TRSDOS 2.3 Decoded and Other Mysteries

written by Matthew Reed

Title:TRSDOS 2.3 Decoded and Other Mysteries
Publisher:IJG, Inc.
Publication date:
Number of pages:304
TRSDOS 2.3 Decoded and Other Mysteries

TRSDOS 2.3 Decoded and Other Mysteries was written by James Lee Farvour and published by IJG in 1982. It was volume six in the TRS‑80 Information Series.

In a way, this book was a companion to James Lee Farvour’s earlier Microsoft Basic Decoded and Other Mysteries. That book analyzed TRS‑80 Model I BASIC in great detail, describing how each part of the language worked. At the end of the book, it included the commented portion of a disassembly of the BASIC. It did not include the complete disassembly because Microsoft never gave permission for that to be published.

TRSDOS 2.3 Decoded and Other Mysteries, also by Farvour, provides the same type of detailed analysis of Model I TRSDOS. One difference from the previous book is that this book was published with Tandy’s permission and it includes a complete disassembly of TRSDOS 2.3! This disclaimer appears near the beginning of the book:

The TRSDOS 2.3 disk operating system, including the listing of the machine-readable hexadecimal code and assembly language code contained in Appendix II and reproduced in part elsewhere in this book, is owned and copyrighted by Tandy Corporation. Reproduction is by written authorization from Tandy Corporation.

TRSDOS 2.3 Decoded and Other Mysteries consists of ten chapters and two appendices:

  • Chapter 1 provides an introduction to the Model I hardware.
  • Chapter 2 contains an overview of TRSDOS.
  • Chapters 3 through 9 cover the six overlay files, SYS0/SYS through SYS6/SYS, which comprise the bulk of the operating system.
  • Chapter 10 covers the boot loader, BOOT/SYS.
  • Appendix I contains a very detailed look at data structures within TRSDOS.
  • Appendix II contains a complete, commented disassembly of TRSDOS 2.3.

The degree of detail in this book is amazing and every aspect of TRSDOS 2.3 is described in depth. Several bugs in TRSDOS 2.3 are pointed out, along with some possible fixes. It is a great book for anyone who has ever wondered just how TRS‑80 operating systems worked.

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