On Thu, Apr 29, 2010 at 8:53 AM, Anders Carlsson <email@example.com> wrote: > I duplicated the five images here: > http://www.geting.se/viewimage.php?image=238902-P1030084a.jpg > http://www.geting.se/viewimage.php?image=238903-P1030085a.jpg > http://www.geting.se/viewimage.php?image=238904-P1030086a.jpg > http://www.geting.se/viewimage.php?image=238905-P1030087a.jpg > http://www.geting.se/viewimage.php?image=238906-P1030088a.jpg > > Somehow, I'm sure Ruud has seen those before... :-) I have a couple of those myself. I've reverse-engineered the PCB inside to about 95% (I think there are one or two signals I need to check before I call it complete). Essentially, these boxes have a local ROM that overrides the motherboard ROMs (I think the circuit forces the bus to read ROM addressed at $9xxx rather than $fxxx to capture the normal 6502 reset vector transaction). To diagnose your PET, you typically plug loopback connectors onto the user port and the keyboard connector... http://zimmers.net/anonftp/pub/cbm/schematics/computers/pet/diagnostics.txt ...and clip the box on the CPU, then power on the machine. Here's a scan of the manual... http://www.commodore.ca/manuals/Testing_The_PET/testing_the_pet_computer.htm (I think I have a copy of the tape mentioned in the manual - I'll check my PET documentation shelf). AFAIK, there is no substantial difference between the various "models" of clip, just different firmware (there might be a 2K vs 4K variety, though). I also have a few ROM images for 60Hz machines. We should create a new section on zimmers.net to collect these files. Reproducing these boxes would not be difficult at all - the only expensive part would be the 40-pin gompers clip. -ethan Message was sent through the cbm-hackers mailing listReceived on 2010-04-29 15:00:10
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