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 $B000 (SYS 45056).
My PET 2001-32 have the ROM of BASIC 4.0 and the UD5 socket where the DiskMON ROM is installed is already used by one of the BASIC 4.0 ROMs, to test the i had to program the EPROMs with BASIC 2.0. (see photo)
Also before testing the interface i had to replace almost all the tantalum capacitors because many were short-circuited.
Capacitors replaced:
- 6 x 10uF/25v
- 1 x 1.5uF/50v
- 2 x 1uF/35v
Below a video and some photos documenting the full working operation.
Gallery:
Download:
Video:
Commodore CBM 8032 (HP – Early version 1980) – CompuThink Disk Drive Controller – External Dual Disk Drive – Woltron ROM-BUS Adapter.
- COMPU/THINK (CompuThink) Dual Disk Drive Controller with 8k RAM per commodore PET 8032 (It could be a Prototype or a Clone Board with ASSY 001-35 – DD DSK CTL COMP).
- COMPU/THINK External Dual Disk Drive 800k DD/DS.
- WOLTRON ROM (CompuThink C-DOS & TOOLKit) + PET/CBM Expansion BUS Adapter + PIA (Peripheral Interface Adapter) Motorola MC6821.
Unfortunately there is no documentation on the net of this Computhink card that seems to be a prototype or a clone, also there is no documentation or photos of the BUS/ROM Adapter by Woltron.
I spent sleepless nights looking for the starting SYS for the disk management software on the eprom, i have disassembled 24k of code (C-DOS Roms / Basic Roms Patched / Edit Roms Patched) in machine language.
I did it and found it the starting sys ($E790 – SYS 59280), although everything seems to work perfectly after the sys command is printed on the screen (*DOS-40*) and by typing the directory command ($d,1) or the format command ($f,1) the floppy starts to run correctly but the head does not move, while the exit command ($h) work correctly,
i need to say that i replaced the FDC1791 and some floppy disk logic and also one floppy disk drive, but nothing changed.
My suspicion falls on the PROM 82S123 there is no dump on the net, reading this PROM of 32 bytes, only the first 8 Bytes are filled, this is right ? we’ll never know.
All EPROM and PROM have been dumped and you can find them in the archive below.
Gallery:
Download: C-DOS 4.0 - Basic/Edit Roms Patched - PROM 82S123 (1019)
Commodore SuperPET (SP9000/MMF9000) Accessories & Motherboard KIT for Replacement (NOS)
This is a New Old Stock (NOS) Kit from Commodore sold as spare parts for the Commodore SuperPET (SP9000/MMF 9000). We are talk about the early model of the SuperPET the one with two internal motherboards (sandwich) and four external switches.
Motherboards and Accessories have never been used, both they are in a perfect state.
The kit includes:
- Accessories KIT (4 switches with Metal Bracket / Power Supply Cables / 20+20 Pin Male IDC Socket + Flat Cable / Eprom Sockets / 6702 Dongle software copy protection Card)
- Commodore BMB Compuscience Ltd Board (ASSY 324035 – REV C)
- Commodore Compu-Think 64K Expansion Ram Board (ASSY 324042)
In the photos you can also see another Commodore BMB Compuscience Ltd Board with the same ASSY but without some eproms. This motherboard is new and never used like the previous one.
With this KIT i can finally complete my Commodore SuperPET without the two motherboards and accessories to get a SuperPET and not a simple Commodore 8032 with a SuperPET label ;-)
Gallery:
Autopsy:
The Expandamem of CompuThink (Compu/Think) is a Memory expansion card for Commodore PET (chicklet keyboard) and KIM-1.
The memory expansion was installed inside the Computer Commodore PET and with a particular hook was fixed above the motherboard. The connection was through the expansion bus and a power connector.
Download: CompuThink Memory Expansion Manual (1662)
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