

The original contents are restored to all breakpoint locations
from the breakpoint instruction registers where they have been
stored.

•

ODT issues a message indicating that a breakpoint has been
reached.
This message has the format nB:a, where n is the
breakpoint address register number and a is the location of
the breakpoint that was stored in that register.

•

ODT issues its prompt.

While task execution is suspended, you may issue any ODT command.

3.3

CONTINUING PROGRAM EXECUTION

You can continue program execution using either the P (for "proceed")
command,
the G command, or the aG command.
Execution continues until
a breakpoint, the end of the program, or an error of the types
specified above is reached.
Use the P command to continue execution after a breakpoint. When you
type P,
the contents of the user general registers are restored, the
BPT instructions are swapped into all breakpoint locations, and task
execution resumes at the instruction following the last logical
instruction executed.
If execution stopped because of a breakpoint,
it will resume at the breakpoint location.
If execution stopped
because of an error, it will resume at the location following the
error location, not at the error location itself.
You can resume execution using the G command;
however, because the G
command does not transparently restore the breakpoint instruction, you
should not use it to resume execution after a breakpoint.
To resume execution at a specific location, use the aG command.
The
argument a
is an address expression representing the task location.
The address specified must correspond to a word location boundary,
that is, an even location. Registers are affected as described in
Section 3.2, and execution begins at the specified location.

3-3

CONTROLLING PROGRAM EXECUTION
Note that you can use only G or aG to begin execution of a task.
If
you type P when no G command has been executed, ODT responds with a
question mark and a new prompt.

3.4

USING THE BREAKPOINT PROCEED COUNT

If you set a breakpoint inside an execution loop, you may want to
suspend execution only when the loop has been executed a certain
number of times. You can specify how many times a
loop should be
executed by including a breakpoint proceed count with the P command,
in the form kP.
The loop is executed k-l times;
execution is
suspended when the breakpoint is reached for the kth time.
The kP command is associated only with the breakpoint that has most
recently occurred.
The count k is stored as an octal value in a
breakpoint proceed count register
($nG), where n is a
number
corresponding to the number of the appropriate breakpoint address
register.
You can examine the breakpoint proceed count registers, or set them
directly,
at any time following
the procedures for examining and
setting word locations described in Chapter 4.
These registers are
all initialized by ODT with the value 1.
If you change the value of a
register, the new breakpoint proceed count will be used when the
breakpoint is next encountered as a result of the P command.

3.5

STEPPING THROUGH THE PROGRAM

Another method of executing a task in stages is to use the S
(for
"step")
command.
With this command, you can execute user task
instructions one at a time or several at a timeG
The command has the format nS, where n is the number of instructions
that ODT should execute before suspending execution. The default
value of n is 1.
When n instructions have been executed, ODT suspends task execution
and prints a message of the form 8B:a, where a is the location of the
next instruction to be executed.
(The format of a
is relative by
default,
as explained in Chapter 4.) ODT then prompts for another
command.
The S command is implemented through the T-bit in the Processor Status
Word
(described in Appendix B). The T-bit is set when you issue the
command; when the nth instruction is executed, control is returned to
the user.
The following example shows ODT's response to
commands described in this chapter:

1,1052;B
-1,2052;lB
-G
OB:l,001052
p

1B:l,002052
S

8B:l,002056
S

8B:1,002062

3-4

the

program

execution

CHAPTER 4
DISPLAYING AND ALTERING THE CONTENTS OF LOCATIONS

During an COT session, you can
alter
the
contents -- either
instructions or data -- of locations in your task.
To alter the
contents of a location, you must first "open" the location.
You open a location by displaying
its contents,
using any of the
commands
described
in Sections 4.3 through 4.9.
The contents
displayed are automatically placed into the quantity ($Q) register.
COT displays a location by showing the address followed by a mode
operator
(either word mode or byte mode, depending on the size of the
location opened) and the contents of the location.
The format
in
which the location is displayed is controlled by the contents of the
format register ($F), as described in Table 5-1.
By default,
COT
displays addresses in relative form whenever it has the information
necessary to construct such an address:
the number of the relocation
register containing the bias value closest to (but less than) the
address, and the relative location of the address from that value.
When this information is not available, COT prints the address in
absolute form.
(Relative and absolute forms are described in Section
2.2.1.)
COT does not generate a carriage return or line feed after displaying
the contents of a location.
Until the location is closed, the cursor
remains on the same line, wrapping around as necessary.

4.1

ALTERING THE CONTENTS OF A LOCATION

You alter the contents of a location by typing the new contents
immediately after the displayed contents.
The new contents can be an
absolute octal value (of up to six digits) or an expression equivalent
to a 6-digit octal value, as described in Section 2.2.2.
If you enter an octal value, you may omit leading zeros.
In the following examples, the value 1234 is substituted for the value
123456 in the location represented by the address expression 2,0.
The
value 177426 (the two's complement result of the expression 16-370)
replaces the value 000000 in the location represented by the address
expression 4,10.
2,0/123456 1234
4,10/000000 16-370

4-1

DISPLAYING AND ALTERING THE CONTENTS OF LOCATIONS
After you have altered the contents of a location, you can verify the
new contents by displaying them in a variety of modes, using the
commands described in Section 4.10. These commands do not close the
location.
You can also verify the contents by closing the location
and then reopening it, so that the new contents are displayed.
Before you can alter the contents of a new location,
the currently open location.

4.2

you

must

CLOSING A LOCATION

To close a location without automatically opening another location,
enter the
(ij@
command. Thi s command has no effect on aDT when no
location is open.
The
(ij@
command generates a carriage return and a
then prompts for another command, as follows:

line

feed.

aDT

_1,200/450123 ®]

To close a location and automatically open another location, you can
use any of the following commands, described in Sections 4.4 through
4.9:
@

4.3

OPENING WORD AND BYTE LOCATIONS

aDT interprets the slash character (I) as a word mode octal operator
and the backs1ash character (\) as a byte mode octal operator. Using
these operators in aDT commands is the most direct way to open word
and byte locations.
These commands are described in the following
sections.
You can also open word and byte locations and display their contents
in ASCII, or open and display words in Radix-50.
Using these modes is
described in Section 4.10.

4.3.1

The

al and a\ Commands

To open a word location beginning at an address, type an address
expression corresponding to that address,
followed by a slash, in
response to the aDT prompt. The address must be even numbered.
aDT
opens the word location beginning at the specified address and
displays the contents of that location as a 6-digit octal number.
To open a byte location, type an address expression corresponding to
an odd- or even-numbered address, followed by a backs1ash. aDT opens
the byte location beginning at the specified address and displays the
contents of that location as a 3-digit octal number.
The following examples show the effects of the
10001012675 ®]
_1001\025 ®]

4-2

al and a\ commands:

DISPLAYING AND ALTERING THE CONTENTS OF LOCATIONS
4.3.2

The / and \ Commands

You can use the word mode and byte mode octal operators without
address arguments to reopen the location last opened.
The 1 command
opens the word location last opened and displays the word at that
location.
The \ command opens the byte last opened and displays the
contents of that byte.
(If the last location opened was a word, the
byte opened and displayed is the low-ordered byte of that word.)
When no location is open, you can also use the
command to
last-opened location, as described in Section 4.5.
A

4.3.3

open

the

mode

and

Moving Between Word and Byte Modes

The word mode and byte mode octal operators establish
byte mode, respectively.

word

Once you have opened a location using the word mode octal operator
(I), all locations subsequently opened will be octal words until the
mode is changed. Once you have opened a byte location using the byte
mode octal operator
(\), all locations subsequently opened will be
octal bytes until the mode is changed.
You can change from word to byte mode by opening a location with the
a\ command or by specifying an odd--numbered address as the value a in
the al command. Subsequent locations will be displayed as bytes until
a ,~ord location is explicitly opened using an even-numbered address as
the value a in the al command (or the a" or a% commands, described in
Section 4.10).
The following example shows a change from word mode to byte mode and
back again using an odd-numbered address in the al command.
(The
@
command, which opens the next sequential location in whatever mode is
currently in use, is described in Section 4.4.)
1001/123 321
=/321 @
001002 \021

001003 \010

001004 \201 ru
_1006/ 1020 54
If a word location is open, you can examine its low-order byte by
typing the byte mode octal operator
(\)
immediately after the
displayed contents of the location. The location is not closed and
you do not leave word mode.
The following example shows this use of
the byte mode octal operator:
_1006/102054 \054

10101012345
You can also examine words or bytes of an open location
Radix-50 modes, as described in Section 4.10.

4-3

ASCII

DISPLAYING AND ALTERING THE CONTENTS OF LOCATIONS
4.4

OPENING THE NEXT SEQUENTIAL LOCATION

To open and examine successive locations, use the
@
command.
The
@
command closes the currently open location and opens the next
sequential location.
If the currently open location is a word,
the
next sequential location will be opened as a word.
If the currently
open location is a byte, the next sequential location will be openad
as a byte.
If you specify a value before entering the
@
command,
that value
replaces the contents of the open location, as described in Section
4.1.

4.5

OPENING THE PRECEDING LOCATION

To back up in your task and open the location preceding the location
that is currently open, use the ~ command.
This command closes the
currently open location.
If the currently opened location is a word
location,
the command opens the word location immediately preceding
it.
If the currently open location is a byte, the ~ command opens the
preceding byte.
If no location is currently open, the ~ command opens and displays the
contents of the last-opened location, a word or a byte, depending on
the mode currently in effect.
If you specify a value before entering the
command,
that value
replaces the contents of the open location, as described in Section
4.1.
The following example shows the use of the
@
and
commands.
Location 232, relative to the bias contained in relocation register 0,
is opened as a word and its contents are altered.
In response to the
@
and ~ commands, ODT proceeds to the next word location and then
backs up to 232 to display the new contents.
0,232/005036 005046 @
0,000234 /012746
0,000232 /005046

4.6

OPENING ABSOLUTE LOCATIONS

To proceed from an open location to the location whose address is
contained in that location, use the @ command. This command closes
the currently open location and uses the contents of that location as
the absolute address of the next location to be opened. You can
specify new contents for the original location by entering a value
before the @ command, as described in Section 4.1.
You can only use the @ command if the currently
word.

open

location

Opening an absolute location does not necessarily mean that the
location is displayed as an absolute address.
As shown in the
following example, where relocation register 2 is set to contain the
bias value 370 (as described in Section 5.2.1), ODT still by default
displays the location as a relative address.
370;2R
2,600/012345 12746@
2,012356 /027117
4-4

DISPLAYING AND ALTERING THE CONTENTS OF LOCATIONS
Location 12356 relative to bias value
absolute address specified, 12746.

4.7

370

equivalent

the

OPENING PC-RELATIVE LOCATIONS

To open a location relative to the program counter, use the
command.
This command adds the contents of the currently open locaton to the
value of the program counter, which is the address of the currently
opened location plus 2.
ODT closes the currently open location and
opens the location whose address is the result of its calculation.
If
you enter a value before the
command, this value replaces the
contents of the open location and i~ used in the calculation.
You can only use the
word.

command if the currently

open

location

(or
if it
If the currently open location contains an odd number
contains an even number but is already a byte location), so that the
command
calculated address does not fallon a word boundary,
the
opens a byte at the location calculated.
The following examples show how the

command is used:

1000/000040
001042 /052407
0,232/012345
0,012601 /041
0,232/012345 123456
0,123712 /020301

4.8

OPENING RELATIVE BRANCH OFFSET LOCATIONS

Use the > command to open a location at a branch offset relative
the currently open location.
The offset is calculated as follows:

The low-ordered byte of the contents of the currently open
location is interpreted as a signed value.
A negative value
results in a negative branch offset.

This value is multiplied by 2.

The resulting offset is added to the PC value, which
address of the currently open location plus 2.

the

The > command closes the currently open location and opens the
location whose address is the value calculated.
Its effects are shown
in the following examples:
1,66/005046>
T,000204 /000601
1032/000407 301>
000630 /000010
If you specify a value before entering the> command,
the low-order
byte of that word
is used
in the offset calculation.
The value
replaces the contents of the open location, as described
:in Section
4.1.

4-5

DISPLAYING AND ALTERING THE CONTENTS OF LOCATIONS
4.9

RETURNING FROM A CALCULATED LOCATION

If you have used any of the three address calculation commands
described
in the last three sections (@,
,or » and wish to return
to the location from which you began to cal~ulate addresses, use the <
command.
This command closes the currently open location and reopens
the word most recently opened by a /,
@ , or ,.. command.
The following example shows the use of the

< command:

1036/021346 ,..
1034/101025 101036
102074 /000000 @ 000000 /000000 >
000002 /000102 <
001034 /101036
If the currently open location was not opened by a @,
,or> command,
the < command simply closes and reopens the current lo~ation.

4.10

USING DIFFERENT OUTPUT MODES

The examples in the previous sections have shown aDT output in word
mode octal and byte mode octal.
However, you can also use aDT to
display the contents of locations in word or byte mode ASCII and word
mode Radix-50.
These modes follow the same rules as word mode
octal:

octal

and

byte

mode

•

You can use the
@
command to open sllcceed ing loca tions in
the same mode in which the currently open Location was opened.

•

You can enter any mode operator to display the contents of the
currently open location in another mode without changing the
mode in effect or closing the location.

The interaction of mode operators was shown in Section 4.3.3, where a
location opened in word mode octal was examined in byte mode.
The
@
command that followed opened the next sequential location in word
mode octal.

4.10.1

ASCII Mode

aDT interprets the double-quote character (") as a word mode ASCII
operator and the apostrophe (') as a byte mode ASCII operator. You
open a location in word mode ASCII with the a" command and in byte
mode ASCII with the a' command.
If you open a location in any mode and then type a word mode ASCII
operator,
the contents of the open location will be displayed as two
ASCII characters but the location will not be closed.
If you open a location in any mode and then type a byte mode ASCII
operator, the contents of the low-order byte of the open location will
be displayed as one ASCII character. The locat.ion will not be closed.

4-6

DISPLAYING AND ALTERING THE CONTENTS OF LOCATIONS
The following examples show these uses of the ASCII operators:
_0,440"AB
_2,100' H
_0,232/034567 'w "w9

0,000234/000123 @]
S

If you enter the word mode ASCII operator to examine the contents of a
location
and the location is aligned on a byte boundary
(an
odd-numbered address), aDT will not return an ASCII character.
Instead,
it will display the contents of the location in the mode
currently in effect, as follows:
0,000235\025 "025

4.10.2

Radix-50 Mode

aDT interprets the percent sign (%) as a word mode Radix-50 operator.
(There is no byte mode Radix-50 operator, since Radix-50 is a method
of fitting three characters into a word and cannot be used in smaller
units.)
You can use the Radix-50 operator to open locations. The a% command
opens the location specified in the address expression a and displays
its contents as three Radix-50 characters. The % command reopens the
last-opened
word
and displays its contents as three Radix-50
characters.
If a word location is open, you can enter the % operator to examine
the Radix-50 contents of that location without closing the location.
The following examples show these
operator:

uses

the

word

mode

Radix-50

_4,232%IGI
4,232/034567 @]
=%IGI
_4,000232/034567 %IGI
Like the word mode ASCII operator, the Radix-50 operator cannot be
used to interpret values beginning on byte boundaries.
If you enter
the Radix-50 operator when the currently open location has an odd
address, aDT simply displays the byte value in the current mode.
Remember that you must enter new contents for a location as an octal
value or an expression, not as Radix-50 characters. To determine the
octal equivalent of Radix-50 characters, use the Radix-50 evaluator
(*), as described in Section 7.3.5.

4-7

CHAPTER 5
USING REGISTERS

ODT has a number of l6-bit registers.
Some of these registers are
used for
temporary storage of values;
some contain values used
repeatedly throughout the execution of your task under ODT.
All of
the registers are word locations that you can examine and alter.
Each ODT register has a unique name beginning with a dollar sign
($).
The $ and the character or characters that follow it make up an
address expression that identifies the register.
This chapter explains how ODT uses its registers.
Tables 5-1 and
summarize the registers and are useful for quick reference.

5.1

5-2

GENERAL REGISTERS

ODT has eight general registers, numbered $0 though $7, which store
the contents of the user program's general registers when ODT has
control.
These registers are automatically set when ODT first
is
invoked and when a breakpoint occurs.
They can also be set by the
user.

5.1.1

Examining and Setting General Registers

To examine a general register, enter the register name as the address
expression in the ai, a", or a% command.
For example, you can enter
any of the following:

$71
$3%
$1"
ODT opens a register like any other word location. You can then alter
the contents of the register or use any of the following commands, as
described in Chapter 4:
@

@ WI %

ODT treats the general registers as sequential word locations.

5-1

USING REGISTERS
5.1.2

Contents of General Registers

When you issue the RUN command and ODT initially gains control,
information about the user task is stored in the general register.s as
follows:
Contents

Task's entry-point address

First three characters of task's
(Radix-50)

run-time

name

Last three characters of
(Rad ix-50)

run-time

name

$3-$4

Version number of user task if the program
included the
.IDENT directive; otherwise, the
version number of ODT

task's

When a breakpoint occurs, ODT's general registers store
of the task's general registers.

5.2

the

contents

ODT INTERNAL REGISTERS

The ODT internal registers store values for
use during a debugging
session.
For example, they store the locations of breakpoints and the
memory limits to be used in search operations.
Each register is a
16-bit location that you can open by specifying the register name as
the address expression with any ODT command that opens a word
location.
You can enter any of the following:
$3R/
$A"
$C%
It is rarely useful to
Radix-50 mode.

examine

internal

ASCII

You can alter the contents of these registers as you would the
contents of any word;
however, this is not recommended in some cases,
as described in Tables 5-1 and 5-2.
Ten of the ODT internal registers are single registers;
that is,
there is only one register for each function.
You refer to one of
these registers as $x, where x is an alphabetic character.
Table 5-1
lists these registers in alphabetical order.
In the task, they appear
in the order listed in Table 2-3, that is:
$S $W $A $M $L $H $C $Q $F $X
You can access these registers as sequential word
order, as in the following example:
$8/000000

$W /000001

$A /000000

$M /177777

5-2

locations

this

USING REGISTERS
Table 5-1
COT Single Registers
Register

Function

Search argument register.
You set this
a word search argument by opening
operator, or to a byte search argument
with the \ operator.
Can also be set
memory commands described in Chapter 6.

Constant registero
The 16-bit value in
this
register can be used as an address expression or a
value through the constant register
indicator C,
described in Sections 2.2.2 and 5.3.1.

Format register. When set to zero, all user task
addresses are displayed by COT in relative form, if
an appropriate bias value is available in one of
the relocation registers.
When set to any other
value,
user task addresses are
displayed
in
absolute form.
See Section 2.2.1 for a description
of absolute and relative forms of addresses.

High memory limit register.
The location contained
in this register
is the upper location limit for
COT search,
list v and fill memory operations.
Initialized to o.

Low memory limit register.
The location contained
in this register is the lower location limit for
COT search,
list v and fill memory operations.
Initialized to o.

Search mask register.
You set this register to a
word search mask by opening with the / operator, or
to a byte search mask by opening with the \
operator.
Can also be set by arguments specified
with the memory commands described
in Chapter 6.
Initialized to minus one, 177777(octal).

Quantity register.
COT sets this register to the
last value displayed,
as described
in Section
5.3.2.
$Q is also used for
the results
of
expression calculations using the = operator.

Processor status register.
Stores the Processor
Status Word
(see Appendix B) resulting from the
last instruction executed prior to a breakpoint.
Users do not normally change the contents of this
register directly.

Directive Status Word register.
Contains
the
Directive Status Word (DSW) of the task, indicating
the success or specific cause of rejection of the
most recently executed directive.
The contents of
this register are maintained across breakpoints.
See the Executive Reference Manual of the host
system for details on the DSW.

Reentry vector register.
A positive value causes
COT
to retain register values for
successive
entries of COT, as described in Section 5.2.2.

5-3

USING REGISTERS
The other ODT internal registers are grouped into sets of eight or
three sequential word locations.
The integer n is part of the
register name, in the form $nx; you must always include n, even if
its value is o.
Table 5-2 lists the register sets alphabetically.
In the task,
they
appear as sequential word locations in the order listed in Table 2-3,
that is:
$nB $nG $nI $nR $nV $nE $nD
Table 5-2
ODT Register Sets
Register

Range of

Function

$nB

0-7

Breakpoint address register
n.
Contains
user-specified
address
of
location
(breakpoint) in the user task whose contents
are to be swapped with the contents of $nI
when a G or P command is executed.
A ninth
register,
$8B, is used by ODT for ~ing1e-step
execution.

$nD

0-2

Device control LUN
(logical unit
number)
register n.
As described in Section 6.1.4,
register $00 contains the LUN of the user
terminal and register $10 contains the LUN of
the console device. Register $20 contains the
QIO event flag number, normally a default
value of 000034 (octal).

$nE

0-2

SST stack contents register n. The top three
items on the user program stack are placed
into these registers when a synchronous system
trap occurs.
Stack contents depend on the
type of trap taken, as explained in the
Executive
reference
manual
of the host
operating system.

$nG

0-7

Breakpoint proceed count register n, where n
corresponds to breakpoint address register n.
Contains number of times
the
breakpoint
location should be encountered before the
breakpoint is recognized.
Each register is
initially set to 1 and can be set through the
kP command (see Section 3.4), or by opening
$nG
and altering its contents.
A ninth
register, $8G, is used by ODT for single-step
execution.

$nI

0-7

Breakpoint
instruction
register
n.
Initialized to contain a BPT instruction, op
code 000003, which is swapped
with
the
contents of register $nB when the G or P
command is executed. The functions of the BPT
instruction are described in Section 3.2. A
ninth register,
$81,
is used by ODT for
single-step execution.
(continued on next page)

5-4

USING REGISTERS
Table 5-2
(Cont.)
ODT Register Sets
Register

Range of

Function

$nR

0-7

Relocation
register
n.
Contains
the
relocation
bias
of a
relocatable object
module, enabling ODT to display user task
addresses in relative form, if $F is set to 0
(see Table 5-1).
ODT
initializes
each
register to 177777(octal).

$nV

0-7

SST vector register n.
Contains entry-point
address
of
ODT
routine for handling a
synchronous system trap.
If both ODT and the
user program have SST vectors enabled for the
trap, ODT automatically receives the trap,
except for vector 6
($6V), which must be
explicitly enabled through the V command
(see
Table 2-3).
ODT handling of a trap can be
disabled by clearing the register;
the user
program
vector
then
receives the trap.
Registers correspond to traps as iollows:
SST Vector

Odd address reference in word
instruction
(also,
on
some
processors,
illegal instruction
executed)

$lV

Memory protection violation

$2V

T-bit trap
executed

$3V

lOT instruction executed

$4V

Reserved or
executed

$5V

Non-IAS/RSX-ll
executed

$6V

TRAP instruction executed

$7V

PDP-ll/40
exception error

BPT

illegal
EMT

instruction

instruction
instruction

floating-point

The following sections describe the functions of ODT
internal
registers $nR,
$X,
$C, and $Q in greater detail. Registers used in
memory operations ($L, $H, $M, $A, and $nd) are described in Chapter
6.

5-5

USING REGISTERS
5.2.1

Relocation Registers

aDT's eight relocation registers allow you to refer to locations by
relative addresses instead of absolute addresses.
Since relative
addresses are easy to determine from source file listings, using them
makes debugging faster and simpler.
When aDT is initialized, each relocation register is
set
to
177777(octal).
This is the highest possible memory address and
therefore cannot be used in constructing address expressions.
To make
a
relocation register useful, you place in it the base address of a
relocatable module or another convenient point, as explained in
Section 2.2.1.
This address functions as a relocation bias that is
added to the relative address in an address expression to form the
absolute address of a location.
You obtain the base (starting) address of a module by consulting the
memory allocation synopsis in your task map. This part of the map
gives the octal starting address of each program section and each
module that makes up a program section.
It also shows the extent of
the module, in octal and decimal.
The following figure shows a memory allocation synopsis
task:
SECTION

TITLE

IDENT

for

briBf

FILE

. BLK.:(RW,I,LCL,REL,CON) 001264
001012 00522.
001264 000574 0038n. HIYA

HIYA.OBJ;l

$$RESL:(RO,I,LCL,REL,CON) 010152 000112 00074.
$$$ODT:(RW,I,GBL,REL,OVR) 002276 005654 02988.
002276 005654 02988. ODTRSX M06

ODT.OBJ;l

~.2.1.1
Setting Relocation Registers - You
can
set
relocation
registers either by opening them as word locations and altering them,
or by using special aDT commands that affect relocation registers.

To open a relocation register as an octal word, use the register name
$nR as the address expression a in the a/ command (or any of the other
commands described in Chapter 4 that open words).
You can enter a new
value for the register after examining the existing contents.
The aDT command a;nR sets register $nR to the location specified
address expression a.
If you omit n, register $OR is assumed.

5.2.1.2 Clearing Relocation Registers - To
remove
a
relocation
register from consideration in calculating addresses, enter the nR
command, where n is the number of the relocation register.
This
command sets the register to 177777 (octal), so that it is no longer
useful in constructing address expressions.
If you omit n, all
relocation registers are set to 177777(octal).

5-6

USING REGISTERS
5.2.2

The Reentry vector Register

If you have fixed a task in memory (using the FIX command, described
in the RSX-,llM/M'-PLUS MeR Operations Manual, the lAS MeR Users Guide,
and the lAS PDS User's Guide), you can use the -reentry vector
register~-$x-,--to
maintain register values set during your debugging
session and to keep track of your access to the task.
The reentry vector register contains the value -1 when your task is
built.
When you execute the task for the first time, the register
value is incremented to O. The 0 value causes ODT to omit the task
name from the invocation message line (described in Section 1.3) the
next time you enter the task. This omission indicates that the task
is fixed in memory.
If you intend to reenter the task for further debugging, you should
set $X to 1 or another positive nonzero value. As long as the value
of $X is positive and nonzero, the fixed task is reentered at the
value stored in $7
(the program counter), and the values stored in
ODT's registers are maintained. You can continue to debug the task
using the breakpoints, constants, and other values established in an
earlier debugging session.
If $X is not positive, all registers are
initialized when you reenter the task.
You can use the reentry vector register as a counter to record how
many times you have entered a fixed task.
To do this, set the
register to 1 the first time you enter your task and increment it each
time you access the task again.

5-7

CHAPTER 6
MEMORY OPERATIONS

ODT allows you to perform three
memory in your task:

kinds

operations

blocks

•

Search memory for bit patterns or references to locations

•

Fill memory with a value

•

List blocks of memory on an output device

Section 0.1 describes how you establish the registers used in memory
operations.
The subsequent sections of this chapter describe how you
use ODT commands to perform these operations.

0.1

REGISTERS USED IN MEMORY OPERATIONS

ODT memory operation commands function between limits in memory that
you must specify.
Search and fill commands require an argument to be
searched for or deposited.
Search operations also require a search
mask.
OD'r maintains registers to contain all of these values. You can set
these registers as word or byte locations (as described in Chapters 4
and 5) before issuing memory operation commands. You can also specify
a search argument and a search mask as the k and m arguments in the
commands themselves.
If you do not specify an argument in one of
these commands, ODT uses the current contents of the appropriate
register;
if you specify an argument,
that argument replaces the
contents of the register.

0.1.1

Search Limit Registers

There are two search limit registers:
$H, containing the high memory
limit for a search, fill, or list operation; and $L, containing the
low memory limit. You deposit a memory location in one of these
registers by opening it as a word location and changing its value to
the address of the location. You can specify the location in either
absolute or relative form, as follows:
$L/OOOOOO :lOOO OOJ
/ 001000 2,4060 @
_$H/OOOOOO

3,100 OOJ

6-1

MEMORY OPERATIONS
If the value in $L is greater than the value in $H, ODT will not
perform
the
memory operation requested using these registers.
Instead, ODT displays its prompt.

6.1.2

Search Mask Register

ODT initializes the search mask register $M to 177777(octal), so that
all bits are set to 1. You set the value of the register by opening
it as a word location and changing its value. Only bit positions set
to 1 in the search mask are compared in the search operation. The
value compared is that set for the corresponding bit position in the
search argument register $A.
You can also set register $M by specifying a value m, followed by
semicolon, in any of the search commands described in Section 6.2.

6.1.3

Search Argument Register

The search argument register $A contains the value searched for in a
memory search operation or filled with in a memory fill operation.
You can set this value by opening register $A as a word or byte
location and changing its contents, or by specifying the argument k in
one of the search commands described in Sections 6.2 and 6.3.
As noted in Section 6.1.2, only bit positions set to 1 in
mask are compared in any memory search operation.

6.1.4

the

Device Control LUN Registers

The device control LUN registers $00 and $10 contain the logical unit
numbers of (respectively)
the user terminal (TI:) and the console
device (CL:). You specify one of these registers as the value n in
the n:a;kL command
(described in Section 6.4.1) to indicate what
device should be used for a listing.
The Task Builder assigns default value~ for these registers:
000007
(octal) for $00 and 000010 (octal) for $10. To reset these registers,
you can link your task using the TKB option UNITS=keyword as described
in the RSX-IIM/M-PLUS Task Builder Manual or the lAS Task Builder
Reference Manual.
You may find it more convenient simply to assign a new value f~r CL:
before beginning your debugging session. Use the MCR command ASN or
the DCL command ASSIGN, in one of the following formats:
ASN devicename=CL:

(MCR command)

and
ASSIGN CL:

devicename

(DCL command)

For more information on these commands,
interpreter manual for your system.

6-2

see

the

command

line

MEMORY OPERATIONS
6.2

SEARCHING MEMORY

There are three memory search commands: W, N, and E.
Each of these
commands has several forms, depending on the number of registers that
already contain values that you want to use in the search operation.
The following sections describe these command forms.

6.2.1

Searching for a Word or Byte

The W command searches for occurrences of the search argument
(comparing bit positions specified in the search mask) within the
range set by the contents of the search limit registers.
The full form of the command is m;kW, where m specifies the search
mask and k specifies the search argument.
However, you can omit
either or both of these arguments if the corresponding registers
contain the values that you want to use.
If you omit m, you should
also omit the semicolon argument separator.
ODT performs an exclusive OR (XOR) operation on the contents of each
location and the search argument;
it then ANDs the result of this
comparison with the search mask. A result of zero indicates a match.
When a match occurs, ODT prints the address a~1 contents of the
location and repeats the search operation until the high memory limit
is reached.

6.2.2

Searching for Inequality of a Word or Byte

The N command is the opposite of the W command:
It examines the
search range for words or bytes that do not exactly match the search
argument in ~he positions determined by the search mask.
The full form of the command is m;kN, where m specifies a search mask
and k specifies a search argument. As with the W command, you can
omit either argument or both.
The search algorithm proceeds like that for the W command, except that
a location's address and contents are only displayed by ODT when the
AND operation has resulted in a nonzero value.

6.2.3

Searching for a Reference

The E command searches for memory locations containing instructions
whose execution results in a reference to the task address specified
as the search argument.
Because the search argument represents an
address, it can only be a word, not a byte.
The full form of the command is mikE, where m represents the search
mask and k the search argument. You can omit either or both of these
arguments if you want to use the values already contained in registers
$M and $A.
For effective use of the E command, the search mask should
be set to 177777(octal) , so that all bit positions are compared.

6-3

MEMORY OPERATIONS
ODT compares each location within the search limits and displays the
address and contents of locations that contain any of the following:

0.3

•

The search argument as an absolute address

•

A relative address offset reference to
specified as the search argument

the

absolute

address

•

A relative address branch reference to
specified as the search argument

the

absolute

address

FILLING MEMORY

The F command fills the block of memory defined by the high and low
memory limit registers with the value in the search argument register.
You can set this register using the command $A/
(as described
in
Section 0.1.3),
or specify the argument k with the F command, in the
form kF.
If the last location opened was a word, the memory range is filled
with words;
if the last location was a byte, the memory range is
filled with bytes.
The low-order byte in register $A is used.
In the following example, word locations 1000 through 1776 are set to
zero and byte locations 2000 through 2777 are filled with ASCII spaces
(40 octal):
1000;lR
2000;2R
3000;3R
-$L/OOOOOa
-$H/OOOOOO
OF
$L/OOIOOO
$H/001776
-$A\OOO 40

-F

0.4

1,0 ®ill
2, -2 ®ill
2,0 ®ill
3,-1 ®ill

®ill

LISTING MEMORY

The L command lists on an output device the block of memory defined by
the high and low memory limit registers.
The following sections
describe how you request a listing and what the listing looks like.

0.4.1

Command Format

The L command has the following format:
n;a;kL
n

The device control LUN register number for the listing oper~tion.
A value of 0 indicates the user terminal (TI:);
any other value
is interpreted as 1 and
indicates the console listing device
(CL:).
The default is 1.

6-4

MEMORY OPERATIONS
a
The low memory limit for the listing operation.
If you omit a,
the value of register $L is used.
If you specify a, that value
is placed in $L.
k

The high memory limit for the listing operation.
If you omit k,
the value of register $H is used.
If you specify k, that value
is placed in $H.
You must include the semicolon argument separator (;) between a and k
if you specify the argument a.
You must include two semicolons if you
specify the argument n.

6.4.2

Listing Format

A memory listing is formatted in groups of eight units.
Each line
begins with a
location,
in relative form if possible (see Section
2.2.1), followed by eight words or eight bytes in the current output
mode.
A memory listing is displayed in whatever mode was used to open
thE~ last opened location.
Thus you can list blocks of memory in word
mode octal, byte mode octal, word mode ASCII, byte mode ASCII, or word
mode Radix-50', as described in Section 4.10'.
The following example shows the output displayed on the output device
in response to various listing commands.
Note that the question mark
displayed in response to the' command is not in this case DDT's error
indicator;
it is merely the ASCII character stored in the next byte.
Example 6-1

DDT Listing Format

1344;14DDL
00'1344 /0'4750'3 0'46125 0'20'10'4 0'20'111 0'40'510' 0'42526 0'54440' 0'52517
0'0'1364 /0'20'122 0'40'5111 0'42515 0'50'0'40' 0'42514 0'5150'1 0'3750'5
1344" CO L
00'1344 "CO UL D I
HA VE Y OU
0'0'1364 "R NA ME P LE AS E?
1344\ 10'3 L
1344 \10'3 117 125 114 10'4 0'40' 111 0'40'
1354 \110' 101 126 10'5 0'40' 131 117 125
1364 \122 0'40' 116 10'1 115 10'5 040' 120'
1374 \114 105 10'1 123 10'5
1344' C L
00'1344 'c o U L D I
0'0'1354 'H A V E Y 0 U
0'0'1364 'R N A M E
P
0'0'1374 ' L E A S E
, ?
13DD;H
$H/OD14DD 0'.10'1
1344' C L
0,0'0'0'0'44 'c o U L D I
0',0'0'0'0'54 'H A V E Y o U
0',0'0'00'64 'R N A M E P
0',0'0'0'0'74 ' L E A S E ?

6-5

CHAPTER 7
PERFORMING CALCULATIONS

ODT performs a variety of arithmetic
calculations
useful
in
determining offsets, Radix-50 equivalents, and other values.
The
following sections describe commands that perform
calculations.
Section 7.1 explains how to calculate relocatable addresses. Section
7.2 explains how to calculate offsets. Section 7.3 describes how to
evaluate expressions.

7.1

CALCULATING RELOCATABLE ADDRESSES

If you know the absolute (relocated) address of a location and want to
determine what its relative address is, or what relocation register
contains the closest base address, use one of the forms of the a;nK
command.
If you specify both a, the absolute address, and n, a relocation
register,
in the a;nK command, ODT will calculate and display the
relative address, as follows:
_4000;2K =2,001460
Note that the equal sign is part of ODT's response, not
command that you enter.

part

the

If you omit n, ODT uses the relocation register whose contents
closest to (but less than) the absolute address specified.

are

If you omit a, ODT assumes the address of the last location opened.
You should omit the semicolon argument separator if you omit a.
To determine the absolute address of an open location or of the
last-opened
location, enter a dot
(current location indicator)
followed by an equal sign
(expression evaluation operator), as
described in Section 7.3.2.

7.2

CALCULATING OFFSETS

The a (for "offset") command calculates and displays the PC-relative
offset and the branch displacement from one location to another.
There are two forms of this command.
The aO command calculates the
offset from the currently open location to the location represented by
address expression a.
This form of the command can only be used when
a location is open;
you type it on the same line as the displayed
contents of the open location.

7-1

PERFORMING CALCULATIONS
The a;kO command calculates the offset from the location represented
by address expression a to the location represented by address
expression k.
(In this case, k can have any of the address expression
forms described in Section 2.2.) This command can be entered either on
the same line as an open location or on a separate line,
in response
to the ODT prompt.
The 0 command (in either form) calculates either positive or negative
offsets.
Negative offsets are displayed in two's complement formQ
ODT displays the PC-relative offset and the branch displacement as
6-digit octal numbers.
The PC-relative offset is preceded by an
underscore and followed by a space;
the branch displacement is
preceded by a right arrow (», as shown in the following example:
1034/103421 10460

000010 >000004

A location that is open when you use the aO or a;kO commands remains
open after the offset and branch displacement are displayed.
You can
perform another calculation, change the contents of the location, or
enter any ODT command that affects an open location.
Qffsets can be
.;sys'tems only).

7.3

calculated

either

:I-

EVALUATING EXPRESSIONS

You can evaluate expressions during your debugging session using the
techniques described
in the following
sections.
To evaluate an
expression while a location is open, enter the evaluation command on
the same line as the displayed contents of the location.
ODT places
the results of its evaluation into the $Q register.
To replace the
contents of the open location, you enter Q or the value of the
expression.
You can also evaluate expressions when no location is
open by typing the evaluation command in response to the ODT prompt.

7.3.1

Equal Sign Operator

To evaluate an expression, enter the expression followed by the equal
sign
(=).
The expression is converted to a 6-digit octal value,
placed in the $Q register, and displayed.
ODT truncates the octal
value of 16 bits when necessary.
Negative values are calculated, stored, and displayed
in two's
complement form.
You can specify a negative value either in two's
complement form or with the minus sign.
You can perform
evaluated.
To
the values.
To
not recognize
expressions are

addition and subtraction within an expression to be
add values, include a plus sign (+) or a space between
subtract values, include a minus sign (-).
ODT does
parentheses or assign precedence to any operator;
evaluated left to right.

An address expression, in relative or absolute form,
part of an expression to be evaluated.

can

all

You can include in the expression the constant register indicator, the
quantity register
indicator, or the current location indicator, as
described in the following sections.

7-2

PERFORMING CALCULATIONS
If you enter the equal sign without an expression to be evaluated, DDT
evaluates the null expression as zero and enters zeros in the $Q
re9ister.
The following examples show the evaluation of expressions using
equal sign.
Relocation register $OR contains the value 370.
constant re9ister contains the value 40.

the
The

0,0:= 000370
0,16=406
0, C:= 000430
-0,16+16+2=0000426
-16-370=177426
-177777+16+16=000033
-1+16+16=000033
-C 177777=000037
-232323=032323

7.3.2

Current Location Indicator

The dot indicator (.) represents the address of the currently open
location. You use this symbol to include the address of the currently
open location as part or all of an expression to be evaluated.
The following example shows how

the

current

location

indicator

uSE~d :

320:lR
=1,10/000000 .+10=000340

7.3.3

Constant Register Indicator

The C indicator specifies the l6-bit value contained in the constant
register,
SC.
You can set this register to any value and use the
indicator in place of any a or k argument in an ODT command (as shown
in Section 2.2). You change the value of C by opening the $C register
as a word location and changing its contents.

7.3.4

Quantity Register Indicator

DDT stores the last value that it displayed in the quantity register,
$Q.
When you open a location, DDT stores that location's contents in
the $Q register.
If the location is a byte, the $Q register contains
that byte in its low-order byte and zeros in its high-order byte.
You can refer to this l6-bit value by using the quantity register
indicator QD
The quantity register indicator is especially useful for
changing the contents of open locations and for setting registers, as
shown in the following examples:
1342/173214 Q+lO ®ill

~173224 ®ill

$3/013624 QiSR ®ill
=S,20/0l3644

7-3

PERFORMING CALCULATIONS
7.3.5

Radix-50 Evaluation

To enter Radix-50 characters, you must know the numeric value of each
Radix-50 word.
A Radix-50 word, as explained in section 4.10.2,
contains three Radix-50 characters.
To determine the value of the
Radix-50 word,
you enter the numeric equivalents of the Radix-50
characters in that word, separated by asterisks, as an expression to
be evaluated.
Follow the expression with an equal sign, as shown in
Section 7.3.1.
ODT calculates a 6-digit octal ~alue,
places that
value
in the $Q register, and displays it immediately after the equal
sign, as follows:
33*24*12=125752
Note that you cannot evaluate Radix-50 characters in conjunction with
any
other evaluation operation
(addition,
subtraction,
location
calculation). You cannot use any other symbol
(C,
Q,
.)
in the
expression to be evaluated.
If you specify the equivalents of only two Radix-50 characters,
fills the high byte of the word with zeros as necessary.

aDT

The Radix-50 character set includes all alphabetic and numeric
characters (A-Z, 0-9) plus three special characters: dollar sign ($),
dot (.), and space ( ) .
Table 7-1 contains the numeric equivalents of
all Radix-50 characters.
Table 7-1
Numeric Equivalents of Radix-50 Characters
Radix-50
Character
Space

A
B
C
D
E
F

G
H

I
J
K

M
N
0
P
Q
R
S

Numeric
Equivalent

Radix-50
Character

Numeric
Equivalent

T
U

24
25
26
27
30
31
32
33
34
35
36
17
40
41
42
43
44
45
46
47

1
2
3
4
5
6
7
10
11
12
11
14
15
16
17
20
21
22
23

X
Y

Z
$

Unused
0
1

2
3
4
5
6
7
8
9

The following example shows how the asterisk is used
in
with the Radix-50 operator (described in Section 4.10.2):
1054/003151 %AAA 1*3*5=003275 3275 @]
%ACE

7-4

conjunction

CHAPTER 8
ADDITIONAL DEBUGGING AIDS

ThE! Task Builder on your system allows you to specify the Jebugger of
your choice to help you in program development. You should build only
one debugger into your task at a time;
if you want to switch from one
debugger to another, you must rebuild your task.
Section 8~1 shows how you specify other debuggers to the Task Builder
for
the thre~ environments described in Chapter 1. Section 8.2
describes the Trace program, a debugging aid available on your sys~em.

8.1

ACCESSING OTHER DEBUGGING AIDS

The following sections show how to specify a debugger other than ODT
to be linked with your object module(s).
The example in each section
shows a command line for linking the Trace debugging aid, described in
Section 8.2.
You can specify the file name of any debugger in place
of [l,l]TRACE.OBJ.

8.1.1

MCR Command Line

To link a debugger with your task using MCR, specify the name of the
debugger object module as input to the Task Builder.
Follow the
debugger object module name with the IDA switch, as in the following
example:
TKB)MYTASK=MYFILE, [l,l]TRACE/DA
The IDA swit~h identifies the file specified as a debugger.
Since the
Task Builder assumes that the file type of input files is OBJ, you
need not specify the file type of the debugger object module.

8.1.2

DCL Command Line

To link a debugger into your task using DCL, specify the name of the
debugger object module as an argument to the IDEBUG qualifier with the
LINK command, as in the following example:
)LINK/DEBUG:[l,l]TRACE/TASK:MYTASK MYFILE
Since DCL assumes that the file type of input files for the linker is
OBJ, you need not specify the file type of the debugger object module.

8-1

ADDITIONAL DEBUGGING AIDS
8.1.3

lAS PDS Command Line

To link a debugger with your task using lAS PDS, specify the name of
the debugger object module as an argument to the /DEBUG switch, as in
the following example:
PDS)LINK/DEBUG: [l,l]TRACE MYFILE

8.2

THE TRACE DEBUGGING PROGRAM

The Trace program is a debugging aid that can be used
instead of or
along with ODT to provide information about the execution of a user
task.
Trace is most appropriate for use with relatively simple tasks
or with sections of tasks.
Trace is an object module that you specify to the Task Builder when
you build your task, as described in Section 8.1.
It is located in
UFD [1,1] on the system disk, with the name TRACE.OBJ.
Trace is not an interactive program like ODT. When you run your task,
Trace is executed once and prints its listing on pseudo-device CL.
To
run Trace again, you must run your task again.

8.2.1

The Trace Listing

A Trace listing contains two lines of information for each instruction
executed
in the user's task.
The first line is made up of five octal
words, representing the contents of the following registers:
1.

Current relative program counter (PC)

Current PC

Next PC

Processor Status Word

Directive Status Word

The relative PC is determined by subtracting a user-specified bias
value from the actual
PC.
Section 8.2.2 describes how you specify
this bias value.
The second line of the Trace listing contains
representing the contents of the following:
1-6.

RO through R5

Stack pointer

The top word of the stack

eight

octal

Example 8-1 is a sample Trace listing for part of a user task.

8-2

words

ADDITIONAL DEBUGGING AIDS
Example 8-1

Sample Trace Output

001714 003174 003176 170020 000001
002637 000120 000000 140200 000000

000000

001256

003074

001716 003176 003202 170024 000001
002637 000120 000000 140200 000000

000000

001256

003074

001722 003202 003074 170024 000001
002637 000120 000000 140200 000000

000000

001260

001614 003074 003100 170020 000001
002612 000120 000000 140200 000000

000000

001260

8.202

Bias Values and Ranges

You can use the GBLPAT Task Builder option to specify:
•

The bias value to be used in determining the relative PC

•

The range(s) of task locations to be traced

8.2.2.1 Specifying a Bias Value - To specify a
bias
value
for
relative PC calculation, enter an option line in the following format
in response to the Task Builder prompt:
GBLPAT=segname:.BIAS:value
segname
The name of the task's root segment.
value
The octal value to be subtracted from the actual PC to establish
relative PC.
(If a value is not specified, the initial stack
pointer is used.)

8.2.2.2 Specifying Ranges to be Traced - To specify up to four ranges
of locations for which execution should be traced, enter an option
line in the following format in response to the Task Builder prompt:
GBLPAT=segname:.RANGE:lowl:highl [ •••
segname
The name of the task's root segment.

8-3

:lown:highn]

ADDITIONAL DEBUGGING AIDS
lowl ••• lown
The low addresses, relative to the bias value, of
traced.

ranges

The high addresses, relative to the bias value, of ranges
traced.

highl ••• highn

There can be up to four ranges.
high address of each range.

You must specify both the low and the

8-4

APPENDIX A
ERROR DETECTION

ODT responds to errors in user input and to certain hardware-detected
errors that occur during task execution. This appendix describes
these errors, ODT's response to them, and suggested user action.

A.I

INPUT ERRORS

ODT uses the question mark (?) as an indicator that it has detected an
error in user
input.
After displaying the question mark,
ODT
generates a line feed and carriage return and prompts for another
command.
ODT responds with the question mark to
errors:

any

the

following

•

Reference to an address without an operator

•

Reference to an address outside the task's partition

•

Reference to a nonexistent register -- for example, $20

•

Reference to supervisor space by a nonprivileged user

•

Input of an illegal character

input

for example, 8 or 9

If you have typed an incorrect
input
string -- for
example,
contradictory arguments for the W command -- you may find that the
simplest course of action is to cancel the input string by typing an
illegal character. You cannot, however, erase a string once you have
entered the command -- the character W, in this case.
OD'l' does not tell you what error has caused it to display the question
mark.
However, an error sometimes causes ODT to return one of the
error codes listed in Section A.2, plus information on the location at
which the error occurred.
In some cases (for example, if you attempt a memory operation when $L
is greater than $H), ODT repeats its prompt but does not display a
question mark.

A-I

ERROR DETECTION
A.2

TASK IMAGE ERROR CODES

As described in Table 5-2, ODT has eight SST vector registers used to
contain pointers to error-handling routines.
If ODT detects an error
condition, it activates the appropriate routine and displays an error
message.
This message has the form cc:k, where cc is a 2-character
error code and k is the location at which the error occurred.
ODT
displays the location as a relative address if there is a relocation
register containing a base address less than the absolute address of
the location.
The following examples are error messages from a debugging session:
MP:007414
00:1,003507
The remainder of this chapter is an alphabetic list of ODT error
codes,
their meanings, and suggested user action in response to these
codes.
BE
Explanation:
Breakpoint instruction executed at
unexpected
location.
The address of the breakpoint instruction does not
match the contents of any register, SOB thr.ough $7B.
User Action:
Examine your code to determine why the unexpected
breakpoint occurred;
then continue with the P command.
EM
Explanation:
Invalid EMT instruction executed.
Only EMT 377 and
EMT 376 (for a privileged task) are allowed by the Executive for
execution of Executive Directives. Normally, vector address 30
is used for this trap sequence.
User Action:
If you want to use an EMT trap handler that you
have written, set SST vector register 5 ($5V) to the appropriate
vector address.
FP
Explanation:
Floating-point instruction error.
One of the
following has occurred: division by zero;
illegal Floating Op
Code;
flotation overflow or underflow;
conversion failure.
User Action:
Check your code for sequences that may have
one of these conditions.

caused

IL
Explanation: Reserved or illegal instruction executed.
The task
tried
to execute a nonexistent instruction, or an EIS or FPP
instruction in a system with no EIS or FPP hardware.
User Action:
Check your code for typographical errors or the use
of a nonexistent instruction.

A-2

ERROR DETECTION
IO
Explanation:
lOT instruction executed.
20 is used for this trap sequence.

Normally, vector address

User Action: To change the handling of I/O traps, set SST vector
register 3 ($3V) to the appropriate vector address.
MP
Explanation:
Memory protection violation or illegal memory
reference.
The task tried to access a location outside of the
ranges mapped, or a location which it did not have the privilege
to access.
User Action: Check your code for
typographical
errors that could lead to this condition.

programming

Explanation:
Odd address reference on word instruction. The PC
contained an odd address when trying to access a word in memory.
Also, on some processors, execution of an illegal instruction.
Users Action: Check your code for the use of a word instruction
when a byte instruction was intended (MOV instead of MOVB, for
example) or a typographical error in the address specification.
TE
Explanation: T-bit exception.
The T-bit was set by some other
mechanism than a breakpoint or an S or P command. This can occur
if bit 4 is set in a word that is interpreted as the PSW due to
its position on the stack.
User Action:

Check that the stack contains appropriate values.

TR
Explanation:
TRAP instruction executed.
address 34 is used for this trap sequence.

Normally,

vector

User Action:
To change the handling of TRAP instructions,
set
SST vector register 6 ($6V) to the appropriate vector address.

A-3

APPENDIX B
PROCESSOR STATUS WORD

The Processor Status Word (PS), stored at hardware location 777776,
contains information on the current status of the processor.
The
information contained in this location includes:
•

The current and previous operational modes
(mapped system only)

the

processor

•

The current processor priority

•

An indicator which, when set, causes a trap upon completion of
the current instruction

•

Condition codes describing the results of the last instruction
executed

The format of the Processor Status Word is shown in Figure B-1.

14 13

12 11

--.CARRY
OVERFLOW
ZERO
NEGATIVE
TRACE TRAP
GEN REG SET
PREVIOUS MODE
------.----------------------.------------------------ CURRENT MODE

ZK-491-81

Figure B-1

Format of the Processor Status Word

Bits 15 and 14 indicate the current processor mode:
user mode
(11),
supervisor mode
(01),
or kernel mode (00).
Bits 13 and 12 indicate
the previous mode, that is,
the mode the machine was in
(user,
supervisor, or kernel) prior to the last interrupt or trap.
Bits 7 through 5 show the current priority of the central processor.
The central processor operates at anyone of eight levels of priority
(0 through 7). When the central processor is operating at level 7
(the highest priority), an external device cannot interrupt it with a
request for service.
The central processor must be operating at a
lower priority than the external device's request in order for the
interrupt to take effect.

B-1

PROCESSOR STATUS WORD
The trap bit (bit 4) can be set or cleared under program control.
When set,
a processor trap will occur through location 14 upon
completion of the current user instruction, and a new Processor Status
Word will be loaded.
The trap
(T)
bit is especially useful in
debugging programs, since it provides an efficient means for
stepping
through the task one instruction at a time.
COT uses the T-bit to
execute instructions when you are stepping through your program with
the S command, described in Section 3.5.
The condition codes N, Z, V, and C (bits 3 through 0,
respectively)
indicate the result of the last central processor operation.
These
bits are set as follows:
N=l,
Z=l,
V=l,
C=l,

if the result was negative.
if the result was zero.
if the operation resulted in an arithmetic overflow.
if the operation resulted
in a carry from the
significant bit.

B-2

most

INDEX

A register, 2-6, 5-3
a symbol, 2-1 to 2-2
Abort,
task execution, 1-5
ABORT command, 1-5
Absolute u
address, 2-2
location, 2-5, 4-4
Address expression,
See Expression
Al ter ing ,
contents of location, 4-1
Argument,
register, 2-6, 5-3
separator, 2-5
Arithmetic operator,
See Operator'
ASCII,
displaying, 4-6
operator, 2-·7
Asterisk (*), 2-5
At sign command (@), 2-5, 4-4

B command, 2-8, 3-1 to 3-2
B register, 2-6, 5-4
Backslash operator (\), 2-7,
4-2 to 4-3
Bias value, 2-3, 5-6
Trace program, 8-2
Branch,
location, 2-6, 4-5
offset, 7-2
Breakpoint, 3-1 to 3-3, 5-1
address register, 2-6, 3-2,
5-4
clear, 3-2
set, 3-1
instruction y 2-7, 5-4
proceed count, 2-7, 3-3, 5-4
removing, 2-8, 3-2
set, 3-1
Byte location l,
displaying, 4-2 to 4-6
opening, 4-2 to 4-6
Byte mode,
operator,
ASCII, 2-7, 4-6
octal, 2-7, 4-2 to 4-3

C register, 2-6, 5-3, 7-3
indicator, 2-3, 2-8, 7-3

Index-l

Calculated location,
return from, 2-6, 4-6
Calculation, 7-1
offset, 7-1
relocatable,
address, 7-1
Chang i ng ,
See also Displaying
contents of location, 4-1
display mode, 4-3
Character, 2-3 to 2-4
illegal, 2-8
Circumflex command (~), 2-5,
4-4
Clear relocation register,
2-10
Closing,
location, 4-2
definition, 4-1
open location, 2-5, 4-2
Comma (,), 2-4
Command,
ODT, 2-4
at sign (@), 2-5, 4-4
B, 2-8, 3-1 to 3-2
cancel, 2-8
c i r c urn fIe x (~), 2 - 5, 4 - 4
D, 2-8
E, 2-8, 6-3
equal sign (=), 2-8, 7-2
F, 2-9, 6-4
G, 2-9, 3-2
I, 2-9
K, 2-9, 7-1
L, 2-9, 6-4
line feed, 2-5, 4-4
N, 2-10, 6-3
0, 2-10, 7-1
P, 2-10, 3-2 to 3-3
R, 2-10
relative branch location
(», 2-6
return from calculated
location «), 2-6
return key, 2-5, 4-2
S, 2-10, 3-3
U, 2-11
underscore ( ), 2-5, 4-5
V, 2-11
W, 2-11, 6-3
X, 1-4, 2-11
Z, 2-11
Constant register, 2-6, 5-3,
7-3
indicator, 7-3

INDEX

Contents of location,
See Location
CONTINUE/DEBUG command,
lAS, 1-6
Continuing,
program execution, 3-2
CTRL/C,
ODT, 1-5
CTRL/U,
ODT, 2-8
Current location,
indicator (.), 2-3, 2-5, 7-3
Cu r so r ,
ODT, 4-1

D command, 2-8
D register, 2-7, 5-4, 6-2
Data space, 7-2
command, 2-8
access, 2-8
enable, 1-3
DCL,
linking,
debugge r, 8-1
ODT, 1-3
ODTID, 1-4
supervisor libraries, 1-4
DEBUG command,
RSX-IIM-PLUS, 1-5
Debugger,
specifying to Task Builder,
8-1
Debugg i ng ,
privileged task, 1-4
session,
abort, 1-5
begin, 1-4, 3-1
end, 1-4
interrupting of, 1-5, 3-2
resuming, 1-5 to 1-6
supervisor mode, 1-4
Device control,
LUN register, 2-7, 5-4, 6-2
Directive status word,
register, 2-6,-5-3
Display,
mode, 4-1, 4-3, 4-6, 6-5
Di spl ayi ng ,
byte location, 4-2 to 4-6
location, 4-1
word location, 4-2 to 4-6
Do t (.), 2 - 5 , 7 - 3

E command, 2-8, 6-3
E register, 2-7, 5-4

Index-2

Equal si.gn (=), 2-8, 7-2
Error,
detection, A-I
input,. A-I
task image, A-2
Evaluati.ng expression,
See Expression
Examine location,
See Displaying
Exit,
ODT, 1-4
Exit command,
ODT, 2-11
Expression, 2-3
evaluating, 2-3, 7-2
format, 2-2
Radix--50, 7-4

F command, 2-9, 6-4
F register, 2-6, 5-3
Fill command, 2-9, 6-4
Fill memory, 6-4
Fixed task,
ODT, 5-7
Format,
memory listing, 6-5
register, 2-6, 5-3
Trace listing, 8-2

G command, 2-9, 3-2
G register, 2-7, 5-4
GBLPAT,
See TKB
General register, 5-2
Go command, 2-9, 3-2

H register,

2-6, 5-3

I command 11 2-9
I register, 2-7, 5-4
lAS,
linkingy
debugger, 8-2
ODT, 1-3
Indicator,
See Register indicator
Instruction space, 3-2, 7-2
command,
access, 2-9
enable, 1-3
Internal register, 5-2

INDEX

Invoking,
ODT, 1-4, 5--1

N command, 2-10, 6-3
n symbol, 2-1 to 2-2
Negative offset, 7-2
Next sequential location, 4-4

K command, 2-9, 7-1
k symbol, 2-1v 2-3

o command, 2-10, 7-1

L command, 2-9, 6-4
L register, 2-6, 5-3
Limit register, 2-6, 5-3
Line feed command, 2-5, 4-4
LINK command,
DCL, 1-3 to 1-4, 8-1
Linking,
ODT, 1-2
DCL, 1-3
MeR, 1-2
PDS, 1-3
RSX-IIM-PLUS feature, 1-3
List command, 2-9, 6-4
Li st ing ,
device,
specifying, 6-2, 6-5
format,
me~mory, 6--5
Trace program, 8-2
Locati.on,
al tering, 4-1
closing, 4-2
displaying, 4-1 to 4-3
Location indicator,
See Register indicator

M register, 2-6, 5-3
m symbol, 2-1
Mask register, 2-6, 5-3
MCR,

linking,
8-1
ODT, 1-2
ODTID, 1-3
supervisor libraries, 1-4
Memory,
fill command, 2-9, 6-4
limit register, 2-6, 5-3,
6-1
list command, 2-9, 6-4
listing format, 6-5
search, 6-3
search command, 2-8, 2-10 to
2--11
Message,
invocation, 1-4
Minus sign (-), 2-3 to 2-4
dE~bugger,

Index-3

Octal operator, 2-7, 4-2 to
4-3
ODT,
overview, 1-1
OOTID module, 1-3
Offset, 2-3, 7-1
branch, 7-2
calculation, 2-10, 7-1
negative, 7-2
PC-relative, 7-2
Opening,
absolute location, 2-5, 4-4
byte location, 4-2 to 4-6
location,
definition, 4-1
PC-relative location, 2-5,
4-5
preceding location, 2-5, 4-4
relative branch location,
2-6, 4-5
sequential location, 2-5,
4-4
word location, 4-2 to 4-6
Operating system,
return to, 2-11
Operator, 2-3 to 2-4, 2-7, 4-2
ASCII (I), 2-7
backslash (\), 2-7, 4-2 to
4-3
byte mode,
ASCI I, 2-7
octal, 2-7, 4-2 to 4-3
comma (,), 2-4
equal sign (=), 2-8, 7-2
minus sign (-), 2-3 to 2-4
plus sign (+), 2-3 to 2-4
Ra d i x - 5
%), 2 - 7
slash (I), 4-2 to 4-3
word mode,
ASCII, 2-7
octal, 2-7, 4-2 to 4-3
" (operator), 2-7, 4-6
% (operator), 2-7, 4-7
(operator), 2-7, 4-6

°(

P command, 2-10, 3-2 to 3-3
PC-relative,
location, 2-5, 4-5
offset, 2-10, 7-2

INDEX

POS,
linking,
debugger, 8-2
OOT, 1-3
Plus sign (+), 2-3 to 2-4
Preceding location,
opening, 4-4
Proceed,
command, 2-10, 3-2 to 3-3
count, 2-7, 3-3
Processor status word, B-1
register, 2-6, 5-3
Program execution,
continuing, 3-2
res urn i n g, 3 - 2
Prompt,
OOT, 1-4

Q register, 2-6, 4-1, 5-3,
7-2 to 7-3
indicator, 2-3, 2-10, 7-3
Quantity register, 2-6, 5-3,
7-3
indicator, 2-10, 7-3
Question mark (?), A-I

R command, 2-10
R register, 2-7, 5-5 to 5-6
Radix-50,
character set, 7-4
displaying, 4-6 to 4-7
evaluation, 7-4
operator (%), 2-7, 4-6 to
4-7
separator (*), 2-5, 7-4
Range,
Trace program, 8-2
Reentry,
vector register, 5-3
Reference,
search, 2-8, 6-3
Register, 2-6, 5-1
A, 2-6, 5-3, 6-2
argument, 6-2
B, 2-6, 5-4
breakpoint,
address, 2-6, 3-1 to 3-2,
5-4
instruction, 5-4
proceed count, 3-3, 5-4
C, 2-6, 5-3
constant, 2-6
0, 2-7, 5-4, 6-2
device LUN, 2-7, 5-4, 6-2

Index-4

Register (Cont.)
directive status word, 2-6,
5-3
E, 2-7" 5-4
F, 2-6, 5-3
fo rma t" 2-6
G, 2-7, 5-4
general, 5-2
H, 2-6, 5-3, 6-1
high memory limit, 2-6, 6-1
I, 2-7, 5-4
indicator, 2-8
instruction, 2-7
internal, 5-2
L, 2-6" 5-3, 6-1
low memory limit, 2-6, 6-1
M, 2-6" 5-3, 6-2
memory limit, 5-3
memory operation, 6-1
proceed count, 2-7
processor status, 2-6, 5-3
Q, 2-6, 4-1, 5-3, 7-2
quantity, 2-6, 5-3
R, 2-7, 5-5 to 5-6
reentry vector, 2-6, 5-3,
5-7
relocation, 2-7, 5-5 to 5-6
S, 2-6, 5-3
search argument, 2-6, 6-2
search limit, 5-3
search mask, 2-6, 6-2
SST stack content, 2-7, 5-4
SST vector, 2-7, 5-5
V, 2-7, 5-5
W, 2-6, 5-3
X, 2-6, 5-3,5-7
Register indicator, 2-3, 7-3
C register, 2-3
current location (.), 2-3,
2-5
Q register, 2-3
Register set, 5-4
Relative,
address, 2-2
branch location, 2-6, 4-5
Relocatable,
address, 2-2, 5-6
calculating, 2-9, 7-1
Relocation,
register, 2-2, 2-7, 5-5 to
5-6
clear, 2-10, 5-6
set, 2-10, 5-6
Reopen last location, 4-3
Resuming,
program execution, 3-2
task execution, 1-5, 3-2
Return key command, 2-5, 4-2

INDEX

S command, 2-10, 3-3
S register, 2-6, 5-3
Search,
argument register, 2-6, 5-3,
6-2
command, 6-3
limit register, 2-6, 5-3,
6-1
mask register, 2-6, 5-3, 6-2
memory, 2-8 r 2-10, 6-3
word or byte, 2-11, 6-3
Search command, 2-11
Semicolon (i) I' 2-5
Separator,
dot (.), 2-~)
Radix-50 (*), 2-5
semicolon (j:), 2-5
Slash operator (/), 2-7,
4-2 to 4-3
SST stack content,
register, 2-7, 5-4
SST vector,
handling, 2--11
register, 2-7, 5-5
Step command, 2-10, 3-3
Supervisor libraries, 1-4
Supervisor mode, 1-4, 3-2
command, 2-11
debugg ing, 1-4
install,
READ/WRITE, 1-4
set, 2-11
$ symbol, 2-6, 5-1
? symbol, A-I

TKB (Cant.)
ODT, 1-2
ODTID, 1-3
supervisor libraries, 1-4
specifying,
debugger, 8-1
UNITS option, 6-2
Trace program, 8-2
listing,
format, 8-2
Trap, 1-5 to 1-6, 2-11, 5-5,
A-2
handling, 2-11, 5-5

Task,
privileged,
debugging I 1-4
Task Builder,
See TKB
Task execution,
abort, 1-5
begin, 2-9, 3-2
continuing, 2-10, 3-2
resuming, 1-5 to 1-6, 3-2
RSX-l1M-PLUS feature, 2-9
Task name, 5-1
TE trap, 1-5 to 1-6
TKB,
GBLPAT option, 8-2
linking,

U command, 2-11
Underscore command (_), 2-5,
4-5
UNITS Task Builder option, 6-2
User mode, 1-4, 3-2
command, 2-11
set, 2-11

V command, 2-11
V register, 2-7, 5-5
Variable, 2-1
Vector register, 5-7
reentry, 2-6

W command, 2-11, 6-3
W register, 2-6, 5-3
Word location,
displaying, 4-2 to 4-6
opening, 4-2 to 4-6
Word mode,
operator,
ASCII, 2-7, 4-6
octal, 2-7, 4-2 to 4-3
Radix-50, 2-7

X command, 1-4, 2-11
X register, 2-6, 5-3, 5-7
x symbol, 2-1

Z command, 2-11

Index-5

IAS/RSX-ll
ODT Reference Manual
AA-M507A-TC
READER'S COMMENTS
NOTE: This form is for document comments only. DIGITAL will use comments submitted on this form at the
company's discretion. If you require a written reply and are eligible to receive one under Software
Performance Report (SPR) service, submit your comments on an SPR form.

Did you find this manual understandable, usable, and well-organized? Please make suggestions for improvement.

Did you find errors in this manual? If so, specify the error and the page number.

Please indicate the type of user/reader that you most nearly represent.

[J Assembly language programmer
[J Higher-level language programmer
[J Occasional programmer (experienced)
[J User with little programming experience
[J Student programmer
[J Other (please specify)

Name _ _ __

- - - -___________________________ Date ___________________________

Organization
Street
City ______

State _ _ _ _ _ _ Zip Code _ _ _ _ ___
or Country

Do Not Tear- Fold Here and Tape -

No Postage
Necessary
if Mailed in the
United States

I II

POSTAGE WILL BE PAID BY ADDRESSEE

BSSG PUBLICATIONS ZK1-3/J35
DIGITAL EQUIPMENT CORPORA.TION
110 SPIT BROOK ROAD
NASHUA, NEW HAMPSHIRE 03061

Do Not Tear - Fold Here

_. -