Meta-Assembler (MASM) Programming Reference Manual

Section 1
Introduction
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MASM (meta-assembler) is not limited to generating code for a particular hardware
architecture. When the MASM processor is loaded, it has the predefined OS 1100
instruction set. However, with the built-in directives and functions, you can define the
instruction set and useful directives for any hardware architecture, if the output of
MASM (OS 1100 relocatable binary or object module format) can be converted to a form
acceptable to the operating system on the alternate architecture.
Note: Unisys supports “extended mode” MASM usage (assembler directive $EXTEND
with or without assembler directive $OBJ) only in software written by Unisys
or in interfaces written by the customer that explicitly require extended mode
assembler-produced elements according to the documentation written by
Unisys. In a “nonextended mode” MASM usage (absence of assembler
directive $EXTEND), Unisys does not support the generation of object
modules (use of assembler directive $OBJ) but will continue to provide full
support for the generation of other provided element types which are not object
modules (absence of both the $EXTEND and $OBJ assembler directives).
The processor accepts both Fieldata and ASCII input and maintains character constants
in either code as specified by the user. MASM uses an internal code to store character
constants that do not have to be maintained in a specific character code, such as names
in the dictionary and some relocation information.
MASM performs specified tasks based on the interpretation of statements received
primarily using the symbolic input/output routine (SIR$); MASM then produces output
that depends on the user’s request. The relocatable output routine (ROR) produces a
relocatable binary element. The object module output routine (OMOR) produces an
object module element. MASM optionally produces a printed listing of the input and its
processed form. The structure of the input and output forms is presented in Section 2.
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