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DEC-XV-ULLUA-A-D

December 1975

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Document:	Linking Loader XVM Utility Manual
Order Number:	DEC-XV-ULLUA-A-D
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Pages:	52
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OCR Text

LINKING LOADER XVM
UTILITY MANUAL
DEC-XV- ULlUA-A-D

LINKING LOADER XVM
UTILITY MANUAL
DEC-XV-ULLUA-A-D

digital equipment corporation • maynard. massachusetts

First Printing, December 1975

The information in this document is subject to change without notice
and should not be construed as a commitment by Digital Equipment
Corporation. Digital Equipment Corporation assumes no responsibility
for any errors that may appear in this document.
The software described in this document is furnished under a license
and may be used or copied only in accordance with the terms of such
license.
Digital Equipment Corporation assumes no responsibility for the use or
reliability of its software on equipment that is not supplied by
DIGITAL.

1975 by Digital Equipment Corporation

The postage prepaid READER'S COMMENTS form on the last page of this
document requests the user's critical evaluation to assist us in preparing future documentation.

The following are trademarks of Digital Equipment Corporation:

DIGITAL
DEC
PDP
DECUS
UNIBUS
COMPUTER LABS
COMTEX
DDT
DECCOMM

DECsystem-10
DECtape
DIBOL
EDUSYSTEM
FLIP CHIP
FOCAL
INDAC
LAB-8

MASSBUS
OMNIBUS
OS/8
PHA
RSTS
RSX
TYPESET-8
TYPESET-IO
TYPESET-ll

CONTENTS
Page
vii

PREFACE
CHAPTER 1

1.1

GENERAL DESCRIPTION

1-1
1-1

1.2

COMMON BLOCKS

1-2

1.3

SPECIAL SYMBOLS

1-3

LOADER CODE DESCRIPTIONS

2-1

2.1

INFORMATION UNITS

2-1

2.2

PROGRAM UNIT ORGANIZATION

2-2

2.3

LIBRARY FILE ORGANIZATION

2-3

2.4

IDENTIFICATION CODES

2-3

CHAPTER 2

INTRODUCTION

OPERATING PROCEDURES

3-1

3.1

.DAT SLOT ASSIGNMENTS

3-1

3.2

CALLING THE LOADER

3-1

3.3

COMMAND STRING

3-2

3.3.1

Option Switches

3-3

3.3.2

Program Names

3-4

3.3.3

ALT MODE (Terminates Command String)

3-4

3.3.4

Command String Errors

3-4

3.4

OPERATION

3-5

3.5

ERROR CONDITIONS

3-6

APPENDIX A

PROGRAMMING NOTES

A-I

APPENDIX B

TERMS AND DEFINITIONS

B-1

APPENDIX C

SYMBOL CONCATENATION - RADIX 508 FORMAT

C-l

APPENDIX D

LOADER SYMBOL TABLE

D-l

CHAPTER 3

Index-l

INDEX
FIGURES
Number

1-1

Linking Loader I/O Functions

1-1

2-1

Information Unit Block Structure

2-1

2-2

Program Unit Organization

2-2

2-3

Block Data Subprogram Organization

2-3

2-4

Library File Organization

2-4

3-1

Linking Loader Core Map

3-7

iii

LIST OF ALL XVM MANUALS

The following is a list of all XVM manuals and their DEC numbers, including the latest version available.

Within this manual, other XVM

manuals are referenced by title only.

Refer to this list for the

DEC numbers of these referenced manuals.
BOSS XVM USER'S MANUAL

DEC-XV-OBUAA-A-D

CHAIN XVM/EXECUTE XVM UTILITY MANUAL

DEC-XV-UCHNA-A-D

DDT XVM UTILITY MANUAL

DEC-XV-UDDTA-A-D

EDIT/EDITVP/EDITVT XVM UTILITY MANUAL

DEC-XV-UETUA-A-D

8TRAN XVM UTILITY MANUAL

DEC-XV-UTRNA-A-D

FOCAL XVM LANGUAGE MANUAL

DEC-XV-LFLGA-A-D

FORTRAN IV XVM LANGUAGE MANUAL

DEC-XV-LF4MA-A-D

FORTRAN IV XVM OPERATING ENVIRONMENT MANUAL

DEC-XV-LF4EA-A-D

LINKING LOADER XVM UTILITY MANUAL

DEC-XV-ULLUA-A-D

MACll XVM ASSEMBLER LANGUAGE MANUAL

DEC-XV-LMLAA-A-D

MACRO XVM ASSEMBLER LANGUAGE MANUAL

DEC-XV-LMALA-A-D

MTDUMP XVM UTILITY MANUAL

DEC-XV-UMTUA-A-D

PATCH XVM UTILITY MANUAL

DEC-XV-UPUMA-A-D

PIP XVM UTILITY MANUAL

DEC-XV-UPPUA-A-D

SGEN XVM UTILITY MANUAL

DEC-XV-USUTA-A-D

SRCCOM XVM UTILITY MANUAL
UPDATE XVM UTILITY MANUAL
VP1SA XVM GRAPHICS SOFTWARE MANUAL

DEC-XV-USRCA-A-D
DEC-XV-UUPDA-A-D
DEC-XV-GVPAA-A-D

VT1S XVM GRAPHICS SOFTWARE MANUAL

DEC-XV-GVTAA-A-D

XVM/DOS KEYBOARD COMMAND GUIDE
XVM/DOS READER'S GUIDE AND MASTER INDEX
XVM/DOS SYSTEM MANUAL

DEC-XV-ODKBA-A-D

XVM/DOS USERS MANUAL

DEC-XV-ODMAA-A-D

XVM/DOS V1A SYSTEM INSTALLATION GUIDE

DEC-XV-ODSIA-A-D

DEC-XV-ODGIA-A-D
DEC-KV-ODSAA-A-D

XVM/RSX SYSTEM MANUAL

DEC-XV-IRSMA-A-D

XVM UNICHANNEL SOFTWARE MANUAL

DEC-XV-XUSMA-A-D

PREFACE
This manual describes the operation of the Linking Loader Utility Program as it is used in the XVr-VDOS environment.
It was assumed in the preparation of this manual that the reader is
familiar with the operation of the XVM or PDP-IS equipment and the
contents of the XVM/DOS Users Manual describing the features of the
operating system.
Chapter 2, which describes the organization of relocatable binary
program units as produced by FORTRAN IV XVM (FORTRAN AND MACRO XVM
MACRO), is relevant not only to the Linking Loader but also to CHAIN,
.SYSLD, UPDATE, and (in RSX systems) to Task Builder.
Manuals which relate to this manual are the following:
FORTRAN IV XVM Language Manual
FORTRAN IV XVM Operating Environment Manual
XVM/DOS Users Hanual
XVM/DOS System Manual
XVM/DOS Keyboard Command Guide
DDT XVM Utility Manual
UPDATE XVM Utility Manual

vii

CHAPTER 1
INTRODUCTION
1.1

GENERAL DESCRIPTION

The LOADER XVM (LOADER) is a program which operates under XVM/DOS.
The Linking Loader loads and links both relocatable and absolute 1
binary program units as output from either the FORTRAN IV Compiler or
MACRO Assembler.

These program units consist of machine language

instruction codes and special "loader codes" which tell the loader
how to load the program.
device not only

These program units can reside on the input

as separate files, but also as library files.

The

structure of the input data and description of the loader codes are
provided in Chapter 2.

Figure 1-1 illustrates the I/O functions of

the Loader.

System
Library
(. LIBR BIN)

Main and
Subprogram
Files

User
Library
( . LIBR5 BIN)

.DAT -4

.DAT -5

Console teleprinter (command input
and response)

Figure 1-1
Linking Loader I/O Functions

1A MACRO assembled program headed by a .LOC statement, e.g., .LOC
100, is an absolute binary program and the binary is output in link
loadable format. A prograre headed by an .ABS, .ABSP, .FULL, or
.FULIP statement is output as absolute block binary and cannot be
loaded by the Linking Loader.
1-1

Introduction
Initially, the Loader loads all the program units named in the command string (see Operating Procedures, Chapter 3).

The Loader then

automatically loads and links all requested I/O handlers and library
subprograms which have been implicitly requested.

The requested

library subprograms are loaded from the external (user)

library (if

one exists) and then the system library (in that order).

After both

libraries have been examined for requested subprograms, the Loader
prints the names of all subprograms which have not been found.

I/O

handlers that are already in core for the Loader's use will be
retained if required for the user's program.

The Loader also assigns

COMMON data storage areas.
There are

two modes of operation which affect how individual program

units are loaded into core memory.

When the system is running in

PAGE mode, program units cannot exceed 4080 words in size and the
loader relocates such programs so that they do not straddle a 4K
memory page boundary.

When the system is in Bank mode, program units

cannot exceed 8176 words in size and the loader relocates them to
avoid 8K memory bank boundaries.

In XVM/DOS there are on-line moni-

tor commands to select the desired mode of operation.

If a program

is written in absolute rather than relocatable binary, the loader
does not check to see if a page or bank boundary is crossed.
Optionally, symbols and their absolute definitions are loaded into a
program dictionary (symbol table)

for use by the DDT (Dynamic Debug-

ging Technique) Utility Program.

The Loader also sets up, for use

by DDT, the start execution address of the main program (in the
System Communication Table) and the initial relocation value of all
the program units (in the symbol table) .
1.2

COMMON BLOCKS

The Linking Loader permits COMMON blocks and BLOCKDATA subprograms
to overlap memory pages and banks.

When operating in either Bank

or Page Mode, the Loader allows COMMON block sizes up to 32,767 words
(32K-1).

Only non-COMMON arrays and variables are initialized to

zero by the Loader.

lImplicit subroutine requests are made by global or symbolic linkages and.are established through the use of .GLOBL pseudo-op in
MACRO and the external function references and CALL statements in
FORTRAN.
Implicit I/O handler requests are made by use of the .IODEV
pseudo-op in MACRO and the use of READ AND WRITE statements in
FORTRAN.

1-2

Introduction
If the system is running with XVM mode ON, the Loader allocates the
uninitialized COMMON blocks in core above the bootstrap.

The top of

usable core above the bootstrap is determined by the system memory
size.

If there isn't enough space above the bootstrap, the Loader

will use space below it.

If XVM mode is OFF (which is necessarily the

case in PDP-15 systems without XM15 hardware), the Loader loads
everything below the bootstrap.
MACRO programs can be linked to COMMON areas defined by FORTRAN IV
in two ways.

The recommended method is to use the .CBS and .CBD

pseudo-op in MACRO.

However, for compatibility with earlier systems,

the following is a second way.

If any unresolved globals remain after

the Loader has searched the user and system libraries and has defined
COMMON blocks, the Loader
COMMON block names.

tries to match those global names to

Wherever a match is made, the global becomes

defined as the COMMON block.

For example:

FORTRAN IV PROGRAM
INTEGER A, B, C
COMMON/NAME/c
COMMON A, B

MACRO PROGRAM
.GLOBL NAME,

.XX

I.xx IS NAME GIVEN TO BLANK COMMON
IBY THE FORTRAN COMPILER

DZM* .XX

ICLEAR A - NOTE INDIRECT REFERENCE

ISZ .XX

IBUMP COUNTER

DZM* .XX

ICLEAR B

DZM* NAME

ICLEAR C

Note that if the

values are REAL (2 words) or DOUBLE PRECISION (3

words) the MACRO

program must account for the number of words when

accessing specific variables.
1.3

SPECIAL SYMBOLS

The following symbols, when used in this manual, are defined as
follows:
Symbol

Meaning
Carriage RETURN
Horizontal Tab
Space

,[ ]

Optional Command Element

{ }

One of the enclosed command
elements must be chosen.

1-3

CHAPTER 2
LOADER CODE DESCRIPTIONS
As mentioned in Chapter 1, the relocatable and absolute binary program
units output by the FORTRAN IV Compiler and the MACRO Assembler contain both machine language instructions and loader codes.

These codes

are assigned by FORTRAN and MACRO to identify the various elements of
the binary program.

The Loader, in turn, interprets these codes to

properly relocate, link, assign COMMON areas, preserve constants, etc.
The paragraphs which follow provide descriptions of the physical organization of relocatable program units and library files and definitions
of the loader codes.
2.1

INFORMATION UNITS

The binary output from the FORTRAN compiler and the MACRO Assembler
consists of named files containing blocks of information units.

Each

information unit consists of a loader code (6 bits) and a data word
(18 bits).

The form of the object program at run time is determined

by the content and the ordering of the information units.

Several

information units may be grouped to convey a single run-time instruction to the

Loader.

Information units are grouped in blocks of four

18-bit machine words

as shown in Figure 2-1.

o
Word 1

5 6

Code 1

11 12

Code 2

Word 2

Data Word 1

Word 3

Data Word 2

Word 4

Data Word 3

17
Code 3

Figure 2-1
Information Unit Block Structure

lOPS binary

records of 48 information words and a 2-word header are

accepted by the Loader.

2-1

Loader Code Description
2.2

PROGRAM UNIT ORGANIZATION

A program unit consists of as many information units as are required
to contain the binary program.

The two basic types of program units

are diagrammed in Figures 2-2 and 2-3.

PROGRAM SIZE (code 01) does not include COMMON blocks
INTERNAL GLOBAL DEFINITIONS (code 12)
PROGRAM NAME (codes 07, 10, 23, 33)
Codes
02

Program Load Address

Instructions

Constants

Transfer Vectors

Non-COMMON variables and arrays

07
10

}

External global symbol references

14
15

symbols

}

COMMON block declarations and references

16
24
25

}

26
31
32
34,01

strings
I/O Device Routine

}

Relocation Mode
COMMON block initialization

END (code 27)

Figure 2-2
Program Unit Organization

2-2

Loader Code Description

BLOCK DATA INDICATOR (code 13 )
PROGRAM NAME (code 23)
COMMON STORAGE (codes 14, 15, and 16)
DATA INITIALIZATION CONSTANTS (codes 17, 20, 21, and 22)
END (code 27)

Figure 2-3
Block Data Subprogram Organization

2.3

LIBRARY FILE ORGANIZATION

Both system and user library files are structurally identical and are
created and maintained by the UPDATE Utility Program.

A library file

consists of a number of program units (rather than just one) in which
all end-of-file codes, except the last, have been removed.
shows the complete structure of a library file.

Figure 2-4

A library file must

not contain BLOCKDATA subprograms.
2.4

J;DENTIFICATION CODES

The identification code contained in each information unit tells the
Loader how to interpret the associated data word.
there is

As mentioned earlier

an implied order in which codes appear within a binary file.

Code

Loader Action

Program Unit or COMMON Block Size
The data word normally specifies the number of
machine words required by this program unit.

This

number does not include the required number of
machine words for COMMON storage.

The program

size is used by the Loader to determine whether or
not the program will fit within the unused locations
of any available page or bank.

This is the first

information unit of the binary output.

In absolute

loads, no checking is made to prevent overlay of
other program units; this is left to the user.

The

program size is also used to determine where to begin
loading the executable code as loading proceeds
from the bottom of the bootstrap downward in core.
If this code immediately proceeds code 34, the data
word declares the minimum size of the most recently
named COMMON block.
2-3

Loader Code Descriptions

LIBRARY FIL E

(_------------------------~A~------------------------~\
PROGRAM
UNIT

PROGRAM
UNIT

t
PR OGRAM S I Z E
DESCR IPTOR

1- - - - - -I

PPOGRAM
UNIT

PROGRAM
UNIT

ENO-OF- FILE
UNIT

PROGRAM UNIT
A

INTERNAL
I

GLOBALS
LO AD ADDRE SS
DESCRIPTOR

ONE lOPS

BIHAR Y
RE CORD

PROGRAM

-- --

lONE l OPS
BINARY
REC ORD

UNIT
DATA

VIRTUAL

}

GLOBALS

C, / C 2 /C 3

END CODE

}

"""""

INF ORMATION
UNIT

e n = 231 0 TERMINATES

TWO-WORD
HEADER

A PROGRAM UNIT. THE
NEXT UNIT MUST BE GIN
A NEW lOPS BINARY
RECORD .

C4 /C 5 /C 6

DESCRIPTOR

48 10
WORDS

06
I
I
I

C34/C35/C36

0 34
035
0 36

0-89- 17
WORD 0

005

}

WORD I l CHE CK - SU M

END -O F - FILE
UNIT

ENO ·OF- FI LE UNIT ONLY PRESENT
AT END OF LlBR FIL E.

Figure 2-4
Library File Organization

2-4

Loader Code Description

Loader Action

Data Word

L(~
02

2 3

Size

i f absolute load
i f relocatable load

Program or COMMON Block Load Address
The data word is an unrelocated memory

address.

This

address normally specifies either an absolute or a
relative storage address for program data words ana
is incremented by one for each data word
03,

04, and 05).

stor~d

(codes

If the address is relative, it is

initially incremented by the current relocation factor.
If this code directly precedes a code 34 which causes
an entrance into data initialization mode, the data
word contains a COMMON block load address which is
relative to the start of the

COMMON block.

Bit 0

of the data word is used to indicate an absolute
address (bit 0

= 1) or a relative address (bit 0

2 3

Data Word

0) .

I
I
I
load address
L(~ == relative
absolute load address
0

Load Address

Relocatable Instruction
The data word is a memory referencing instruction.

The

address portion of the instruction is incremented by
the current relocation

factor (modulo 12 bits for

page mode and 13 bits for bank mode).

The instruction

is stored in the location specified by the load
address which is incremented by one after the word
is stored.

o
Data Word

Op Code

2-5

4 5 Bank Mode
5 6 Page Mode
Unrelocated
Memory Address

Loader Code Description

Loader Action
04

Absolute Instruction/Constant/Address
The data word is either a non-memory referencing
instruction, a non-relocatable memory referencing
instruction, an absolute address, or a constant.
The word is

stored in the location specified by the

load address which is incremented by one after the
word is stored.

a
Non-Relocatable Word

Data Word

Relocatable Vector
The

data word contains a relocatable program address

(vector).

The word is incremented by the current

relocation factor.

The data word is

stored in the

location specified by the load address which is
incremented by one after the

word is

stored.

Data Word

Vector

Non-COMMON storage Allocation
The data word specifies the number of machine words
required for non-COMMON variable and array storage.
storage allocation begins at the address specified
by the load address.
by this number.

The load address is incremented

This block of memory is cleared.
4 5 Bank Mode

a
a

Data Word

5 6 Page Mode

Storage Size

Symbol - First Three Characters
The data word contains the first three chnracters
of a

symbol in radix 50

format (see Appendix C) .
S
The data word is saved by the Loader for future
reference.

2-6

Loader Code Description

Loader A_ction
0

1 2

Data Word

1
4

0
1

Symbol

to 3 character symbol
to 6 character symbol

Symbol - Last Three Characters
The data \'ford contains the last three characters of a
symbol in radix 50

format.
The data word is saved
8
by the Loader for future reference.
~his word is
used only if in the code 07 data word bit 0 = 1.

1 2

Data Word

Symbol

External Symbol Definition
The data word contains the unrelocated address of the
transfer vector for the subprogram named by the last
symbol loaded (codes 07 and 10).

If the external

subprogram has already been loaded, the address
(definition) of the symbol is stored into the specified
relocated vector address.

If the subprogram has not

been loaded and this is the initial request, the
symbol and the relocated transfer vector address are
entered into the Loader symbol dictionary as a request
for subprogram loading.

This action automatically

forces the Loader into a Library Search Mode after all
programs mentioned explicitly in the command string
have been loaded.

The Loader remains in Library

Search Mode until all unresolved globals have been
resolved.

If the subprogram has been previously

requested (symbol in the dictionary) but not loaded,
the Loader chains the

refere~ce

locations.

This chain,

generated exclusively by the Loader, is followed
when the external definition is encountered.

(Un-

chained transfer vector locations must initially contain a reference address (code 04 or 05) to themselves.)

For example,

.GLOBL SUB where SUB is vir-

tual causes the output of the following:

2-7

Loader Code Description

Loader Action

o
Data Word

2 3

SUB (radix 50 )
8

TVADD

o
°1~

2 3

___O~I____T_V_AD_D______~1

SUB is defined internally as TVADD.

Subroutine calls

are made via JMS* SUB.

2 3

Data Word

I
12

17
Transfer Vector
Address

Internal Global Symbol Definition
The data word contains the unrelocated or absolute
address (definition) of the last symbol loaded (codes
07 and 10).

The last symbol loaded is a global sym-

bol internal to the program unit which follows.

the Library Search Mode, if a request for subprogram
loading exists (code 11) in the Loader dictionary,
the relocatable

or absolute definition is stored in

the specified transfer vectors and the program unit
is loaded.

The

definition also replaces the trans-

fer vector address in the Loader dictionary.

If no

request for loading exists, the program unit is not
loaded and the Loader continues to examine information
units until

the next internal global symbol defini-

tion is found (Library Search Mode).

If the program

unit is to be loaded, all internal global symbols
following the one causing loading are automatically
entered into the Loader dictionary as defined global
symbols.

If the symbol already exists in the diction-

ary and is defined (indicating that a program unit

2-8

Loader Code Description

Loader Action
with the same name is already loaded) the Loader noes
not try to load the program unit again.

o
Data Word
13

2 3

Symbol Definition

Block Data Declaration
This information unit instructs the Loader that the
COMMON blocks and nata constants following are part of
a block data subprogram.

o
Data Word
14

2 3

Block Size

COMMON Block Definition
The data word specifies the number of storage words
required for the COMMON block named by the last symbol loaded (codes 07 and 10).

In general, the assign-

ment of memory space for the COMMON block is deferred
until all requested library subprograms have been
loaded.

The exception to this rule occurs when the

block data declaration (code 13) has been encountered.
In this case, the COMMON block name is treated as an
internal global symbol, and the block is assigned to
memory.

After the block is assigned to memory, the

starting address is entered into the Loaner dictionary, and the starting address is saved by the Loader
for future use (code 15).

All symbols in the diction-

ary associated with the block are assigned addresses
with respect to this starting address.

All symbols

which are yet to be loanen (via code 15 and 16) will
also be assigned as they are encountered.

When the

block data flag is not set, the Loaner enters the
name and the size into the dictionary (if it is not
already there)

and also enters the worn containing

the next available dictionary entry address.

This

entry will contain the first symbol in this COMMON
block and will be used as the head of the chain of all

2-9

Loader Code Description

Loader Action
symbols in this COMMON block.

The address of the

head of chain is saved by the Loader so that the new
set of symbols in the COMMON block may be added to
the chain.

The larger of the two block sizes is

retained as the block size.
When the COMMON block has already been assigned memory locations, the respective lengths are compared.
Loading terminates, with an appropriate error message,
if the assigned block is smaller.

When the assigned

block is larger or both are equal, loading continues.

o
o

Data Word
15

2 3

Block Size

COMMON Symbol Definition
The data word specifies the relative location of the
last symbol loaded (codes 07 and 10)
MON block (code 14).

in the last COM-

If the associated COMMON block

has been defined (block data), the absolute address
of the symbol is

calculated (block address plus

relative position) and placed in TV location (code 16).
When the COMMON block has not been assigned, the
relative address is entered into the Loader dictionary and chained to the symbols associated with the
COMMON block.

o
Data Word

2 3

Relative Address

COMMON Symbol Reference Definition
The data word contains the unrelocated address of the
transfer vector for references to the COMMON symbol
named by the last symbol loaded (codes 07 and 10).
The symbol definition (code 15) is stored in the relocated address specified when the associated
MON block has been assigned (code 14).

COM-

When the

block has not been assigned, the relocated address
is entered into the Loader dictionary along with the
relative address (code 15) of the symbol.

2-10

Loader Code Description

Loader Action

5 Bank Mode
6 Page Mode

o
o

Data Word
17

Address of Vector

Data Initialization Constant - First Word
The

data word contains the first machine word of a

data initialization constant.

It is saved by the

Loader for future use (code 22).

o
Data Constant

Data Word

Data Initialization Constant - Second Word
The data word contains the second machine word of a
data initialization constant.

It is saved by the

Loader for future use (code 22).

o
Data Constant

Data Word
21

Data Initialization Constant - Third Word
The data word contains the third machine word of a
data initialization constant.

It is saved by the

Loader for future use (code 22).

o
Data Constant

Data Word

Data Initialization Constant Definition
The data word contains the relative load address of
the last data initialization constant loaded (codes
17, 20, and 21) and a mode code identifying the constant (real, integer, double, logical).

The load

address is incremented by the current relocation
factor if the constant initializes a non-COMMON storage element.

When the constant initializes a COM-

MON storage element (indicated by the presence of the

2-11

Loader Code Description

Loader Action
block data flag (code 13)

the load address is incre-

mented by the address of the last COMMON block loaded
(code 14).

The constant is stored according to mode

and the relocated load address.

3
Load Address

Data Word

mode = integer
mode = real
mode = double
mode = logical

(1 word)
(2 words)

(3 words)
(1 word)

Program Name or Internal Symbol Definition
The data word contains the unrelocated or absolute
address (definition) of the last symhol loaded (codes
07 and 10).

The symbol is strictly internal to the

program being loaded and is entered conditionally (if
DDT is also loaded) along with its relocated or
lute address into the DDT symbol dictionary.
program unit name is indicated by bit

0=1

abso-

The
of the

data word.

2 3

Data Word

Symbol Definition
Internal symbol
Program name - from
FORTRAN IV or MACRO
command string

All symbols fall into this category.
24

String Code - First Half
The data word contains the unrelocated address of a
data word whose address portion is to be replaced by
another value.

The relocated address is saved by the

Loader for future use (code 25).

2-12

Loader Code Description

Loader Action

5 Bank Mode
6 Page Mode

o
o

Data Word

String Address

String Code - Second Half
The

data word contains an unrelocated address.

The

address portion of the data word specified by the first
half-string code (code 24)

is replaced with this ad-

dress (relocated modulo 12 bits (page) or 13 bits
(bank) ) .

5 Bank Mode

6 Page Mode

Data Word

Replacement Address

Input/Output Device Routine Request
The data word specifies the .DAT slot number associated
with a device level I/O routine.

The Loader defers

loading of any I/O handlers until all programs specified in the command string have been loaded.

I/O

handlers not already residing in memory (see Operating
Procedures) are loaded from the disk <lOS> area.
17

Data Word

o = single
1

2's complement
.DAT
when negative
( • IODEV ALL)
all positive .DA~
slots with non-zero
contents

End of Program Unit
This is the last information unit of a program module.
The data word contains the unrelocated or absolute
start execution address of the program.

The relocated

or absolute start address is entered into the system
communication tables to be used when control is given
to the user.

Only the first start address encountered

is entered into the communication tables.

2-13

(It

Loader Code Description

Loader Action
assumed that the first program unit specified in the
command string is the main program.)

The first add-

ress of the main program is used if the .END pseudoop did not have a start address.

Several program

units, typically a main program and several subprograms,
can be combined into a single named file in the same
manner as a library file.

The Linking Loader will

load each program unit until an end-of-file is encountered.

When loading from either the system or external

libraries, the end unit causes the Loader to examine
the next line buffer for the end-of-file (EOF) condition.

Nhen the EOF for the external library is

obtained, the Loader automatically

begins searching

the system library to resolve any remaining globals.

Data Word

(Reserved)

Enable Bank Relocation

4 5 Bank Mode
5 6 Pa9:e Mode

Start Address

This code is output by the MACRO Assembler in response
to the .EBREL pseudo-oPe

The Loader will relocate

all 03 coded data words using 13 bit addressing.

The

associated data word is unused.
32

Disable Bank Relocation
This code is output by the MACRO Assembler in response
to the .DBREL pseudo-oPe

The Loader will relocate

all 03 coded data words using 12 bit addressing.
associated data word is unused.
NOTE
Loader codes 31 and 32 do not affect the execution of the relocated code but merely the size
of the address field.
Also, these codes are
recognized only when the Loader is operating in
Page Mode. Program units which use these codes
are not allowed to overlap memory page bounds
or be larger than 4K.
These codes are intended
for use with VT15 Display programs and should
be used with caution. The instructions EBA

2-14

The

Loader Code Description

Loader Action

NOTE (Cont)
(enter bank addressing) and DBA (disable bank
addressing) should be with code relocated via
the .EBREL and .DBREL pseudo-ops.
33

Source File Extension
This code is output by the MACRO XVM Assembler.

The

data word contains the extension (in Radix 50 format)
of the source file which produced this binary.

The

extension is typically a number indicating the revision level of the program module.

It can be examined

with the Linking Loader by selection of the P option
in the loader's command string (see paragraph 3.3.1) .

o
Data Word

1 2

I Extension (Radix 50 8 )

COMMON Block Initialization
This code is output by the MACRO XVM Assembler in
response to the .CBS and .CBE pseudo-ops.

It directs

the loader to enter or leave COMMON block initialization mode, depending upon the preceding symbol (codes
07 and 10).

If the symbol is not blank, the loader

will initialize the COMMON block identified by that
symbol.

If the symbol is blank, the loader will

leave COMMON block initialization mode.
This code may be immediately preceded by code 01,
program size, when entering COMMON block initialization mode.

This is used to declare a COMMON block

size.
Code 34 must always be followed by code 02, which
denotes the COMMON block load address when entering
COMMON block initialization mode, and the program
load address when leaving COMMON block initialization
mode.

If entering COMMON block initialization mode,

the COMMON block is then initialized via codes 03,
04, and 05.

It should be noted that when in COMMON

2-15

Loader Code Description

Loader Action
block initialization mode, all relocation will be done
with respect to the base of the COMMON block.

In all

cases, the data word associated with this code (code 34)
is reserved for future use.

2-16

CHAPTER 3
OPERATING PROCEDURES
3.1

.DAT SLOT ASSIGNMENTS

Prior to calling the Loader, the user should perform all required
device and UIC assignments for both the Loader and the program to be
loaded.

Space can be saved during loading if the same version of a

device handler is used both for the Loader and for the program to be
loaded.
All programs named in the command string must reside on the device
and UIC associated with .DAT slot -4.
loaded from this device.

At least one program must be

The system library (.LIBR BIN) must be

accessible via .DAT slot -1.

If a user-created library is to be used,

it must be accessible via .DAT slot -5, and be named .LIBR5 BIN.
no user library is required,

.DAT slot -5 must be assigned to NON:

otherwise lOPS 13 (file not found) errors will occur.
3.2

CALLING THE LOADER

The Loader may be called using any of four commands, depending on the
user's requirements, as shown:

Command

Meaning

LOAD)

Load and Halt. Program execution is initiated by typing CTRL S.

GLOAD)

Load and Go. Program execution begins
automaticlly.

Load user programs along with DDT. When
loading is complete, control is given to
DDT.
Load user programs with DDT but do not
build DDT symbol table. This provides
more free core but limits debugging to
octal numbers.

1Refer to the DDT XVM Utility Program Manual for operating instructions
on DDT.

3-1

Operating Procedures

Type the desired command immediately to the right of the Monitor's $
as follows:
$LOAD)

$GLOAD)
or
$DDT)
or
$DDTNS)
When running, the Loader identifies itself with one of the following
messages, depending upon the addressing mode (Bank or Page) .
Page Mode

Bank Mode

LOADER XVM Vnxnnn

BLOADER XVH Vnxnnn
>

3.3

COMMAND STRING

The Command String must be typed immediately to the right of the
Loader's prompting symbol> in the format shown below:
>[options]+-name1 [,name2] .•. [,namen~
The option switches may be omitted as explained in Section 3.3.1.

The

left arrow (or underscore) must be present and so must at least one
program name.

The command must terminate with an @

character.

Below

are a few examples of legitimate single line command strings (the >is
printed by the Loader) :
>P +- RUN1~

>CP+-MAIN,SUBR1,SUBR2~

>+-PROD,TABLE,CONVRT~
>UL:USERA,G,SL:SYSTEM+-MAJOR,MINO~

The Loader also accepts Carriage RETURN as a substitute for comma to
separate program names.
were needed.

It would be used whenever a continuation line

For example,

>P+-PROG1,PROG2 ,PROG3 ,PROG4 ,PROGs€V
is equivalent to
>P+-PROG1 ,PROG2 ,PROG3 ,PROG4 ,PROG~

3-2

Operating Procedures
3.3.1

Option Switches

Five option switches may be selected to obtain loader map output on the
teleprinter and to specify alternate User or System Library names.

no options are selected, the default Library names apply, no map is
output, and loading time is decreased.

The switches are as follows:

P - Type program names and addresses
G - Type GLOBL symbols and addresses
C - Type BLOCK DATA names, COMMON block names and first addresses.
(.XX is the name for BLANK COMMON) and indicate programs
which initialize common blocks.
UL: ULNAME -

The User Library name is specified by ULNAME instead
of the default name .LIBRS.

SL: SLNAME -

The System Library name is specified by SLNM1E
instead of the default name .LIBR.

The option switches may be typed in any order.

The UL and SL options

must be followed by a comma (or back-arrow if last option typed).

The

P, G, and C options can optionally be followed by commas.
In typing out the memory map, the Loader first types option switch
character (p, G, or C) followed by the name or symbol and source file
extension, followed by the address.

To indicate a COMMON block initiali-

zation it types the option switch character ("C"), followed by the
COMMON block name, followed by the abbreviation "INIT".

To indicate a

BLOCK DATA program, it types the option switch character ("p"), followed
by the block data name, followed by the abbreviation "B DATA".
example:

P L...I NAME1L...1L...1023 L...I 037602

GL...I. DAL...IL...IL...IL...IL...I L...IL...IL...IO 2

76 3 2

3-3

(The program created
from source file
NAME1 023 is loaded
at 037602)
(The COMMON block
.XX (blank common)
is initialized by
the preceding program)
(The global symbol
.DA is defined to be
027632 by the following program)
(The base of COMMON
block .XX (blank
common) is 026000)

For

Operating Procedures
3.3.2

Program Names

Program names are standard six character (maximum) file names of the
programs to be loaded.
BIN extension.

The Loader assumes that all programs have a

The name of the main program (i.e., the program which

is to obtain control first after loading) must be typed first.

Alter-

natively, all programs (except BLOCKDATA subprograms) to be named in
a command string could be combined into a library file under the name
of the main

program.

The name of the main program is followed by the names of all required
subprograms which are not to be loaded from the system or user library.
Subprogram names should be typed in order of program size, largest
first and smallest last, to obtain optimum core utilization.

The pro-

gram names must be separated either by commas or by Carriage RETURNs.
If program input is from a non-directoried device, program names are
ignored and need not be typed.
RETURNs to load n programs.

Simply type n-l commas or Carriage

If program input is from a directoried

device, a null file name within the command string is ignored.

Thus

additional commas and/or Carriage RETURNs can be typed between file
names or after the final file name without affecting the semantics
of the command.
3.3.3

ALT MODE (Terminates Command String)

An ALT MODE is the only legal command string terminator for the Loader.
Once typed, program loading begins.
3.3.4

Command string Errors

Syntactical errors in command strings (e.g., omitting the back arrow
( +

cause the Loader to restart.

Typing errors which occur prior

to typing a Carriage RETURN or ALT MODE can be deleted through the
use of the RUBOUT (delete character) and CTRL U (delete line) teleprinter editing features.

The Loader can be restarted at any time

prior to typing the ALT MODE terminator by means of the CTRL P command.

On a directoried device, after the ALT MODE terminator, a

check of the

directory is made to verify the existence of each file.

If any file named is not present or no names have been specified,
the message "NAME ERROR" is output and the loader restarted to
allow the correct file names to be input.

Any other command string

errors observed after an ALT MODE has been typed are unrecoverable
and the user must return to the Monitor (via CTRL C) and reload the
Loader.

3-4

Operating Procedures
3.4

OPERATION

Upon receipt of the command string, the Loader consecutively loads all
explicitly named programs and builds a symbol table consisting of external (global) symbols, internal symbols (if DDT is to be loaded),
COMMON block definitions, and COMMON block element definitions.

Once

all named programs have been loaded, a search is begun to resolve unsatisfied subroutine requests contained in the symbol table.

The

Loader searches the lOS directory on the system disk for individual
I/O handler files.

Then a search through the user library (if present)

followed by the system library is made to load subroutines previously
referenced.

If after a pass through both libraries there remain

unresolved global symbol references, another pass is made.

This is

continued until a complete pass is made without resolving any global
symbols.

Any remaining unresolved references cause a .LOAD 3 error

and loading terminates.

Unresolved symbols are typed at the end of a

loader map (when a map is requested) and have a load address of O.
The Loader's search normally terminates as soon as all global references are resolved.

Executable program code is loaded as high in

core memory below the bootstrap as possible.

The normal progression

of loading one program module after another is downward
memory.

in core

However, because the Loader avoids placing executable code

over page and bank boundaries (if PAGE mode is ON) and just bank
boundaries (if PAGE mode is OFF), small modules may fit into holes
in higher memory which could not hold larger modules loaded first.
The first 208 locations in each page or in each bank are not loaded
as a safeguard to avoid turning indirect memory references through
words 1°8-178 of a program into auto increment register references.
COMMON blocks initialized with data 1 are allocated core below the
bootstrap at the

same time as is the executable code, but COMMON

blocks are permitted to straddle page and bank boundaries.
Once executable code has been loaded, the Loader assigns core to the
uninitialized COMMON blocks.

If the system is running with XVM mode

ON, the Loader allocates these blocks in core above the bootstrap.
The top of useable core above the bootstrap is determined by the
system memory size.
If there is insufficient space above the bootstrap,
the Loader will use space below it. If XVM mode is OFF (which is
necessarily the case of PDP-15 systems without XM15 hardware), the
Loader loads everything below the bootstrap.
When loading is complete, the Loader resets the lower free
core pointers (SC.FRL and SC.FRL+l) to indicate that the area
occupied by the Loader and its handlers, if they are not used
1COMMON blocks are initialized by BLOCK DATA subprograms in FORTRAN
and the .CBS/.CBC/.CBE pseudo-ops in MACRO.

3-5

Operating Procedures

by the loaded program, is now free core.

If XVM mode is ON, the

Loader also sets SC.FRH and SC.FRH+I to point to the lowest and
highest locations of free core in memory above the bootstrap.
free memory exists, both locations are set to -1.

If no

The Loader then

passes control either to the user's main program or to DDT in one of
several ways as follows:
a.

If the Loader was called using the LOAD command, the
Loader types t Sand waits for the user to type CTRL S
to start his program.

If GLOAD was used to call the Loader, the user's main
program is automatically started.

If either DDT or DDTNS was used to

call the Loader,

control is given to DDT (refer to the DDT XVM
Utility Manual for further information) .
In all cases, whether transferring control to the user program or to
DDT, the Loader enables XVM mode in the hardware if the XVM indicator
(see

SC.MOD)

in the Monitor is ON.

With hardware XVM mode enableo,

user program indirect memory references can be to 128K of memory
(17 bits) instead of the usual 32K (15 bits) .
3.5

ERROR CONDITIONS

The following error codes are output by both the Linking Loader and
the System Loader.

When output by the Linking Loader, the errors are

identified as shown below.

When output by the System Loader, the

errors are identified as ".SYSLD nil instead of ".LOAD nil.
Error

Explanation

.LOAD 1

Memory overflow - the Loader's symbol table
and the user's program have overlapped.
At this point the Loader memory map will
show the addresses of all programs loaded
successfully before the overflow.
Increased
use of COMMON storage may allow the program to be loaded since COMMON can overlay
the Loader and its symbol table, because
it is not initialized until run time .

. LOAD 2

Input data error - parity error, checksum
error, illegal data code, or buffer overflow
(input line bigger than Loader's buffer).

3-6

Operating Procedures

SC.FRH+l (up to 128K -1)

UPPER
FREE
CORE
Used only i ~
XVM mode is
ON

SC.FRH
UNINITIALIZED
COMMOr BLOCKS
2 4K or 32K
BOOTSTRAP
DDT (if present)

Arrows
indicate
direction
in which
search is
made for
allocatable

LOADED ~ROGRAMS,
SUBPROGRAMS,
I/O HANDLERS,
LIBRARY
SUBROUTINES &
INITIALIZED
COMMON BLOCKS
(also UNITIALIZED COMMON
BLOCKS IN
1
NON-XVM MODE)

The programs and symbol
table are build toward
one another. When preserved for use by DDT,
the symbol table resides
~n low core below free
core.

SC.FRL+l
SYMBOL TABLE

Lower free core shown
here is for the case
where the symbol table
is discarded after loading and the Loader's handlers are needed by the
user programs.

LINKING LOADER
SC.FRL
LOADER'S HANDLERS

SC.RMS

XVM/DOS
RESIDENT
MONITOR &
BUFFER POOL
I+-o

Figure 3-1
Linking Loader Core Map
1 Uninitialized COMMON blocks are loaded below the bootstrap in XVM
mode only, if there is no core available above the bootstrap.
3-7

Operating Procedures
(Cont)
Error

Explanation

.LOAD 3

Unresolved Globals - any programs or subroutines required but not found, whether
called explicitly or implicitly, are indicated in the memory map with an address of
00000.
If any of the entries in the memory map has a 00000 address, loading was
not successful: the cause of trouble should
be remedied and the procedure repeated •

• LOAD 4

Illegal .DAT slot request - the .DAT slot
requested was:
a.

Out of range of legal .DAT slot numbers:

Zero:

Unassigned: that is, was not set up at
System Generation Time or was not set
up by an ASSIGN command •

• LOAD 5

Program segment greater than 4K - the program segment being loaded in Page Mode cannot be placed in core without crossing a
Page Bound •

• LOAD 6

COMMON Block Error a.

COMMON block of zero length or larger
than 32K-l words. A loader map line
of the form:
C blknam
where:

blknam
length

length
COMMON block name
attempted length

will be output to the console Teletype l
immediately prior to the line containing the error code. The program whose
name was most recently typed out via
the "P" (program loader address) loader map option contains the offending
COMMON block reference.
b.

• LOAD 7

COMMON block requested length is greater
than its length when first loaded.
This error may be the result of loading the modules in the wrong order.
It is remedied by defining all instances
of the same COMMON block to be of identical length •

Global symbol with relocated value greater
than 32K-l. A loader map line of the form:
G Symnam
where:

value

Symnam = global symbol name
Value = attempted value

lTeletype is a registered trademark of the Teletype Corporation.
3-8

Operating Procedures

(Cont)
Explanation
will be output to the console terminal
immediately prior to the line containing the error code.
.LOAD 8

Data initialization is attempted outside
of the range of the program or COMMON
block. This can be the result of an input
error but is usually caused by an illegal
data initialization attempt via the MACRO
.CBC pseudo-op.

.LOAD 9 Device

Duplicate handler request - More than one
handler for the same device has been requested. The first two letters of the
duplicate file name are output along with
the error message. Loading continues
despite this message, but when the loader
programs are executed, interrupts initiated
by I/O requests may not properly distinguish
among the multiple handlers, causing an
error.

where device
is a two
letter code

3-9

APPENDIX A
PROGRAMMING NOTES
1.

Recommended practice for memory overflow (.LOAD 1) errors -- Apart
from the obvious techniques of segmenting large programs and linking them via CALL or .GLOBL's, use of the CHAIN and EXECUTE programs will often allow loading of programs which overflow when
using the Linking Loader.

Since CHAIN creates XCT files on stor-

age external to memory, space which would have been used by the
Linking Loader is made available to the user during the chaining
process.

Block data subprograms must be explicitly added after the main
user program; that is, the name of the block data subprogram
must be typed after that of the main program in the Loader command
string as a separate file.

Care must be taken to assign the same handler to both .DAT slots

-1 and -4 (user program input) to avoid possible incorrect linkage to one handler interrupt service when the initial I/O call
was made to another handler.
The assignment of the same handler to both the Linking Loader and
user .DAT slots prevents the unnecessary loading of extra handlers
which only take up more core.

For example, if the program being

loaded uses .DAT slots 1 and 2 for its I/O, a core-saving technique is to assign a common disk handler to .DAT slots 1, 2, -4,
-1 (and -5 if a user library .LIBR5 BIN exists).

.INIT's to negative .DAT slots -An .INIT cannot be done to .DAT slots

-4, -5, -1 and -7 since the

Linking Loader uses these slots and clears them after loading.

A-l

APPENDIX B
TERMS AND DEFINITIONS

Term

Definition

Loadable Program Unit

A main program. subprogram. or bl o ck
data subprogram.

Transfer Vector

A core location containing the address
of a subprogram or an entity in COMMON.
All references to subprograms
and entities in COMMON are indirect.

Internal Global Symbol

A symbol defined in the current pro gram
unit and accessible to all programs.

External Global Symbol

A symbol which is referenced in the c u rrent program unit and defined in another.

Unresolved Global Symbol

An external global symbol reference
which has not yet been resolved by
replacement with an internal global
symbol definition.

Relocation Factor

The amount added to relative addresses
to form absolute addresses; initially.
the first loadable core location. The
relocation factor for programs following
the first program unit is the next
available load address.
l
A method of symbol concatenation utilizing 508 characters as a "number set".
each with a unique value between and
including
to 47 8 , The symbol (number )
is converted using standard base conversion methods (see Appendix C).

Radix 508 Format

li.e., linking together.
B-1

APPENDIX C
SYMBOL CONCATENATION 1 - RADIX 508 FORMAT
Radix 508 is a technique used by the MACRO Assembler and the FORTRAN
IV Compiler to condense the binary representation of symbolic names
in symbol tables. Three characters, plus two symbol classification
bits, are contained in each 18-bit word. A symbol is defined as a
string of one to six characters; i.e.,
C C C C C C
1 2 3 4 5 6
where any of the possible six characters (C l through C6 ) can be defined as:
Character

6-bit octal code

Space
A

00
01

32
33
34
35

°~

46
47

9
#

The characters which make up a symbol are linked together in the following manner:
Word 1

« C1 *508)+C2)508+C3

Word 2

«C 4 *508)+C5)508+C6

For example, the symbol SYMNAM would be entered in the Loader's symbol table as:
2
Word 1
«23 8 *5°8)+ 31 8)5°8+ 15 8 = 475265
Word 2

« 16 8 *5°8)+1)5°8+ 15 8

053665

1i . e ., linking together.
2The sign bit of WORD1 is set to 1 to indicate that this symbol consists of more than 3 characters and that the WORD2 is necessary.

C-1

APPENDIX D
LOADER SYMBOL TABLE
COMMON BLOCK NAME

17
Block Size
Name (2A)

Symtab address of last entry in chain
Block definition

3
4

~
a
--a

D = 7 when not defined
D = 3 when defined

"Name" may require 2 words

if no entries
if not defined

COMMON NAME

I Symtab Chain Address
TV Address

____ ID 4 Address = a if
last entry in chain
+ - - - - BO = 1 for easy entry
update

Relative Address in Block

If associated COMMON block was defined when code 14 is encountered, no
entry is needed in the symbol table.
UNRESOLVED OR INTERNAL GLOBAL

a
1
I 10
2

Definition
Name (2A)

Definition (Unresolved) = Absolute Address of last TV in chain
Definition (Internal) = Absolute address of Symbol
"Name" may require 2 words.
Unresolved ID
1
Internal ID
5
INTERNAL NAMES
1 Orl-I-D--~2~1-=3-----D-e-f-i-n-i-t-i-o-n---------1~7I
2 .

Name (2A)

"Name" may require 2 words

D-1

ID=O
(If Pro-

gram Name
ID = 7)

Only entered
into the symbol table
during DDT
loads

INDEX
Absolute address, 2-6
Absolute instruction, 2-6
ALT MODE, 3-4
Array storage, 2-6
Assembler, MACRO, 2-1

FORTRAN compiler, 2-1

Global symbol references, unresolved, 3-5

Bank mode, 1-2
Binary output, 2-1
Block data declaration, 2-9
Block data subprogram organization, 2-3
BLOCKDATA subprograms, 1-2, A-l
Bootstrap, 1-3, 3-5

Handlers, A-l

Calling the loader, 3-1
Carriage RETURN, 3-2
CHAIN and EXECUTE programs, A-l
Character deletion, 3-4
Characters of a symbol, 2-6, 2-7
Command string, 3-2
errors, 3-4
terminator, 3-4
Comma used as separator, 3-2
COMMON blocks, 1-2
definition, 2-9
initialization, 2-15
size, 2-3
COMMON symbol definition, 2-10
Compiler, FORTRAN, 2-1
Constant, 2-6

.DAT slot assignments, 3-1, A-l
Data initialization constant
definition, 2-11
Data word, 2-1
DDT (Dynamic Debugging Technique)
Utility program, 1-2
Definitions, B-1
Delete character, 3-4
Delete line, 3-4
Device assignment, 3-1
Disable bank relocation, 2-14

Identification code, 2-3
Information units, 2-1
Input/output,
functions, 1-1
handlers, 1-2
Input/output device routine
request, 2-13
Instruction, relocatable, 2-5
Internal global symbol definition,
2-8
Internal symbol definition, 2-12

Library,
files, 2-3, 2-4
search, 2-7, 3-5
subprograms, 1-2
Library, system, 3-1
Line deletion, 3-4
Load address, 2-5
Loader codes, 1-1, 2-1
Loader map output, 3-3

Machine language instruction
codes, 1-1
Machine words, 2-3
MACRO assembler, 2-1
MACRO programs, 1-3
Memory map, 3-3
Memory overflow, A-l
Memory reference instruction, 2-5

Names, program, 3-4
Enable bank relocation, 2-14
End-of-file codes, 2-3
End of program unit, 2-13
Error codes, 3-6
Errors, command string, 3-4
Executable program code, 3-5
External library, 1-2
External symbol definition, 2-7

Option switches, 3-3
Output, binary, 2-1
Overflow of memory, A-l

Index-l

PAGE mode, 1-2
Program,
name, 2-12, 3-4
size, 1-2
start, 3-6
unit, 2-2, 2-3

Terms, B-1
Transfer vector, 2-7
Typing errors, 3-4

Unresolved global symbol
references, 3-5
Radix 50, 2-7, C-l
Relocatable instruction, 2-5
Relocatable vector, 2-6
Relocation factor, 2-5

Variable storage, 2-6
Vector, relocatable, 2-6

Source file extension, 2-15
Start program, 3-6
Storage allocation, 2-6
String code,
first half, 2-12
second half, 2-13
Subprograms, 1-2
Symbol, 2-6, 2-7
concatenation, C-l
table, 1-2, 0-1
Symbols used in manual, 1-3
Syntactical errors, 3-4
System library, 1-2, 3-1

Index-2

Linking Loader
XVM Utility Manual
DEC-XV-ULLUA-A-D

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