IBM Mainframe Assembler – Introduction
|Duration: 10 days|
|Participants: This course is designed for programmers already experienced in another procedural language such as COBOL.|
Upon successful completion of this course you will be able to:
- Code, link and execute structured assembler programs using the fixed point binary instruction set, the packed decimal instruction set, and most of the non-privileged logical character instruction set.
- Read and interpret an assembler listing, and correct diagnostics.
- Debug program interrupt abends, such as S0C7, S0C9, S0C6, S0CB.
- Convert between symbolic and explicit machine instruction code, and interpret instructions in a hexadecimal dump.
- Use DS, DC (including C, X, F, H, D, P, Z, A, and V type constants), START, CSECT, DSECT, ENTRY, EXTRN, USING, DROP, ORG, LTORG, CNOP, and END.
- Format the source listing using TITLE, EJECT, SPACE, PRINT and comments.
- Code the I/O macros (OPEN, CLOSE, GET, PUT, DCB) for QSAM FB MOVE mode.
- Call a sub-program, pass data and access that data in the sub-program, using standard entry linkage and exit linkage.
- Course topics include data definition, use of packed decimal and fixed point binary instruction sets, looping techniques, formatting and editing output reports, modular and self-documenting code, standard entry and exit linkage, writing main and sub-programs with standard linkage and data passing, DSECTs, macros for QSAM move mode I/O, Boolean instructions for bit manipulation and testing, and debugging techniques.
- Students code and run many programs and sub-programs to reinforce the lecture material. This assembler is used on zSeries and OS/390 mainframe computers, running z/OS or OS/390 MVS operating systems.
|Prerequisites: Non-programmers should first learn program logic. A knowledge of JCL is recommended.|
|Format: Lecture and hands-on workshops.|
Hexadecimal, binary, decimal
Absolute addresses (24 bit and 31 bit)
Relative addressing - base displacement concept
Boundaries (H, F, D)
- Data Definition
Character / packed decimal / fixed point binary / zoned decimal
DS and DC instructions
Constants - C, X, B, F, H, D, P, Z
Introduction to A and V address constants
Using the IBM Reference Summary Booklet
Redefining fields and records - ORG
- Computer Listing: Overview
Linkage editor listing
SYSUDUMP layout - control blocks, registers, unformatted dump
Locating data in the dump
- Assembler Fundamentals
Machine instruction formats (RR, RS, RX, SS, SI, S)
Operands - explicit code, symbolic addresses, literals
Basic machine instruction set for fixed point binary instructions
Data conversion - PACK, CVB, CVD, UNPK, MVZ
Arithmetic - A, AH, AR, S, SH, SR, M, MH, MR, D, DR
Moving data - LM, L, LH, IC, STM, ST, STH, STC, MVC
Branching - B, BR
Comments and structured coding considerations
Basic QSAM macros
OPEN, GET, PUT, CLOSE, DCB
Using the Data Management Macro Instructions manual
Basic assembler instruction set - CSECT, USING, END
Base register - USING, LR
Entry and exit linkage - concepts and code
Basic CLG JCL
System/370 Reference Summary Booklet
S/370 Principles of Operation
Assembler Programmer's Guide
- Standard Instruction Set, Moves, Compares, Branches, Modularization
Move instructions - MVI, MVC, MVZ
Compare fixed point binary data - CR, C, CH
Extended mnemonic branching instructions - BR, BH, etc.
Self documented programs
Modular programming - BAL, BALR, BR (to return)
Formatted source listing - TITLE, EJECT, SPACE, PRINT
- Decimal Instruction Set
Arithmetic - AP, SP, MP, DP
Moving data - ZAP
Conditional Branching - CP
Truncating and rounding techniques - SRP
Editing reports - ED, EDMK
- Introduction to Debugging
Using the System Messages and System Codes manuals
Debugging dumps - S0C7, S0CB, S0C6, S0C9
- Linking Multiple Programs
Address constants - A and V
Loading Addresses - LA (MVS/XA considerations)
Program linkage and CALL statements
- Logical Instruction Set
And - turn bits off - NI, NC, NR, N
Or - turn bits on - OI, OC, OR, O
Exclusive or - flip bits and zero out fields— XI, XC, XR, X
Testing bits - TM
Conditional branch - extended mnemonic instructions
- Looping and Introduction to Table Handling
Defining one dimensional tables
Addressing using RX instructions and indexing
Addressing using SS instructions
Controlling loops - BCT, BCTR, BXLE
- Introduction to Advanced Techniques (Optional)
Multiple base registers
Placement of literals - LTORG
Conditional no-ops - CNOP
Data shifting - SLA, SRA, SLDA, SRDA, SLL, SRL, SLDL, SRDL
Testing and validating data - TRT