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F1le No. S360(Mod.20}-2l
Form GC24-9002-S DPS
TPS
Systems Reference Library
IBM System/360 Model 20
Disk and Tape Programming Systems
Assembler Language
rhis publication pr~vi~es the information enabling the
programmer to ~rite prograns in the IBM System/360
Model 20 OP5/rp5 Assembler language and the macr~
language.
The ~o~el 20 Assembler language allo~s the use ~of
mnemonic operation codes and symbolic representations
of storage addresses and other values. A pro~ra~ i3
written in symbolic language; This program is pro-
cesse~ by the DPS/rps ~ssenbler pr~gr3m, which rea3s
the symbolic statements and produces a program in
machine language.
By means of the macro language, the programner can
re~uce considerably the amount of repetitive co3ing
require3 for routines used frequently within a given
program or in many different programs. rhe progra~ner
must co~e the routine ~nly once an~ inclu3e it in the
macro library. He ~rites a macro instruction at the
point in the source pr~gran ~here the routine is
require~. During assembly, the Assembler reads the
macro instruction, extracts the routine from the
library, and inserts it in the object progra~. rhe
programmer can cause the ~ssenbler to tailor the rou-
tine to fit the particular problem program by specify-
ing the appropriate symb~lic operan3s in the macro
instruction.
rhe rea3er of this publication should be familiar
with basi= programming concepts and ~ith the operating
principles of his system as 3escribe3 in the appropri-
ate SRL publicati~ns. F~r a list of pertinent publi=a-
tions see ~~~_~Y2