Oddball – Floppy drives

The two drives on the word processor have a 34-pin connector that looks like a Shugart interface. Both have the standard 4 pin power connector with the correct looking wire colours. So perhaps they are PC compatible on some level.

The following jumpers exists:

S0-3 – Drive Select

SS – Not sure

SA – Not sure

Opening up the unit shows a single read/write head so this is a single sided drive, making it somewhat rare. I was only aware of 5.25″ drives as single sided on PCs or for old Atari ST machines that came with single sided units. In fact my first Atari STFM had a single sided drive, that was REALLY annoying. In short order I took a saw to the case and replaced it with a double sided drive… Not pretty but far more useful. For this unit it was for a word processor and if my searching so far:

40 Tracks

Single sided

250K capacity

That COULD be right, it is not clear.


Hooking this up to a PC it was possible to address the drive and get it to spin. Using a standard 34-pin cable with the drive A twist and the drive set to S1 (drive 2) it was possible to get the drive to spin when doing a DIR command from DOS and setting it to 720K 3.5″ in BIOS.

Nothing else was possible. However, setting this to 360K 5.25″ drive in BIOS it was possible to actually format it in DOS:

format a: /F:180 /u

It was also possible to read and write data to the drive, if somewhat unable. At this point it is not clear if this is because of a bad disc or a dodgy format option, after all it was a 5.25″ drive selected.

It could be that a PC with an older drive option in BIOS might be more compatible but it is great to get this working in some form.

Other mentions

Could it be compatible with the Opus drive interface for the ZX Spectrum?

What are your thoughts? What other tests could be done or places in which his pair could be used?

Click for other information about the Oddball PC

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