ruud.baltissen_at_abp.nl
Date: 2007-08-27 13:42:16
Hallo Bill,
> Could the D9090 / D9060 code have answers?
Nope. AFAIK there isn't any documented source listing of them. So I
started to create one myself. The only thing I can say so far that it
looks a bit like the code of the 8050. I have the documented source of
the 8050 (PDF if interested) but, unfortunately for the most of you, in
German. I also started to translate that one in English.
But nevertheless both the sources are not really helpfull. The reason is
that the CBM file system is based on this track and sector pointer at
the beginning of each sector which only supports drives up to 16 MB.
That's why I went for four bytes that can handle up to 2 TB. If it was
easy to port the two-byte pointer to a four-byte one (and that's how it
looked), I wouldn't have called for help :)
Also don't forget that the 8x50 and 90x0 drives have two processors
which there each own code and memory which complicate things as well.
And why using a 1541 as base? They are quite common and cheap, certainly
compared to a 1581. I wouldn't think of hacking my only working 1581.
The advantages the 1581 and 1571 have above a 1541 are the memory (1581
only), 2 MHz mode and Burst mode. But both have a (maybe) big
disadvantage: they already have an 32 KB ROM onboard. Adding extra ROM
is not easy.
I'll just go on struggling with the code :)
--
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/ / |_/ Groetjes, Ruud
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\___| URL: Ruud.C64.org
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