22 Jul
2013
22 Jul
'13
3:43 p.m.
On Mon, 22 Jul 2013, Tony Duell wrote:
which is why although excessively PC-Centric (easily 250K to 400K), "360K"
and "1.2M" are unambiguous. Phillip referred to 40track/DD, which is
also unambiguous due to the non-existence of 20 cylinder drives, and
80track/HD, which is also unambiguous due to the nonexistence of high
density 40 cylinder drives.
If he were to have asked for 80track/DD, THEN it would have been
ambiguous.
hence "probably"
"putting numbers on the face would CONFUSE anybody who is as clueless as
we are"
In this
context, it is completely clear what types of drives you are
referring to. Some of the many confusions in the past have involved more
obscure systems, people who refer to 40 cylinder double sided drives as
"80 track", lack of differentiation between 96tpi DD and 96tpi "HD",
etc.
Err, _I_ refer to a 40 cylidner 2 head drive (what a PC person called a
'360K drive') as 80 track. It has 40 cylinders, each of them consists of
2 tracks (one on each surface of the disk). if any, are
96tpi DD (aka "720K 5.25"). If they are "half-height", then
there are probably no single sided, etc.
There _were_ single-sided half-height
drives, but they are not at all
common in PCs. I think it;'s a reasonable assumption that all of
Liam's drives are
either '360K (40 cylinder, 2 heads, 300 rpm) or '1.2M' (80 cylidner, 20
heads, 360rpm, HD data rate).
my assumption, as well.
_My_ first test would eb to stick them on a drive
exerciser. I can stick
a scracth disk in and measure the intex pulse freqeuncy to get a good
idea of the spindle speed. I can also trystepping in my 40 cylinders nd
see if the heads cover half or all of the disk surface. The only problem
with that method is that few people one a floppy drive exerciser any more.
much less, have them handy at boot sales, etc.
BUT, that provides more accurate information than relying on the labels on
the drives, AND eliminates any that won't turn or step.
WHen IBM
introduced their 1.2M drive, they realized that they needed to
label the two types. But, being rather less than clueless, they chose to
Yes,
that was ridiculous, I would have expected better from IBM.
Why thy didnt simply mark '360K' or '1.2M' on the faceplates is beyond
me. The suffix letters on TEAC drives seem to be fairly
logical :
A : 40 cylidner single-head
B : 40 cylinder double-head ('360K')
F : 80 cylinder double-head ('720K')
G : 80 cylinder double-head HD 360RPM ('1.2M')
H : 80 cylinder double-head HD 300rpm ('1.44M')
don't know.
Most manufacturers' numbering systems have some clues in them.
"16" within the number often means 1.6M unformatted (1.2M formatted)
"-4" might mean 80cylinder double density, or it might mean 80 cylinder
"high" density.
--
Grumpy Ol' Fred cisin at xenosoft.com
are the common ones
E : 80 cylinder single
head (like an RX50 :-))
I think I've seen.
C and D I ahev not. Were those 77 cylinder drives or something?