15 Sep
2013
15 Sep
'13
2:59 p.m.
On 09/15/2013 01:26 PM, Fred Cisin wrote:
1) My AT 1.2M drives (a sloppy, but not very ambiguous
name for it) can
also read and write 360K disks (a very sloppy but not very ambiguous name
for it).
BUT, not all can!
One of the very first "1.2M" drives that I got (an EARLY Mitsubishi 4854
with FIFTY pin interface connector!) could not reliably do "360K"
The speed was fixed at 360RPM (which is easily compensated for by a
300Kbits per second data transfer rate), and there was no provision for
alternate write current. LATER 4854 drives could do 360K just fine, and
switched to a 34 pin connector.
At the time, it made perfect sense, particularly in the world of
Japanese computing. NEC trotted out the PC98 model for PCs, which is
nothing like the IBM one. One of the more interesting aspects was that
the floppy format between 8", 5.25" and 3.5" disks is exactly the
same--8 xectors of 1024 bytes per track. There simply was no need for a
dual-speed 5.25" drive. I still have a couple of the Mitsubishis
stashed away. (The PC98 3.5" drives also spin at 360 RPM). Very logical.
I seem to recall that NEC had a sort of sub-contractor for US support
and information down in the San Diego area. I may still have some of
their literature. I believe there was also an article or two in Tech
Specialist (or one of its later aliases) about the big differences
between the PC and PC98 platforms.
But you certainly see the NEC PC98 formats all over the CNC
world--another place where CP/M 68K was popular.
--Chuck