I had a badly deteriorated industrial computer chassis with accommodation for 2x 8” drives. It also had a cutout for two 5.25” floppy drives. I could have used it on an STD project, but I have another rack that I can use for that which is more compact and has an integrated power supply.
I figured that if i reduced the length of the chassis to get rid of some bulk, then it might make a good drive unit for the Cromix system above.
It took a lot of mechanical work, but the result worked pretty well. I put a window in the top cover just so that the operations of the 8″ drives could be seen and enjoyed – not something i would have done with a vintage unit.
I added one more high density drive (Mitsubishi 4854) which is on the 5.25” cable but appears to the cromix to be another 8” drive. I had to make a small mod to the 16FDC board to route the pin 34 of the 5.25” interface (RDY) to pin 22 of the 8” drive interface. This is because the high density 5.25” inch is treated as an 8” drive and Cromix expects a ready signal for those drives.
This particular Mitsubishi 4854 drive has a curious property whereby the reduced write current pin 2 has been disconnected – possibly because it was in a system which used pin 34 for a drive or side select. The line is pulled up, but only when the terminator is in place. That means this drive must carry the terminator because the line does have to be high.
Along the way I checked the alignment of the drive (which was good) but noticed that imagedisk could only make sense of the very first track on side 0. Apparently this track is FM rather than MFM – probably for compatibility with the 16FDC ROM.
The Mitsubishi M4854 drive has a head solenoid. The solenoid is probably unnecessary because the system seems to be ok with the drive spinning up on each access (this didn’t work with other high density drives or the 8″ drives).
Currently, i use a gotek/flashfloppy in place of the 40 track 5.25″ boot drive. I start with an image of a 40 track boot disk and can then switch to any of the myriad of 8″ disk images from the GIT repository.
Drives/devices are arranged as follows:
| Drive | Mount Point | Small | Large | Uniform Small | Uniform Large | |
| 0 | Gotek | da | sfda | fda | usfda | ufda |
| 1 | 8” | db | sfdb | fdb | usfdb | ufdb |
| 2 | 8” | dc | sfdc | fdc | usfdc | ufdc |
| 3 | 5.25 80 Track | dd | sfdd | fdd | usfdd | ufdd |
I also expect to be able to use this unit with the Compupro/Jade CP/M machine.
