7 Oct
2005
7 Oct
'05
5:11 p.m.
Subject: Re: TEAC FD-55GFR = Quad Density?
From: Fred Cisin <cisin at xenosoft.com>
Date: Fri, 07 Oct 2005 16:34:17 -0700 (PDT)
To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at
classiccmp.org>
BOTH.
The 55F is "720K" only; 55G and GFR are 1.2M.
The 55GFR is a reliable and versatile drive.
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
It is not so good with hard-sectored, or NO-index
reading.
Works great with NS* hard sector controller at 300rpm.
The difference between 1.2M and "720K",
sometimes called "QUAD density" by
the marketing people, are 360 v 300 RPM, 250K v 500K sata transfer rate,
and different current levels at the heads (controlleable on the
interface). They are both 96TPI.
QD is for those systems that DD was 360k (48tpi). QD system could be 720k,
780k(amproLB).
To do "quad" in an "HD" drive
requires stepping at 96TPI, but the data
transfer rate, and current levels at "360K" levels.
Or the common QD systems I have the data rate is same as DD (still 300rpm)
but there are twice as many tracks or quad. 5.25 floppies started at 80k
(sa400 single density one side 40 tracks (48tpi) all the way to near 800k
(FD55F, DD, two sides 96tpi). There were enough marketing names to the
capacity jumps to confuse even the marketers. however once the data rates
hit DD there were SSDD(160K raw), DSDD(400k raw) and then DSQD(800k raw)
and there was even a SSQD(400K raw) (yep 96tpi DD data rate and only one side).
that last one was know widely as RX50 and also appeared using FD55E on
Visual 1050. There was the 1.2mb PC thing.
This is why 5.25 floppy was so much confusion as it morphed from the 35 track
SA400 through the FD55GFR.
There there were the formats applied.. [open can, worms!, run!]
Allison