CompuThink Disk Drive 800k + Interface (DD DSK CTL P2) + DiskMON ROM seems to be the FIRST EVER disk drive for the Commodore PET Computers ever made in 1979 in the United States, maybe even before the official CBM 2040 drive launched.

I have also a partially working  “clone” or “prototype” (see photo) of this Disk Drive interface that i have posted on the blog some years ago.

As far as i could understand this interface works only with BASIC 1.0 and BASIC 2.0 because the DiskMON ROM has the starting address $B000 (SYS 45056).

My PET 2001-32 have the ROM of BASIC 4.0 and the UD5 socket where the DiskMON ROM is installed is already used by one of the BASIC 4.0 ROMs, to test the i had to program the EPROMs with BASIC 2.0. (see photo)

Also before testing the interface i had to replace almost all the tantalum capacitors because many were short-circuited.

Capacitors replaced:

• 6 x 10uF/25v
• 1 x 1.5uF/50v
• 2 x 1uF/35v

Below a video and some photos documenting the full working operation.

Gallery:

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Download:

• CompuThink Interface Docs & Roms (567)
• CBM PET Basic2 FULL SET (542)
• CompuThink Interface Internet Photo (562)
• Printout Magazine (First Issue 1979) for PET Users (569)
• CompuThink Interface FULL Docs & Roms by DukeFawks (638)

Video: