HP 9122C Dual 1.44MB Floppy Drive

High Density 3.5" floppy drive using HP-IB interface to connect to HP computers. This drive uses HP's CS80 protocol for communicating with the computer.

Setup Notes
To get the most out of one of these with a Series 200 computer you will need a HP 98625 Disc Interface and HP 98620A DMA Controller which extend the system hardware to allow for faster access and booting from CS80 drives like this.

Floppy Disk Drives
The internal drives of my 9122C were Sony MP-F37W-50 drives. These drives have switches on the side for setting a drive ID rather than using a twist in the cable. This also means both drives spin whenever accessing either one.

These drives are also powered through the ribbon cable. This makes them incompatible with other systems and not easy to replace with other drives.

Disk Formats
There are a large number of disk formats supported by this drive. Shown are the default formats for High and Low Density disks. They use 77 tracks with 256 bytes per sector, but low density disks are 16 sectors while high density are 32 sectors. Note that both formats also create a 78th formatted track at track 79, the purpose of this track is not yet known but may be related to booting the disk.

To decode flux data from a raw image of a 9122C disk, you can use the following Greaseweazle (archived) diskdefs to properly decode DD and HD images disk hp.lif.80dd cyls = 77 heads = 2 tracks * ibm.mfm interleave = 2 secs = 16 bps = 256 end end disk hp.lif.80hd cyls = 77 heads = 2 tracks * ibm.mfm interleave = 2 secs = 32 bps = 256 end end

2023-06

 * Internal Sony floppy drives were stuck do to grease sticking
 * Drive disassembled and cleaned to make work

Related Devices

 * HP 9836C
 * HP 98625 Disc Interface