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PET 8032 with 64K mem expansion
  by Bill Degnan - 10/25/2009 07:21
The Commodore PET 8032. This unit has the 64K Memory Expansion Installed.


Because I don't have a working PET 4032 motherboard I decided to install a PET 64K memory expansion kits in one of my 8032's instead. The memory expansion board consists of 32 4116 chips. The Motherboard's 6502 is moved to the memory board.

I have two PET 8032's - SN 01026512 (works, has a missing 4 key) and SN 01026512 (works, brand new keyboard, 2 Amp fuse mod). I chose the latter for the 64K upgrade because it was in better shape.

The physical installation went just fine, the kit had all of the parts. A problem arose when I applied power - the large voltage regulator on the memory board started to smoke and I was forced to quickly power off the system. I removed the board.

64K Memory Expansion Kit, L7805 CT is bad, needs to be replaced.


Fortunately I found another used but working 64K memory expansion board and I installed that one instead. The kit includes a BASIC wedge diskette (one disk each for 4040 and 8050 drives) with routines that can be used to tell the 8032 of the extra 64K of available memory, and makes it available for BASIC programs to use.

INSTALLATION INSTRUCTIONS:
Diagram

1. Remove the 6502 from the motherboard and install into the memory board in the open slot in the middle of the board. 6502 installed on the memory board.

2. Attach the flat cable to the motherboard in the just vacated CPU slot so that the cable lays towards the front of the computer

3. Attach the two power connectors to the motherboard using the plugs to guide you which are the correct ones. The long cable connects to the power connector near the back left of the motherboard on one end and the power connector in the front of the memory board next to the flat cable connector.

4. The short power cable connects to the power connector on the middle left of the motherboard near (C16 and C64) and the left-most power connector on the front of the memory board.

Image of memory board front on, with 2 power connectors and flat cable installed.

5. There are 2 short risers and 2 long risers that are used to position the memory board above the motherboard. Install the risers and position the board so you can still close the chassis. You may have little tightener screws inside of your risers to keep the board secure.

Commodore PET 8032 with chassis opened and revealing the 64K memory expansion board installed. This system has 96K available for programs. Click for larger image.



Note: I sell these memory expansion kits on my web site, I have one left. Although they're "new" anything from 1980 is suspect and should be carefully powered and tested before production use. I will be willing to test a board before selling if I have time.


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