[abc80] CP/M on the DE1 FPGA card
H. Peter Anvin
hpa at zytor.com
Mon Juni 2 10:37:00 PDT 2014
On 06/02/2014 12:13 AM, Robert Juhasz wrote:
> very nice indeed! how close to (what we know of) the myab bios/card is your implementation?
>
> robert
Not very. I actually have the source code to the MyAB BIOS, but I don't
know the exact details of their hardware. I decided instead to emulate
Mikrodatorn's 64K modification (which I already had implemented)
hardware-wise.
The other thing was I decided to do deblocking in the disk controller
firmware rather than in the BIOS. This was simply a matter of
convenience because I *already* have to do deblocking from 512-byte SD
sectors to 256-byte ABC sectors, and then having an additional
deblocking step to 128-byte CP/M sectors felt rather stupid. So I just
extended the disk controller deblocking support to support 128-byte CP/M
sectors as an alternative to 256-byte ABC sectors. Yes, it is a bit of
a cheat.
-hpa
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