ZMJC Computer
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Introduction
During my MSc in Electrical and Electronic Engineering at The University of Nottingham (1992-3) we used this single board computer for an assembly language programming module. It must have been designed by one of the university staff, but I can't remember 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 6.1440 MHz (12.2880 MHz crystal)
- 256 KB EPROM
- 8 KB RAM (32 KB or 128 KB options)
- 8 bit switch input
- 8 bit LED output
- RS232 option
- ZN559 DAC option
- AD7828 or ACD0809 ADC option
It is intended that this page will ultimately document the schematic and repoducible PCB layout after I have reverse engineered it.
Long-term extensions:
- Expand to 1 MB RAM
- Sound, eg Y8950
- Voice synthesiser, eg TMS5220
- Video out, eg TMS9918, V9938
- Keyboard controller, eg VT8242
- Realtime clock, eg Epson RTC7242 or TI BQ4845
- Storage controller (eg FDD with GM82C765B controller).
Connectors
Pin | Function | Pin | Function |
---|---|---|---|
1a | DAC Vref | 1b | DAC Out |
2a | Gnd | 2b | +5 V DC |
3a | 3b | ||
4a | Gnd | 4b | Gnd |
5a | 5b | ||
6a | 6b | ||
7a | Gnd | 7b | |
8a | +5 V DC | 8b |
Pin | Function | Pin | Function |
---|---|---|---|
1a | 1b | ||
2a | 2b | ||
3a | 3b | ||
4a | 4b | ||
5a | 5b | ||
6a | 6b | ||
7a | 7b | ||
8a | 8b | ||
9a | 9b | ||
10a | 10b | ||
11a | 11b | ||
12a | 12b | ||
13a | 13b | ||
14a | 14b | ||
15a | 15b | ||
16a | 16b | ||
17a | 17b | ||
18a | 18b | ||
19a | 19b | ||
20a | 20b | ||
21a | 21b | ||
22a | 22b | ||
23a | 23b | ||
24a | 24b | ||
25a | 25b |
Pin | Function | Pin | Function |
---|---|---|---|
1a | 1b | ||
2a | 2b | ||
3a | 3b | ||
4a | 4b | ||
5a | 5b | ||
6a | 6b | ||
7a | 7b | ||
8a | 8b | ||
9a | 9b | ||
10a | 10b | ||
11a | 11b | ||
12a | 12b | ||
13a | 13b |
Pin | Function | Pin | Function |
---|---|---|---|
1a | +5 V DC | 1a | +5 V DC |
2a | Gnd | 2b | Gnd |
3a | 3b | ||
4a | 4b | ||
5a | ^RESET | 5b | |
6a | 6b | ||
7a | 7b | ||
8a | Gnd | 8b | Gnd |
Jumpers:
- RESET: Close to reset
- RAMSIZE: 8 KB or 32 KB/128 KB
Memory Map
Start | End | Function |
---|---|---|
8000H | 27FFFH FFFFH 9FFFH |
128 KB RAM 32 KB RAM 8 KB RAM |
0000H | 7FFFH | 32 KB ROM |
Port | Function |
---|---|
98H | LED Output |
90H | Switch Input |
88H | DAC Output |
87H | ADC Input 8 |
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 |
Z180 Internal IO Ports: 00 - 3FH
Circuit Description
Software
TBC