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README.md
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README.md

Tandy 1000HX BIOS

What is this

The Tandy 1000hx BIOS disassembled.

This is still WIP.

TODO:

  • Finish analyzing graphics code
  • Finish analyzing EEPROM code
  • Finish analyzing keyboard code
  • Analyze all the floppy disk handler
  • And analyze what's left
  • Review IDA Pro autogenerated comments. Some of them are not valid for the Tandy
  • And probably much more

How to read it

EEPROM

There are 4 words (1 word == 2 bytes) to store data.

word 0

15: 14: 13: 12: 11: 10: 9: 8: 7: 6: 5: 4: 3: 0=7.16 Mhz. 1=4.77 Mhz. 2: Should be 0, otherwise "word_1019f" is 0xffff 1: Drive B: 0=3 1/2, 1=5 1/4 (or the other way round?) 0: Drive A: 0=3 1/2, 1=5 1/4 (or the other way round?)

word 1

15: 14: 13: 12: 11: 10: 9: 8: 7: 6: 5: 4: 3: 2: 1: 0: video card: 0=color, 1=monochrome

word 2

15: 14: 13: 12: 11: 10: 9: 8: 7: 6: 5: 4: 3: 2: 0,1: number of diskettes installed minus 1

word 3

15: 14: 13: 12: 11: 10: 9: 8: 7: 6: 5: 4: 3: 2: 1: 0:

References