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Cromemco DPU Board
This was a unique board. It's the only case I know of a Z80 and 68000 CPU chip on the one S-100 board.  It was an extremely useful and powerful board.  Today it is quite a rare board.  It was used primarily for Cromemco's "Cromex Operating System".
 DPU Board 
The Cromemco 68000 board family is comprised of the DPD Dual Processor Unit, MCU Memory Control Unit, and 256MSU and  512HS0 Memory Storage Units.

Based on the Motorola MC68000 microprocessor chip, the Cromemco DPU introduced 32-bit computing speed and power to the Cromemco line of computers. The DPU is a Dual Processor Unit, also incorporated an 8-bit Z-80A microprocessor chip to ensure compatibility with existing software. Microprocessor selection is under software control, allowing the programmer to select the chip of choice for any particular application or routine. An existing Z-80 program, for example, could be run on the DPU with a subroutine or two rewritten in 68000 code to speed things up. Appendix A of the manual (see below) contained a Z-80 Assembly language program which demonstrated the use of software controlled microprocessor switching techniques.

And what about that program which doesn't quite all fit in main memory? With a 24-bit wide address bus, the MC68000 can address up to 16 Mbytes of memory. This is not bank-selected memory. The MC68000 could directly address 16 megabytes of RAM.

The Cromemco HCU Memory Controller Unit acted as an interface between the S-100/IEEE-696 bus and the Cromemco M bus which runs between the MCU and its associated MSUs. A single MCU worked in conjunction with up to eight MSU boards providing not only an interface, but an error detection, correction, and logging system. The Cromemco 256MSO provided 128K 22-bit words, each of which includes six bits for error detection and correction. The 512MSO provided 256K 22-bit words. This scheme allowed all single-bit errors to be corrected and logged.  The Cromemco 68000 board family conforms to the S-100/IEEE-696 bus standard.
The Cromemco rather short manual for this board can be obtained here
.   The schematic can be obtained here.


Other Cromemco S-100 Boards
ZPU  SBC   4KRAM  16K RAM  64KZ RAM  64KZ-II RAM  256KRAM  8KBytesaver  Bytesaver-II  
16KPROM  32K Bytesaver  4FDC   16FDC  64FDC  WDI  WDI-II   STDC  DPU
4PIO   8PIO   TU-ART  D+7A I/O   Dazzler  PRI   GPIB Board   XMU  XXU  Other Boards


This page was last modified on 10/25/2013