Xerox 530 User manual

Xerox Extended Symbol
Xerox530 and Sigma 2/3 Computers
.Language and Operations
. Reference Manual
90 10 52F

© 1972, Xerox Corporation
Xerox Extended Symbol
Xlerox 530 and Sigma 2/3 Computers
language and Operations
Reference Manual
90 10 52F
Apri I 1976
XEROX
File No.: 1 X23
XH36, Rev. 0
Printed in U.S.A

REVISION
This edition merely incorporates the 90 10 52E-l and 90 10 52E-2 revision packages into the manual. Changes in
the text from that of the previous manual are indicated by a vertical line in the margin of the page.
RELATED PUBLICATIONS
Title
Publ ication No.
Xerox 530 Computer/Reference Manual
90 1785
Xerox Sigma 2 Computer/Reference Manual
9009 64
Xerox Sigma 3 Computer/Reference Manual 90 15 92
Xerox Real-Time Batch Monitor (RBM)/RT, BP Reference Manual
90 10 37
Xerox Real-Time Batch Monitor (RBM)/OPS Reference Manual
90 1555
Xerox Real-Time Batch Monitor (RBM)/Userls Guide
90 1960
Xerox Symbol/LN, OPS Reference Manual
90 10 51
Manual Content Codes: BP - batch processing, LN - language, OPS - operations, RBP - remote batch processing,
RT - real-time, SM -system management, TS - time-sharing, UT - utilities.
The specifications of the software system described in this publication are subject to change without notice. The availability or performance af some features
may depend on a specific configuration of equipment such as additional tape units or larger memory. Customers should consult their Xerox sales representative
fOI details.
ii

CONTENTS
PREFACE
vi
Address LiteraIs
22
ADRL
23
1.
INTRODUCTIO N
5.
LOCATION COUNTERS AND PROGRAM
Programming Features__ SECTIONS
24
Error Detection ____
Extended Symbol Language Locati
on Counters
24
Extended Symbol Processor Setting the Location Counters
24
( ORG
24
LOC
25
2.
EXTENDED SYMBOL L/\NGUAGE BOUND
25
ELEMENTS A ND SYNTAX 3
RES
26
COMMON
26
Language Elements __
3 Program Sections
26
Characters ____
3 ASECT/CSECL
26
Symbols 3
Constants ____
4
Expressions 5
6.
EXTENDED SYMBOL DIRECTIVES
28
Litera Is _______
7
Syntax 8
DATA
28
Statements ____
8
DEF
29
Statement Continuatiion 9 DISP
29
Comment Li nes ___
9 DO/ELSE/FIN 30
Processing of Symbols __
9 END
32
Defining Symbols __ 10
EQU
33
Redefinable SymbolL
10
GEN
33
Symbol References __ 10 GOTO
34
Classification of Symbols
10
IDNT 35
Symbol Tables ___
10
LBL
35
Absolute and Relocatable Values
11
LIST
35
Symbols
11
LOCAL
36
Expres'ions
11 PAGE
37
PCC
37
REF
37
3.
XEROX 530 AND SIGMA 2/3 MACHINE
S:STEP 37
INSTRUCTIONS
13
SET
38
SOCW
38
Class 1:
Memory Refere:nce Instructions 13 SPACE
38
Single Precision Clas;s 1 Instructions
13
SREF
38
Multiple Precision Class 1 Instructions
15
TEXT
39
Field Addressing Class 1 Instructions
15
TEXTC 39
Class 2:
Conditional Br<elnch Instructions 16
TITLE
39
Class 3:
Shift Instructions
16
Class 4:
Copy Instructions
16
7.
PROCEDURES
41
Class 5:
Input/Output Control Instructions ___
17
Procedure Format
41
CNAME
41
4.
ADDRESSING
18
PROC
41
PEND
42
Argument Addressi ng Format
18
Procedure References
42
Direct Addressing--
19
Procedure-LocaI Symbol Reg ions
42
Indirect Addressing __
19
Intrinsic Functions
43
BASE ____
19
ABS
43
Symbolic-Relative Addressing 19
AF
44
Automatic Addressing
__
20 AFA
44
Address Generation Dia9nostics 20 AFNUM
45
Literal Pools ____
21 AFR
45
LPOOL
21
AT
45
iii

CF
46 D.
CONCORDANCE PROGRAM
74
CFNUM
46
CFR
47
Introduction
74
UFV
47
Concordance Listing
74
Sample Procedures 48
Local Section
74
Nonlocal Section
74
Proc Section
74
8.
OPERATIONS
50 Opcode Section
74
Concordance Control Command
75
RBM Control Commands
50
Section Control Commands
75
JOB Control Command
50
Error Alarms
75
ASSIGN Control Command 50 Compatibility
76
DEFINE and TEMP Control
Cards
(Temporary Fi Ie Definition) 51
XSYMBOL Control Command 51
E.
EXPANSION OF SIGMA 3 SIMULATED
BA 51 INSTRUCTIONS
77
BO
52
CR
52 No Indirect Addressing 77
DW
52 Indirect Addressing
77
GO
52
LO
52
LU
52
NP
52
PP
52
FIGURES
SL
52
SO
52
l.
Extended Symbol Character Set
3
SS
52
UI
53
2 •.
Xerox Sigma Symbolic Coding Form 8
Updating a Source Program 53
Standard Object Program Format 57 3. Flowchart of DO/ELSE/FIN Loop 31
Object Module Records 57
Load Items 57
4. Deck Setup for Assembling Multiple
Assembler Diagnostics
57 Programs Using the BA Option
54
F1ags
57
Error Messages
58 5. Deck Setup for Assembl ing Multiple
Assembly Listing
63 Programs Without BA Option
54
Summary Tables 63
6. Deck Setup for Using the UI Option With
INDEX
79
the BA Option
55
7.
Deck Setup for Using the UI Option Without
the BA Option
56
APPENDIXES
8. Sample Update Listing With Errors
58
A.
SUMMARY OF XEROX 530 AND SIGMA 2/3
9.
Assembly Listing Format
64
INSTRUCTIONS
67
10.
Assembly Listing
64
Memory Reference Instructions (C lass 1)
67
Basic Set
67
D-l.
Sample Concordance Deck Setup
76
General Register Set
67
Floating-Point Set
67
D-2.
Concordance From Xl RAD
File
Multiple Precision Set
67
Following an Assembly
76
Field Addressing Set
68
Conditional Branch Instructions (Class 2)
68
Shift Instructions (Class 3)
68
Copy Instructions (C lass 4)
68
Input/Output Instructions (Class 5)
68
TABLES
B. EXTENDED SYMBOL DIRECTIVES
69
l. Extended Symbol Operators
6
C. INCOMPATIBILITIES BETWEEN EXTEN DED
SYMBOL AND SYMBOL
73
2. Error Messages
59
iv

EJCAMPLES
21.
GEN2 Directive
34
22.
GOTO Directive
35
l.
Statement Continuaf'ion 9
23. LOCAL Directive
36
2.
Expressions Using +and - Operators 12
24. LOCAL Directive 36
3.
Expressions Using Miscellaneous Operators __
12 25. LOCAL Directive 36
4.
Automatic Addressing 21 26. REF Directive 37
5.
LPOOL Directive __
21
27.
SET Directive
38
6.
ADRL Directive __
23
28. TEXT Directive 39
7. ADRL Directive 23
29.
TEXTC Directive 39
8.
ORG Directive __
25
30.
TITLE Directive
40
9.
LOC Directive ___
25
31. Procedure Definition/Procedure Reference 42
lO.
BOUND Directive __
25 32. Procedure-Loca I Symbol Regions 43
1l.
RES Directive ___
26 33.
ABS Function
44
12.
ASECT and CSECT Directive
27 34. AF/AFA Function
44
13.
DATA Directive __
29 35. AFNUM Function 45
14.
DEF Directive ___
29 36. AT Function
46
15.
DO/FIN Directives.
30
37. CFNUM Function
46
16.
DO/ELSE/FIN Directives
32
38. CFR Function
47
17. DO/FIN Directives _ 32
39.
UFV Function
47
18. END
Directive ___
32 40.
AT and UFV Functions
48
19.
GEN Directive ___
34
41. Conditional Code Generation
48
20.
GEN1 Directive __
34
42. Procedure that References a Procedure 48
v

vi
PREFACE
This manual describes the Xerox Extended Symbol assembly system for the Xerox 530 and Sigma 2/3 computers. It
defines a symbolic programming language and the general operations of the processor under control of the Real-Time
Batch Monitor.
It is intended for use as a reference document by experienced programmers and does not aim to be a programming
primer. It is assumed that the reader is familiar with the basic elements of digital computer programming and with
the description of the Xerox 530 or Sigma 2/3 computers as given in the appropriate computer reference manual.

1. INTRODUCTION
Extended Symbol, the extended assembly system for
Xerox 530 and Sigma 2/3 computers, is both a programming
language and a language processor. The Extended Symbo I
processor accepts as input a source program coded in either
Symbol or Extended Symbol, processes it, and outputs an
object module, diagnostic messages, and an assembly list-,
ing. The objed language format is described in the RBM/
RT, BP Reference Manual, 90 10 37; the diagnostic mes-
sages and the format of the assembly listing are described
in Chapter 8 of this manual.
PROGRAMMING FEATURES
Extended Symbol provides the programmer with a number of
convenient features:
• Forward references, literals, and external definitions
and references simplify the task of referring to other
program elements.
• Local and nonlocal symbols can be specified and used,
• Self-defining constants focilitate use of hexadecimal
and decimal values and character strings.
• Expressions consisting of terms and arithmetic and log-
ical operators may be used as arguments in machine in··
structions and directives.
• Automatic oddressing is invoked by the assembler when
an address value is encountered that is outside the
range allowed for the stat'ement.
• ASECT and CSECT directives allow the partitioning of
a program into absolute and relocatable sections.
• The GOTO directive allows the assembler to condition-
a Ily a I ter the sequence in Vlh i ch statements a re assernbI ed.
• TEXT and TEXTC directivl~s simplify the coding of out-
put messages.
• User,-defined procedures allow the programmer to gen-
erate different sequences of code as determ ined by
conditions existing at ossembly time.
• The GEN directives provide the facility for generating
Class 1 and Class 2 machine instructions.
•
"Common" space may be shared with FORTRAN or other
Extended Symbol subprogrclms.
ERROR DETECTION
During assembly a source progrclm is checked for errors in usage
and syntax. If an error is found, appropriate noti fi cation is
given and the asse mbl yoperation conti nues so that all errors
may be 10c:Jted at one time. An assembly is terminated pre-
maturely (aborted) only if an irrecoverable I/O failure oc-
curs, or one of the assembler tables is exceeded.
EXTENDED SYMBOL LANGUAGE
The Extended Symbol language is comprised of a set of com-
mands and the qualifying rules for constructing program
statements in symbolic terms. There are two classes of com-
mands: mnemonic representations of the machine instruc-
tions and assembler (processor) directives.
A directive is a command to "he assernbler that allows the
programmer to describe or select assembly options at cssem-
bly time and, also, allows him to specify such elements in
his program as groups of data, choracter strings, and storage
areos, The format for coding program statements and the
rules of statement structure are described in thn following
chapters.
EXTENDED SYMBOL PROCESSOR
The Extended Symbol processor is a Xerox 530and Sigma 2/3
machine language program that operates as a three-pass pro-
gram assembler under control of the Real- Time Batch Moni-
tor. These posses are called the encoder, definition, and
generation passes. Throughout this manual the processor is
referred to as Extended Symbol or "the assembler".
During the encoder pass, the assembler checks the syntax of
each source statement, generates the assembler IS symbol
lable and converts constants to binnry. No semantic pro-
cessing nor symbol definition occurs during the encoder pass.
During the definition pass, the assembler a Ilocates space,
defines syrnbols, sets up symbol and literal tables as required,
and in general satisfies the many interconnection conditions
prescribed by the source program.
In the generation poss, Extended Symbol satisfies forward
and literal references and produces an object program, diag-
nostic messages, and on as~E:mbly listing.
External references (references to locations in ot!-.er programs)
and hrword referenc:es to procedure local srmbolscannot be
completely processed by the assembler; however, during the
generotion pas" information is generated in the object pro-
grom so thot the program loader may satisfy these references
prior to program execution.
In operation, the 'J"sernbler maintoins a series of temporary
storage areas:
1. Buffer areas for input of program statements and output
of object code and an assembl>.: listing.
2. Local and nonlocol symbol tables in which statements
and data identifiers {along with their storage assignments
Introduction

and perti nent characteristics) are placed as they are
defined or referenced. Local and nonlocal symbols
are
explained in Chapter 2.
3. Literal tables in which literal references are accumu-
lated until the end of assembly.
4. Three location counters: a load location counter, an
execution location counter, and a common location
counter thot provide information for the object pro-
gram -and consequently for the loader. The execution
location counter is used by the assembler in defining
symbols. The load location counter is used for linking
externa I symbol references.
The common
location counter is affected only by the
COMMON directive. Common symbols may be
2 Extended Symbol Processor
referenced as reI ocotabl e operands; however, the as-
sembler will not generate any instructions or data to
be stored in the common area.
5. Work areas used during assembly.
6. Assembly
variables and flogs in accordance with
directives.
7. Procedure definitions that are processed only when
they are referenced.
Supplied with the assembler are a set of standard procedures
which define the Xerox 530 and Sigma 2/3 machine opera-
tion codes.

2. EXTENDED SYMBOL LANGUAGE ELEMENTS AND SYNTAX
LANGUAGE ELEMENTS
Input to the assembler consists of a sequence of characters
that are combined to form assembly language elements. These
language elements, which include symbols, constants, ex-
pressions, and literals, comprise pmgram statements which
in turn comprise a source program.
CHARACTERS
The Extended Symbol character set is shown in Figure 1.
Alphabetic: A through Z, and $f!-Z" #, L-J (break char-
acter pri nts as 01 underscore")
Numeric:
Special
Characters:
(: is reserved alphClbetic character)
o through 9
Blank
+ Add (or positi ve va I ue)
Subtract (or negative value)
*
/
&
I
II
Multiply, indirect addressing prefix,
source regish::r inversion designator,
or comments line indi cator
Divide
Decimal point
Comma
Left parenthesi s
Right
parenthesis
Constant del imiter (single quotation
mark)
Logical AND
Logical OR (vertical slash)
Logical exclllsiveOR (vertical slashes)
-, Logical NOT or complement
<
> Less
than
Greater than
EquaI or introduces a litera I
<= Less than or equal
>:=; Greater than or equal
Continuation code
**
Binary shift
TAB Equivalent to blank; used to tabulate
keyboard printer output
Figure 1. Extended Symbol Character Set
The colon (:) is an a Iphabetic character reserved for use by
standard Xerox software. It is included in the names of
Moni tor routines (M :POP) and various mathematica I sub-
routines (L:ATAN) to avoid any potential conflict with user
symbols.
SYMBOLS
Characters are combi ned to form symbols. Symbols provide
programmers wi th a conveni ent method of i denti fyi ng pro-
gram elements so they can be referred to by other elements.
Symbols must conform to the followi ng rules:
1. Symbols should consist of 1 to 8 alphanumeric charac-
ters: A-Z, $, Jl~, #, :, L-J, 0-9, of which at least one
must be alphabetic. No special characters or blanks
may appear in a symbol. Only the first eight charac-
ters will be used by the assembler to identify the pro-
gram element represented by the symbol. Anyremaining
characters are ignored in processing the symbol and (if
requested) a warning error is output on the listing.
2. The characters $ and $$ may be used in the argument
field of a statement to represent the current value of
the execution and load location counters, respectively
(see Chapter 5); these characters must not be used as
symbols in the label field (see "Syntax" later in this
chapter).
The following symbols are valid:
ARRAY
R1
INTRATE
BASE
7TEMP
#CHAR
$PAYROLL
$ (execution location counter)
The following symbols are also valid, but only the llnder-
I ined portion is considered by the assembler and (if requested)
a warning error is noted.
~A TE01)NCREASE
Q!JJE~IV ~LUE
ABINVERSE
-----
The following symbols are invalid:
BASE PAY Blanks
may not appear in symbols.
Special characters (~-::) are not permitted
in symbols.
Extended Symbol Language Elements and Syntax 3