Apple IIgs GS/OS Internals

This book is for advanced Apple IIgs programmers and curious people. It is an unofficial publication from Brutal Deluxe Software and all the information given herein are related to the Apple IIgs System 6.0.1 version. This book is the result of a 3-year understanding of the inners of GS/OS which was done in order to build a File System Translator for the system.
This book may be seen as the GS/OS reference volume 2. It contains information described in the first volume, gathers data from external reference specifications and technotes.


  • Preface
    • About this book
    • Copyright information
    • Important note
    • References
    • Online resources
  • Memory usage
    • GS/OS memory map
    • GS/OS vector space
    • GS/OS bank E1 globals
    • GS/OS bank 00 globals
    • GS/OS event codes
    • GS/OS error codes
  • GS/OS Buffers
    • GS/OS system buffers
    • GS/OS direct page map
  • System service calls
    • About
    • System Service Dispatch Table
    • Making a System service call from an application
    • System service calls description
  • GS/OS Records
    • Virtual Pointers
    • Volume Control Record
    • File Control Record
    • Interrupt Control Record
      • Interrupt Identification Table
      • VRN to VI Translation Table
      • Vector Table
      • Vector Dispatch Table
  • File System Translators
    • Header
    • Present and future FSTs
    • Calls handled by FSTs
    • FST system entry routine

  • Appendix – GS/OS technotes
    • GS/OS #1 Contents of System Software Distribution Disks
    • GS/OS #2 GS/OS and the 80-Column Firmware
    • GS/OS #3 Pointers on Caching
    • GS/OS #4 A GS/OS State of Mind
    • GS/OS #5 Resource Fork Formats
    • GS/OS #6 Drivers and GS/OS Direct Page
    • GS/OS #7 Behavior of SET_DISKSW
    • GS/OS #8 Filenames With More Than CAPS and Numerals
    • GS/OS #9 Interrupt Handling Anomalies
    • GS/OS #10 How Applications Find Their Files
    • GS/OS #11 About EraseDisk and Format
    • GS/OS #12 All About Notify Procs
    • GS/OS #13 GS/OS Reference Update
    • GS/OS #14 The Console Driver Technical Note

This book is dedicated to the memory of Joe Kohn (1947-2010)
Joe was the reseller of Convert 3200, our graphic converter software