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",
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).
Mind you, I don;t call it that very often. Most of the time I ralk about
a '40 cylinder' or '80 cylidner' drive. Those terms are unambiguous.
I'm glad that Liam stepped forward! My boxes of
drives are not easily
accessible, other than one apparently new but untested drive in one of the
boxes of books.
Since these are PC (or more likely PC/AT) pulls, we can assume that few,
if any, are 96tpi DD (aka "720K 5.25"). If they are "half-height",
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_ 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.
Do any of them have a star/asterisk embossed on the faceplate?
If so, then those are fairly recent 40t/DD
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
label the wrong one. A special mark on 1.2M would have solved/prevented
the problem. Instead, they marked drives for which there already existed,
even from their own factories, MANY unmarked ones.
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
at one point, IBM sold 3 types of half height drives for their machines
(AFAIK they _were_ selling all 3 at the same time) :
360K 'slimline' for the PCjr and Portable PC (5155) -- no *
360K for the PC/AT (5170) -- with a *
1.2M for the PC/AT (5170) -- no *
To sell 2 different 360K drives at the same time, one marked the other
not is, well....
At least one clone manufacturer (Olivetti?) had little plastic badges to
identify the drives. Alas they fitted onto the case, not the drives, so
were not always correct (particularly if the machine had been upgraded
with generic drives). And of course said badges are useless for
indentifying loose drives.
Therefore, if there is NOT a star/asterisk, then the
drive is a
40t/DD from before the time of the mark,
a 40t/DD from a manufacturer that didn't go along, or
In general, the easiest ID will be by model number.
On Mon, 22 Jul 2013, Al Kossow wrote:
TEAC 55B 360K 40T
TEAC 55G 1.2M 80T HD
Here's a few more drive model numbers to check against:
TEAC 55FG 1.2M/"720K" 80T DD/HD
TEAC 55F "720k" 80T DD
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')
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?