9121 discs


How does one get a modern 3.5" fd to work in an old 9121 drive? Are there some holes that need to be taped up?


> How does one get a modern 3.5" fd to work in an old 9121 drive? 
> Are there some holes that need to be taped up?

Yes and no. The quad density floppies (i.e. PC floppies) are not really suitable for double density drives (9121). However, for casual use (i.e. not backup) they, more or less, work.

You just tape the quad density hole (the square hole opposite the WRITE PROTECT slider).



so, what sources for double density disks?


> so, what sources for double density disks?




MEI Microcenter used to specialize in bulk diskettes, now they have a much bigger selection of other things but they still have a 10-pack of DSDD 3.5 diskettes for $3.99:


You can also get there by going to www.mei-microcenter.com (printed on their paper catalog).

There is another factor that applies to the 9121, which was discovered by Mike a while back - and which I verified from the 9121 manuals and some old diskettes I have. The first units couldn't open the sliding cover on today's diskettes. HP's first single sided diskettes have a different cover which is not spring loaded and has to be opened by hand, there is a friction catch at either extreme that holds the cover open or closed. You have to open the cover before inserting the diskette and then close it after you remove the diskette. Then HP came out with "auto shutter" single sided diskettes that are spring loaded but have a hook catch that holds the cover open; you have to squeeze the corner to release the catch and close the cover. These work manually in the early drives and automatically in later drives. The 9122, which is like a 9121 with double sided drives, uses diskettes just like today's 720K PC (800K Mac) diskettes.

I have two manuals, a 9121 and a 9121/9122. The 9121 manual describes how to use the manual shutter diskettes, then describes the auto shutter diskettes and says: "Remember, either type of disc (manual or auto shutter) will work in either type of drive. If you do not have the auto shutter mechanism in the drive and the disc, you must follow the procedure described with using the manual shutter." The 9121/9122 manual has a media compatibility chart that has an asterisk next to the "OK" for using double sided media in a 9121, which says: "If you have to manually open the shutter on a disc before inserting the disc into the HP 9121, you cannot use double-sided media." These are the only mentions in these manuals about two different versions of disk drive mechanism.

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