Electronics > Projects, Designs, and Technical Stuff

Cloning a Commodore PET-2001

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GK:

--- Quote from: chickenHeadKnob on July 16, 2017, 05:45:52 am ---
--- Quote from: GK on July 16, 2017, 04:12:05 am ---OMG! The "MBL8088-2" (center-bottom) is an 8 MHz version of the classic Intel MPU as used in the 1st IBM PC. This might be the perfect part for an Altair work-alike on steroids.

--- End quote ---
Get an xt motherboard and a NEC v20 chip instead and be able to run both MS-dos and CPM.  For a brief time I had to use such a machine to support legacy CPM based software. It ran seamlessly, a bit better than a real z80/8080 machine.

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Problem with MS-DOS / CP/M is that they're not very functional without a disk drive of some description. An emulator based on compact flash storage would work I guess, but I'm not exactly there yet. A Z84 MPU and an associated bunch of bits currently sits on the shelf for the TRS-80 clone for which I'm still working out the details, to happen once the PET is out of the way. Best not get too far ahead of myself I suppose.... Also, although I can't quite put my finger on exactly why, the advent of MS-DOS marks a time in the evolution of vintage computing where my interest in the old technology suddenly takes a nosedive.

CJay:

--- Quote from: GK on July 16, 2017, 02:28:34 am ---I think I'm getting the old-school computer bug. Sifted through my stash of DIP pulls from salvaged digital (computer, etc) boards this morning. Do I have anything particularly exciting here?



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*eyes you with suspicion* Have you been going through my stash?

GK:
Ha ha, you might be missing a keyboard or two if that was the case.

@rt:

--- Quote from: GK on July 15, 2017, 07:26:22 am ---Apparently not a lot of enthusiasm around here for cloning old computers like the PET? I though being a traditional hardware/discrete logic implementation rather than another boring FPGA port that this would garner more interest.

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Not replying doesn’t mean not watching ;)

Just that I don’t have anything to add, other than when I had a 1084S, not only was the front cover intact, but I also had a spare!  :D

GK:
OK, with a bit of perseverance I got the lowly PIC16F874 that I had handy to successfully interface the keyboard (running at 4 MIPS). Haven't examined the timing headroom or have tried to optimise the code enough to work in turbo mode yet; have just been working to iron out all of the intricacies of the PS/2 keyboard standard - and what a hodgepodge of a standard it is too. Once the code is finalised I can port it to a faster microcontroller easily enough if necessary.

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