18 Jan
2001
18 Jan
'01
1:56 p.m.
On Thu, 18 Jan 2001, Wayne M. Smith wrote:
My S/23 Service Manual states that two 8 inch drives
were available, the 31SD which was a single sided FM
only drive, and the 51TDF which was a double sided FM
or MFM drive. The disks have 77 tracks per side, and
data can be written on tracks 1 through 74, with 00
reserved for labeling and 75 and 76 for replacement.
Both drives are hard sectored. FM disks can be
formatted with 8, 15 or 26 tracks, with 512, 256 and
128 bytes per track respectively. For MFM the bytes
per sector are doubled.
I believe that you mean SOFT sectored, as the number of sectors
per track in a hard sector disk is determined by the disk and
is only changeable by using a disk with a different hole pattern.
FYI, 5.25" disks came in both 10 and 16 sector hole patterns,
while 8" were 32 hole only to the best of my knowledge.
- don
Using 256 bytes per sector, this gives you from 284K
to
985K per floppy depending on drive/floppy type. This
data corresponds exactly to the data on the
displaywriter disk drive found at :
http://home.planet.nl/~tresmont/ibm-hall.htm
Therefore, I think must use the same format. For what
it's worth, the displaywriter disk drive looks almost
identical to the 5246 unit that goes with the S/23.
-W
I was told that it was the same as the System 36,
and
possibly 23 also.
We were talking about that when be got an old IBM
disk archiver. I
haven't looked into it any further than that,
though.
On Wed, 17 Jan 2001, Joe wrote:
> Does anyone know what disks format the IBM
Display writer uses?
>
> Joe
>