24 Mar
2025
24 Mar
'25
9:58 p.m.
TEAC FD-55F floppy drives
https://retrocmp.de/fdd/teac/fd55f.htm
The TEAC FD-55F never appeared in the world of IBM compatible computers. Why is that?
Because it was simply superfluous in the DOS world.
The TEAC FD-55F is a double-sided 5.25 inch drive that can write 96 tracks per inch (TPI)
with 9 sectors per track. In other words, the capacity of a floppy disk is 720 KByte.
There were Radio Shack and other computers (NCR, etc.) that used this format (DSQD).
This corresponds to the capacity of the standard 3.5-inch double-density (DD) drive.
The 3.5-inch floppy disk format was supported since DOS version 3.2.
Introduction of 3.5” drives and disks by IBM (mid-1980s) was one reason why the 5.25 inch
drives with 720 KByte storage did not find their way into the IBM world.
==
Further in the above web link:
Changing a Teac FD-55GFR drive to a FD-55F drive ... or,
How do I get my drive to spin at 300 RPM instead of 360 RPM ?
gb
24 Mar
24 Mar
10:32 p.m.
New subject: FD-55B head loose
On Mon, Mar 24, 2025, 2:59 PM Gregory Beat via cctalk <cctalk(a)classiccmp.org>
wrote:
TEAC FD-55F floppy drives
https://retrocmp.de/fdd/teac/fd55f.htm
The TEAC FD-55F never appeared in the world of IBM compatible computers.
Why is that? Because it was simply superfluous in the DOS world.
The TEAC FD-55F is a double-sided 5.25 inch drive that can write 96 tracks
per inch (TPI) with 9 sectors per track. In other words, the capacity of a
floppy disk is 720 KByte.
There were Radio Shack and other computers (NCR, etc.) that used this
format (DSQD).
Thr DEC Rainbow too. I upgraded by RX50s to a pair of these. There are
patches to 2.11 and 3.10b for 800k floppies. But it wasn't long after that
that I got a 38MB hard disks and i went back to 400k floppies.
The RX50s just had different padding between sectors so 10 would fit per
track. All the other parameters were the same.
If you didn't want to boot off the floppies, my IMPDRIVE package could
read, write or format them.
I pulled them out of storage during covid, but couldn't make them work
reliably again. :(.
Warner
This corresponds to the capacity of the standard 3.5-inch double-density
(DD) drive.
The 3.5-inch floppy disk format was supported since DOS version 3.2.
Introduction of 3.5” drives and disks by IBM (mid-1980s) was one reason
why the 5.25 inch drives with 720 KByte storage did not find their way into
the IBM world.
==
Further in the above web link:
Changing a Teac FD-55GFR drive to a FD-55F drive ... or,
How do I get my drive to spin at 300 RPM instead of 360 RPM ?
gb
11:31 p.m.
New subject: FD-55B head loose
On 3/24/25 13:58, Gregory Beat via cctalk wrote:
TEAC FD-55F floppy drives
https://retrocmp.de/fdd/teac/fd55f.htm
The TEAC FD-55F never appeared in the world of IBM compatible computers. Why is that?
Because it was simply superfluous in the DOS world.
The TEAC FD-55F is a double-sided 5.25 inch drive that can write 96 tracks per inch (TPI)
with 9 sectors per track. In other words, the capacity of a floppy disk is 720 KByte.
If by the FD55F not being used in the world of PC compatibles, perhaps
as to brand, but certainly not as to 96tpi double-density.
The Sanyo MBC-500 series comes to mind with various diskette options.
At Durango, the standard drive for Poppy was the Micropolis 1115-VI
full-height 96 tpi drive. I used one on my 5160 running PC-DOS 2.0--use
was mostly a matter of laying down a disk format--otherwise the drive
functioned as a 720KB drive without system modification.
There were other such systems in the PC-compatible world. It was viewed
as a benefit in competition with IBMs 48 tpi drive choice. The 96 tpi
drive was even common on several 8-bit CP/M systems.
When the official support by IBM and Microsoft for 3.5" DD support,
there was a difference in FAT and cluster size between IBM and Microsoft
MS-DOS. It hardly made a difference with the DOS 2 first sector
containing the DPB, but may have caused confusion in the PC-DOS 1.x world.
--Chuck
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participants (3)
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Chuck Guzis -
Gregory Beat -
Warner Losh