Apple HD20 Hard Disk Firmware source code
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Use as http://john.ccac.rwth-aachen.de:8000/as/index.html build 2011-08-02 
or later to assemble these files.

This disassembly has been created from scratch. As the HD20 firmware has been
derived from the Widget code, many of the Widget comments could be reused 
here. The files assemble into Rev. 3372 (342-0343-B).

A HD20 controller supports two different HDA mechanisms: Apple Nisha and 
Rodime RO552. Nisha is a 5.25" drive with 610 tracks and 2 heads, RO0552 is a
3.5" unit with 305 tracks and 4 heads. The drive type fitted is detected from 
the servo response.

The source code is still incomplete because the Z8's internal memory 
(341-0339-A) part is missing. Many subroutine calls go into this 0x0000 .. 
0x07FF region and their meaning could only be guessed now. So this is still 
work in progress. 

I do not own a HD20, therefore I was not able to dump the Z8 ROM myself.



Patrick


