Re: Commodore drives can be controlled on Apple II serial!

[doug.cotton@cmdweb.com (Doug Cotton)]

In article <1998032003560701.WAA11098@ladder01.news.aol.com>,
dougkalley@aol.com (DougKalley) wrote:

> Seems feasible. I would say a 1541 is more common than the 1571 (which runs in
> 1541 mode also). I think I will have to play around with that, and ask anyone
> on cbm-hackers if they have a rom map and the serial codes anywhere. I have
> been trying to find a fun Ml project lately.

As indicated by someone else, the 1541 is only GCR. The 1571 and 1581 do
MFM (as well as the CMD FD-2000 -- shameless plug), and all of these latter
drives run on a 2 MHz processor and support burst serial (which is much
faster than the stock serial).

Also, as someone indicated, the Commodore serial port wasn't RS-232.
Implementing this on a dedicated RS-232 port wouldn't be feasible, but it
could be done if the RS-232 port were done with a general I/O chip
controlled purely by software. 

The Commodore serial bus, commonly referred to as the IEC serial bus, was
basically a serialized version of the IEEE-488 bus (which is what was used
on earlier Commodore computers like the PET). 

Commented ROM listings of the 1541 are available in the book, Anatomy of
the 1541 (Abaacus Books) which can be purchased new from CMD. A similar
book existed for the 1571, 1571 Internals (Abacus Books). The latter isn't
available from us, but Abacus may have a few left
(http://www.abacuspub.com). The computer side of the code can be found in
Anatomy of the Commodore 64 (Abacus Books) and 128 Internals (Abacus
Books). The latter contains the computer side of the burst serial protocol
used for burst mode loading.

-- 
Doug Cotton <doug.cotton@cmdweb.com>

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