Labelling of drives (was: 3.5" floppy drive in IBM XT?

From: Fred Cisin <cisin_at_xenosoft.com>
Date: Mon Apr 14 13:59:17 2003

> >I have a highly original late production XT, with the 640k system board,
> >720k hh floppy, 360k hh floppy, and full height IBM 20mb hard drive.
> >Interesting features include a Y cable to power both floppy drives from
> >the PSU connector (Y cable has black wires, and a cloth tag with IBM
> >part number 6480173). Also, the 720k drive has a plain blue eject
> >button. The 3.5" drives from the PS/2 series were labelled 1.44m or
> >2.88m as appropriate.

PS/2's ALSO had 3.5" drives with a blue eject button labelled 720K.
The 720K was out for a while before 1.4M or 2.8M existed. All IBM
3.5" drives with unlabelled button (IN THOSE DAYS) were 720K.

> The 360k drive has an asterisk on it, just like
> >on the optional AT 360k drive. Apparently the IBM convention for 5.25"
> >drives was that if it was a full height floppy, drive then it was 360k,
> >if it was a half height drive it was assumed to be 1.2M, unless it had
> >an asterisk, then it was 360k.

Full height drives could also be 720K, although that was never used by IBM
in the U.S.
There were 1.2M full height drives (never used by IBM), but they are now
rather rare.


Half height 360K drives existed BEFORE the existence of 1.2M.
The Qume 142 (one of the worst drives EVER) HH drives used in the Jr and
in the "Portable PC" did NOT have asterisks.

LATER, when IBM started selling ATs with 1.2M drives, they started to put
asterisks on 360K HH drives for the AT.

Thus, a HH drive with an asterisk is a 360K that came out after the 1.2M.

An IBM HH drive without an asterisk could be:
        a 360K (from before the 1.2M)
        a 1.2M
        an aftermarket drive of any size
Received on Mon Apr 14 2003 - 13:59:17 BST