Osborne-1 SD format

From: Steve Thatcher <melamy_at_earthlink.net>
Date: Mon Feb 21 18:39:30 2005

all Intel did was to use the same basic 3270 format and double the number
of sectors to make the OS changes easy. The gaps between real data did not
get as big from SD to Intel's DD. The 1793 and 8272 DD format could not
handle the shorter gaps that Intel used. The TI chip could...

At 07:18 PM 02/21/2005, Dwight K. Elvey wrote:
> >From: "Steve Thatcher" <melamy_at_earthlink.net>
> >
> >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.
>Hi Steve
> As I recall, the M2FM also had a different sector header.
>Unless you could program the header format, just the spacing
>problem was only half the issue.
> >
> >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 - 18:39:30 GMT

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