HP 9121--3 1/2 floppy drive

I have a HP9121 3 1/2 inch floppy drive that is cabled to an HP87XM computer. It seems to be operational but will not recognize the current discs. This floppy drive does not show up in any HP source I have found. Can anyone guide me to the specs on this unit and the discs it was designed to use?


If it is like the 9114B HP-IL drive you need to use either single density disks (very hard to find) or standard disks with the small rectangular density select hole covered up with opaque tape.


And the drives themselves are worth treating with TLC.

Any hint at hesitancy when you press the eject button should be dealt with quickly before you (accidentally) one day rip the heads off it.

Seems to only affect the single sided drives, and only where they've been in hot (and possibly dusty) environments.


I'll give a summary here, but search the archive for Tony Duell's postings on 9114 drives, the mechanism of the 9121is similar to that of the 9114A with the exception that the 9121 is SINGLE sided.

Unlike modern floppy drives, it takes DOUBLE density diskettes (rather than quad density). QD diskettes have
a hole across from the READ-ONLY tab. The 9121 has a "floppy present" sensor over that spot, so if you insert a QD floppy it will not be detected by the drive. According to Tony this is a good thing as QD floppies have different properties from DD floppies, so they are not really interchangable. So you should look for DD floppies on eBay rather than try to use QD diskettes from your PC.

Having said that, you can generally get away with QD diskettes if you block the hole with a piece of tape. Since the sensor is mechanical, transparent tape works.

To format the diskette try

INITIALIZE "label",":D700"

for the left hand drive and

INITIALIZE "label",":D701"

for the right hand drive ("label" can be any string up to 6 characters long)

To copy a file from one diskette to the other, try

COPY "name:D700" TO ":D701"

note that if the source diskette has volume name label1 you can also use:

COPY "name.label1" TO ":D701"

To copy ALL files use:

COPY ":D700" TO ":D701"



Thanks for the guidance. I tried blocking the rectangular hole opposite the no overwrite hole on the 3 1/2 inch floppy disc but it still gave the disc error message-also tried the initialize command with same result. I guess the best answer is to go to the want ad section and see if anyone can supply what I believe is a single density, single sided 3 1/2 inch floppy.


Actually, it's double density, and double sided is OK and probably all you'll find. www.microcenter.com, which a couple of months ago only offered a bulk package of 500 DSDD diskettes for $50, no longer has that offer but now has a couple of 10 packs of Imation brand pre-formatted (Mac 800K, PC 720K) DSDD diskettes for $3.99.

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