On Fri, 7 Oct 2005, Allison wrote:
FD55A single sided 48tpi 300rpm
FD55B Two sided 48tpi 300 rpm
FD55E single sided 96tpi 300rpm
FD55F two sided 96tpi 300rpm
FD55G two sides 96tpi 300/360rpm
and a few "sub-models" with various minor differences.
It is not so
good with hard-sectored, or NO-index reading.
Works great with NS* hard sector
controller at 300rpm.
not always so happy with some of the poorly designed flux-transition
adapters for PCs ("Apple Turnover"). And, if you need to suppress index
pulse (to read certain far from spec WD formats on 765, interrupt the
signal in the cable, NOT by covering index hole.
QD is for those systems that DD was 360k (48tpi). QD
system could be 720k,
780k(amproLB).
also 800K (5*1024, 10 * 512, etc.), and 640K (16*256, 8* 512
(supported by
XP!!! (/t:80/N:8))).
And, there were a few oddball systems that ran 70 or 77 tracks, instead of
80.
hit DD there were SSDD(160K raw), DSDD(400k raw) and
then DSQD(800k raw)
depending on your definition of "raw"
~250K, ~500K, ~1000K unformatted capacity.
and there was even a SSQD(400K raw) (yep 96tpi DD data
rate and only one side).
This is why 5.25 floppy was so much confusion as it
morphed from the 35 track
SA400 through the FD55GFR.
YEP!
There there were the formats applied.. [open can,
worms!, run!]
OK, we'll try not to go there