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IBM Mainframe Assembler for Programmers
| Duration: 15 days |
| Participants: This course is designed for programmers already experienced in another procedural language. |
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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, S0C1, S0CB. - Troubleshooting skills are developed throughout the course. - Convert between symbolic and explicit machine instruction code, and interpret instructions in a hexadecimal dump. - Use DS, DC (including C, X, F, H, S, P, Z, A, and V type constants), START, CSECT, DSECT, EXTRY, 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. - Explain the use of standard entry linkage and exit linkage. - Use appropriate assembler coding for above and below the line programs. - Describe HLA (High Level Assembler) features. - Describe the organization and use of the IBM manuals used in this course. |
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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, arithmetic for large numbers, debugging techniques, and MVS/XA coding considerations. - Students code a variety of programs and sub-programs to reinforce the lecture material. |
| Prerequisites: Non-programmers should first learn program logic. 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 DS and DC instructions Constants - C, X, B, F, H, D, P, Z Introduction to A and V address constants Using the IBM System/370 Reference Summary Booklet Redefining fields and records - ORG - Computer Listing: Overview Assembler listing and control blocks Linkage editor listing and control blocks 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 IBM Reference Summary Booklet IBM Principles of Operation Assembler Language manual Assembler Programmer's Guide manual MACHINE EXERCISE #1 - Standard Instruction Set, Moves, Compares, Branches, Modularization Move instructions - MVN, MVI, MVC, MVZ Conditional Branching with fixed point binary data Compare - CR, C, CH Extended mnemonic instructions Data validation techniques Structured programming Self documentation Meaningful and easy to read comments and code Meaningful symbolic names and labels Modular programming - BAL, BALR, BR (to return) Formatted source listing - TITLE, EJECT, SPACE, PRINT MACHINE EXERCISE #2 - Decimal Instruction Set Arithmetic - AP, SP, MP, DP Moving data - ZAP Conditional Branching - CP MACHINE EXERCISE #3 Truncating and rounding techniques - SRP, MVO Editing reports - ED, EDMK MACHINE EXERCISE #4 - Debugging Using the System Messages and System Codes manuals Debugging dumps - S0C7, S0CB, S0C6, S0C9, S0C1 - Linking Multiple Programs Modular programming Address constants - A and V Loading Addresses - LA (MVS/XA warning) Linkage editor Program linkage and CALL statements DSECTs MACHINE EXERCISE #5 - 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, BCT, BCTR MACHINE EXERCISE #6 - Looping and Introduction to Table Handling Defining one and two dimensional tables Addressing using RX instructions and indexing Addressing using SS instructions Controlling loops - BCT, BCTR, BXLE, BXH MACHINE EXERCISE #7 - Introduction to Advanced Techniques Advanced loop control techniques Multiple base registers Placement of literals - LTORG Conditional no-ops - CNOP Data shifting - SLA, SRA, SLDA, SRDA, SLL, SRL, SLDL, SRDL Setting program mask - SPM Logical arithmetic (for large numbers) - AL, ALR, SL, SLR Advanced load instructions - LTR, LCR, LPR, LNR Translating data - TR Testing and validating data - TRT Executing one line subroutines - EX - Summary and Review |
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