IMSAI - MPU-B Board
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
Timers
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
FDC (FIB/FIM)
This page was last modified
on
10/25/2013