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CompuPro - 68000 CPU
This is a difficult CompuPro (actually Viasyn) board to now find. It was used for the development of CPM-68K software when it was thought that that was the direction future microcomputer software was going to go in the early 80's.  Clearly it did not happen.  Nevertheless the board is quite something and worth maintaining.  The board was introduced in April 1983.


The board normally ran with an 8 MHZ clock with some 10 MHZ versions. (Remember the clock in 6800x chips was ~2X the Intel chips). The two empty sockets could accommodate 2716, 2732 or 2764 EPROMS in a high/low byte arrangement.

The challenge for Motorola CPU's was there was no separate I/O signals. CompuPro mapped the 256 I/O ports to addresses FF0000H to FFFFFFH. Only the lower 8 bits were normally used.   One unusual thing about the board was CompuPro allowed the S-100 master clock signal (#24) to be disabled by a signal on pin 21. This allowed slower slave processors to run on the bus at a lower speed.  The board also allowed up to 5 wait states be put on the bus.

The 68000 had a built in seven level priority interrupt structure this made splicing it to an external interrupt controller on the bus a little tricky. CompuPro provided a few options on this board.  There was a large empty socket in the center of the board that was used to add an optional 68451 memory management chip.

Apparently when Compupro was manufacturing it's CPU-68K S-100 processor board. Bill Godbout never stopped grumbling about Motorola needing to get their act together.  Revision 184D was the first working production version of the CPU-68K.  Compupro revised the CPU-68K board over and over again to try to get everything working (in particular the MMU).  Compupro laid out the socket for the MMU on the CPU-68K from the very first version of the processor board, and kept revising the board as Motorola kept changing the pin designations or the way that the chips worked.  Motorola eventually stabilized the 68K CPU and MMU designs which allowed Compupro to finally offer the CPU-68K with a working Motorola MMU on version 184F (still needed blue wires), but at least the MMU could be installed, and it would work (crippled). 

Because the boards needed modification to make the MMU work, the socket for the MMU was never supplied on board (unless Compupro installed the MMU),  People who wanted a working MMU would call Compupro for a RMA, and the customer's CPU-68K (acceptable version) would have the MMU socket installed along with necessary modifications to the processor board, and the MMU would be installed and tested.  That way Compupro had control over the way the boards were modified, and the boards with MMU chips installed would all work. (Thanks Michael Louie for this history info).

The schematic for this board can be obtained here.  The technical manual can be obtained here.


Other CompuPro S-100 Boards
CPU8085-88  CPU86-87  CPU-Z  Disk1  Disk1A  Disk1B  Disk2  Disk3   EconoROM2708  Interfacer 1  
RAM Boards   Interfacer 3  Interfacer 4   Interfacer II   M-Drive  MPX-Board  PC-Video  
System-Support1  System-Support2   SPIO  Spectrum  SP186   CPU-286
   68000  32016  SPUZ


This page was last modified on 09/20/2017