ZMJC Computer
Introduction
During my MSc in Electrical and Electronic Engineering at The University of Nottingham (1992-3) we used this single boad computer for an assembly programming module. It must have been designed by one of the university staff, but I don't know who; it is just labelled "© 1991 MJC". Hence, I will refer to this as the zMJC Computer. I lost the schematic many years ago.
Key features:
- Z80180 CPU (z80 compatible) running at 6 MHz
- 256 KB EPROM
- 8, 32 or 128 KB RAM
- RS232
- ZN559 DAC option
- AD7828 OR ACD0809 ADC option
- 8 bit switch input
- 8 bit LED output
It is intended that this page will ultimately document the schematic and repoducible PCB layout after I have reverse engineered it.
Connectors
CON1 provides connection to the ADC and DAC options.
| Pin | Function | Pin | Function |
|---|---|---|---|
| 1a | 1b | ||
| 2a | 2b | ||
| 3a | 3b | ||
| 4a | 4b | ||
| 5a | 5b | ||
| 6a | 6b | ||
| 7a | 7b | ||
| 8a | 8b |
CON2 (Expansion)
CON3 (RS232)
| Pin | Function | Pin | Function |
|---|---|---|---|
| 1a | +5 V DC | 1a | +5 V DC |
| 2a | 0 V | 2b | 0 V |
| 3a | 3b | ||
| 4a | 4b | ||
| 5a | 5b | ||
| 6a | 6b | ||
| 7a | 7b | ||
| 8a | 8b |
Jumpers:
- RESET: Closes to reset
- RAMSIZE: 8 HB or 32 KB/128 KB
Memory Map
| Start | End | Function |
|---|---|---|
| 8000H | RAM | |
| 0000H | 7FFFH | ROM |
| Port | Function |
|---|---|
| 90H | Switch Input |
| 88H | DAC Output |
| 87H | ADC Input |
| 86H | ADC Input 7 |
| 85H | ADC Input 6 |
| 84H | ADC Input 5 |
| 83H | ADC Input 4 |
| 82H | ADC Input 3 |
| 81H | ADC Input 2 |
| 80H | ADC Input 1 |
Circuit Description
TBC
Software
TBC