Re: Apple// CP/M question

[Roy and/or Janet Miller <millers@inetnebr.com>]

David Empson wrote:

> Roy and/or Janet Miller <millers@inetnebr.com> wrote:
>
>
> >
> > The fact is that there was no standard disk format for CP/M on 5.25"
> > disks, or for that matter the occasional machine that used 3" or 3.5" inch
> > disks.
>
> We have a CP/M kitset machine at work (in a suitcase!) which we used
> actively until about 1990, and have occasionally used since then.
>
> It has 8" and 5.25" drives.  The standard CP/M disk format was a single
> sided single density 8 inch disk (40 tracks, 128 bytes per sector, but I
> forget how many sectors per track: possibly 32, which would make it 160
> KB).

You are quite right about the 8" format, which is why I didn't mention it. As
far as I know, the SSSD format for 8" disks was created by IBM (on what machine
I haven't the faintest idea), however, the strength/weakness of CP/M was that
each hardware vendor could create whatever format they wished. Kaypro used (I
think) the Xerox 850 format. I have a piece of software that will copy files
from various CP/M 5.25" formats, if I remember correctly there are something
like 40 different formats that are options.

Roy

> This was the format used by Digital Research to distribute the
> base operating system.
>
> This particular system also supported double sided double density 8 inch
> disks (77 tracks, 512 bytes per sector, 17 sectors per track, 2 sides,
> for 1309 KB).  It also supported high density 5.25" disks with the same
> format.