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Radio Shack TRS-80 Model II Technical Reference Manual

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The TRS-80 Model II Technical Reference Manual is Radio Shack's service reference for the TRS-80 Model II, catalogue number 26-4921, copyright 1980. The scan has 204 pages. It covers the display console (CPU, floppy disk controller, video/keyboard and memory boards, the motherboard, the Motorola and RCA video monitors, the Shugart SA800 floppy drive and the AA11080 power supply), the keyboard unit, and the Disk Expansion Unit with its CDC 9404B drives and AA11100 power supply.

The manual describes itself as theory of operation plus checkout procedures that trace a fault to a subassembly or board "but no lower", with repairs limited to replacing subassemblies. Each section nevertheless ends with a full parts list giving every component's value and manufacturer's and Radio Shack part numbers, and most sections include the schematic.

Contents

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Section and printed page numbers, from the manual's table of contents:

  • I. System description (p. 1): display console, keyboard unit, peripheral interfaces; power supply ratings and minimum loads (p. 3); power distribution (pp. 5-6)
  • II. Troubleshooting and replacement (p. 7): power-on diagnostics and boot error messages, detailed troubleshooting steps and sync signal timing (pp. 9-10); disassembly and reassembly (pp. 11-14); subassembly part numbers (p. 15)
  • III. CPU module (p. 17): theory, parts list (pp. 25-27), schematic in three sheets (pp. 29-31)
  • IV. Floppy disk controller board (p. 33): FD1791 operation, port tables, parts list (pp. 50-52), schematic (pp. 53-54)
  • V. Video/keyboard interface (p. 55): MC6845 CRT controller, keyboard interface, parts list (pp. 69-70), schematic (pp. 71-72)
  • VI. Memory board, 32K and 64K (p. 73): jumper options and verification (p. 77), parts list (pp. 81-83), schematic (p. 85)
  • VII. Video monitor (p. 87): Motorola version with safety warning (p. 90), service notes and adjustments (p. 91), troubleshooting guide (pp. 92-93), parts list (pp. 101-102) and schematic (p. 103); RCA version (p. 105) with service adjustments (p. 106), parts list (p. 108) and schematic (p. 109)
  • VIII. Floppy disk drive (p. 111): SA800 jumpers and disk termination (p. 113), mechanical parts list (pp. 114-115)
  • IX. AA11080 power supply (p. 117): test set-up and load board values, no-output checks (pp. 119-120), performance test and ripple limits (p. 121), operating characteristics (pp. 122-123), schematic (p. 124)
  • X. Card cage and motherboard (p. 125): slot order and parts list (p. 127), bus signals (pp. 128-129)
  • XI. Keyboard unit (p. 133): cables, code map, parts list (pp. 137-139), schematic (p. 140)
  • XII. Peripheral interfaces (p. 141): serial, parallel and disk expansion connectors, rear view (p. 146)
  • XIII and XIV. Disk Expansion Unit (p. 147) and its troubleshooting (p. 153), with parts lists for the unit and the CDC 9404B drive (pp. 159-165)
  • XV. AA11100 power supply (p. 167), the Disk Expansion Unit's supply
  • XVI. Illustrated parts breakdown (p. 175): case and chassis assemblies

What this manual does not contain

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  • The section XVII appendices listed in the contents (Zilog, Western Digital and Motorola data sheets, and the Shugart SA800/801 and CDC 9404B drive manuals) are not in this scan, which stops at the appendix divider page.
  • The AA11080 power supply section has a schematic with designators only. It gives no parts list and no component values for the supply.
  • The SA800 drive section has a mechanical parts list only; for the drive electronics the manual refers to the Shugart manual.
  • For memory and system tests beyond the boot checks, the manual refers to Radio Shack's diagnostic diskette (AXX2012) and the separate TRS-80 Model II Troubleshooting Manual, neither of which is included.
  • The printed page numbers run on across fold-out and blank pages that are missing from the scan, so the PDF page number is between 11 and 19 higher than the printed one.

Pages that cite this document

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Download: Radio Shack TRS-80 Model II Technical Reference Manual (26-4921, 1980).pdf

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