DSQD Drives (Was: RE: Diags/Boot image for Altos 580)

From: Fred Cisin <cisin_at_xenosoft.com>
Date: Sun Mar 17 17:54:01 2002

On Sun, 17 Mar 2002, Tony Duell wrote:
> > correct device (/dev/fd0D720) with dd?
> Not necessarily. /dev/fd0D720 assumes a 'PC like format' -- that is to
> say 512 byte sectors, 9 sectors/track, double sided, 80 cylinders. You
> could have some other sector size (256 byte sectors were very common at
> one time, and I have seen 1024 byte sectors).

Working from failing memory (not recently refreshed), and I already said
that I would NOT get around to looking it up today, ...
If I Recall Correctly, the ALtos MP/M DOES coinscidentally just happen to
run 9 sectors per track with 512 bytes per sector (80 tracks per side)
'Course the DIRectory data structures are CP/M, and unrecognizable to
MS-DOS/Windoze nor any flavor of Unix.

> You can almost certainly read/write these disks under linux using the
> FDRAWCMD ioctl(), but you'll need to understand the PC disk controller to
> write software using that.
Or one could just write the code to operate the 765, or call the INT13h

> fiddling to do. In any case there's no reason not to use a normal PC
> 1/3Mbyte drive.

Hmmm. Tony's definition of "normal PC" must differ slightly from mine :-)
I don't think that I have any 1/3M drives on hand. Although 320K/360K
is close enough to call it that.

Grumpy Ol' Fred        cisin_at_xenosoft.com
Received on Sun Mar 17 2002 - 17:54:01 GMT

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