Osborne-1 SD format

From: Steve Thatcher <melamy_at_earthlink.net>
Date: Mon Feb 21 15:33:24 2005

a technical note...

this comment regarding tightly spaced sectors twinged my memory. Anything
based on the 8272/765 (in other words, all normal PC controllers) was not
able to keep the "spacing" between sectors as small as the Intel bot slice
board did. Even the 1793 series was not able to handle this. I had started
work on a DD Intel ISIS controller back then and did a fair amount of
research on this back issue. The only controller chip I found that was
capable of doing both SD and Intel DD was a TI TMX99XX chip (the actual #
escapes me at this time). The chip had very good control of the bytes
between sectors and would have been able to handle the small spacing in the
Intel DD format. Not that this helps Dave's problem, but I figured I would
throw out the comment because it related in a way.

best regards, Steve Thatcher

At 01:38 PM 02/21/2005, Dave Dunfield wrote:
>It's interesting with the Cromemco CDOS disk - the DD area is formatted
>to 10 512 byte sectors/track, and in the DD(360k) drive, I can't read
>them at all - For this test, I pulled the actual Teac drive that I have
>been using on the System-3 (which reads it fine) - it looks like the PC
>controller has touble with the tightly spaced sectors.
>
>Regards,
>Dave
Received on Mon Feb 21 2005 - 15:33:24 GMT