30 Mar
2023
30 Mar
'23
10:48 a.m.
On Thu, 30 Mar 2023, Chuck Guzis via cctalk wrote:
Absent any alignment issues, or dirty heads, just
about any HD drive
(e.g. Teac FD235HF) is equally facile in both DD and HD media. Quite
often, a DD-only (e.g. Teac FD235F) drive will have performance inferior
to that of the HD-DD drives.
Other issues that might crop up in reqplacement, such as READY on pin 34
versus DISK CHANGED, does have to be taken into account.
some of the exceptions:
The drives in many IBM PS/2 machines don't seem to have a media
sensor, so they can't tell the difference between "720K" and
"1.4M" disks.
"720K" is about 600 Oersted, and "1.4M" is about 750 Oersted, so they
are
close enough that sometimes one can get away with using the wrong one.
There once existed single sided drives. Such as the original Shugart SA300
They were used in early Gavilans, but were replaceable with double sided,
especially the SA350, which could use the Gavilan's custom SA300 bezel,
Epson Geneva PX8 was 40 cylinders, intead of 80, with 67.5tpi, instead of
the usual 135tpi.
"2.8M" will also work, it has a media sensor for te ED disks.
The original Sony FULL height drives were at 600RPM, and had a different
interface.
The Tandy Portable Disk Drive, for the model 100, was weird and a half.
--
Grumpy Ol' Fred cisin(a)xenosoft.com