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IBM Mainframe Assembler – Introduction
| Duration: 10 days |
| Participants: This course is designed for programmers already experienced in another procedural language such as COBOL. |
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Objectives:
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. |
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Overview:
- 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. |
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Topic Outline:
- Background Numbering systems Hexadecimal, binary, decimal Addressability 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 Assembler listing 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 Manuals System/370 Reference Summary Booklet S/370 Principles of Operation Assembler Language 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. Structured programming 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) Linkage editor Program linkage and CALL statements DSECTs - 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 |
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