Using z/OS Assembler

Objectives
On successful completion of this course, attendees will be able to:

• describe the format of machine instructions
• demonstrate an understanding of addressing and base registers
• explain how control sections and dummy sections are used
• describe how to use a working set of machine instructions
• explain the difference between machine and Assembler instructions
• define constants and storage
• code instructions which will perform: arithmetic, data manipulation, program control, file handling and table handling
• explain how condition codes and masks are used
• read dumps
• explain how module linkage works
• use BASSM and BSM instructions
• understand the concepts of 31 & 64 bit addressing and its effects on existing machine instructions.

Who Should Attend
Programmers and systems programmers who will need to 'read, mend and modify' Assembler programs.
Prerequisites
Experience of using MVS, including using TSO/ISPF and submitting batch jobs. For programmers it is an advantage to have a good knowledge of either a high level (e.g. COBOL or PL/I) or a procedural language (e.g. CLISTs or REXX).
Duration
5 days

Course Code
AS
Contents
Introduction
Programming Languages; the assembly process and program structure; Assembler directives; macro instructions and Assembler instructions; instruction formats; storage locations and addresses; machine instructions and symbolic statements; hexadecimal and the EBCDIC code.


Handling character data
Defining fields; storage & constants; Dummy Sections (DSECTs) and Equates (EQU).


Comparisons, branching & structure
Comparison instructions; branching instructions; program skeleton, the location counter and addressing; register convention and Save Area chaining; subroutines - getting to them and back.


Input/Output
File Handling and the DCB macro; OPEN, GET, PUT and CLOSE.


Packed decimal arithmetic
Decimal arithmetic instructions; add decimal; subtract decimal; multiply decimal; divide decimal; compare decimal; zero and add decimal; shift and round decimal.


Binary instructions
Load and store; binary arithmetic; conversion and bit shifting instructions.


Translations and bit manipulations
OR'ing; AND'ing; exclusive OR'ing and translate instruction.


Dumps and MVS error reporting
MVS dumps; stand-alone dumps; SVC dumps and user ABEND dumps; snap dumps and symptom dumps; Program Interruption Codes (PICs); dump examples.


The program listing
ASM H listings; HLASM listings; the source and object program listing; the relocation dictionary; the symbol and literal cross-reference; the diagnostic cross reference and summary; options summary (HLASM).


Dump Analysis & Debugging



24, 31 and 64 bit addressing
All the mode switching instructions, focusing on BASSM and BSM