Re: Serial Slave 0.7b out

From: Nicolas Welte (
Date: 2002-02-27 15:32:44

Marko Mäkelä wrote:
> Christopher Phillips wrote:
> > Should be any that support M-W and M-E, has a page I can use
> > for code at 0x500, ...
> A wild idea: How much does the hardware of the PET disk drives vary?
> Would a custom routine that runs on the DOS CPU work on all types of
> drives ([234]040, 8[02]50 and 90[69]0)?  Of course, the protocol would

Simply speaking, the hardware doesn't differ at all between those drives. The
differences are very minor and are on the controller CPU's side (6502 vs
6504, though the memory map stays the same), the 8x50s/1001 run a faster GCR
clock speed, and the harddisks have a SASI bus hooked up on the controller
side. I think the 8x50 boards even have a jumper that allows them to run in
the slower 4040 mode. 

The differences in software might be bigger, the mapping of memory locations
has probably changed during evolution from DOS 1.0 to DOS 3.0.


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