S100 Computers

Home S-100 Boards History New Boards Software Boards For Sale
Forum Other Web Sites News Index    
The MPU-B  was a follow-on to their original 8080 MPU Board.


The MPU-8 was an S100 Bus board based on the 8085 microprocessor.  It contained:-
A 1K program PROM/ROM
1 to 4K of RAM
A power on jump circuit
Serial I/O
Parallel I/O
5-levels of interrupts  

The 1K byte PROM/ROM socket was provided with jumpers to configure it for 1K or 2K byte PROMs (or 1K, 2K, or 4K byte of custom ROMs). A 1K ROM was included with the basic system support firmware. Under software control, the ROM could be located at 0000, or at 0800H.  Power on clear initialized the ROM at 0000 to serve as a power on jump. The processor could write to the RAM at 0C00H even when executing code in the ROM at 0000H.  A custom programmed PROM at this location could initialize the system, load programs into the entire 65K memory space, and then disable the PROM while jumping to the program start location.  The PROM could be re-enabled at any time to use code stored in it, either at location 0000 or at location D800H.  The PROM enable was delayed to permit a jump or call to a routine even from a program executing directly underneath the PROM location, A system reset automatically re-enabled the PROM at 0000H.
The manual for this board can be seen here. The schematic can be found here.

Other IMSAI S-100 Boards

4KRAM   8080CPU   EPROM-Programmer    MPU-B   PIC-8   PIO   PROM-4   SIO   VIO  MIO



This page was last modified on 10/25/2013