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== Introduction ==
== Introduction ==


During my MSc in 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.
During my [https://www.nottingham.ac.uk/pgstudy/course/taught/electrical-and-electronic-engineering-msc 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:
* [https://en.wikipedia.org/wiki/Zilog_Z180 Z80180] CPU ([https://en.wikipedia.org/wiki/Zilog_Z80 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.
It is intended that this page will ultimately document the schematic and repoducible PCB layout after I have reverse engineered it.


== Connectors, options and Ports ==
Long-term extensions:
* Expand to 1 MB RAM
* Sound, eg [https://en.wikipedia.org/wiki/Yamaha_Y8950 Y8950]
* Voice synthesiser, eg [https://en.wikipedia.org/wiki/Texas_Instruments_LPC_Speech_Chips TMS5220]
* Video out, eg [https://en.wikipedia.org/wiki/TMS9918 TMS9918], [https://en.wikipedia.org/wiki/Yamaha_V9938 V9938]
* Keyboard controller, eg VT8242
* Realtime clock, eg Epson RTC7242, TI BQ4845 or DS1307
* Storage controller (eg FDD with GM82C765B or WDC37C65 controller).
* SPI and/or I2C interface


CON1 provides connection to the ADC and DAC options.
== Connectors ==
 
{| class="wikitable"
!Pin
!Function
!Pin
!Function
|-
|+CON1: ADC Input / DAC Output
|1a||DAC V<sub>ref</sub>||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||
|}


{| class="wikitable"
{| class="wikitable"
Line 14: Line 56:
!Pin
!Pin
!Function
!Function
|-
|+CON2: Expansion Bus
|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||
|}


{| class="wikitable"
!Pin
!Function
!Pin
!Function
|-
|+CON3: RS232 (25 pin D-Type)
|1a|| ||1b||
|-
|2a|| ||2b||
|-
|3a|| ||3b||
|-
|4a|| ||4b||
|-
|5a|| ||5b||
|-
|6a|| ||6b||
|-
|7a|| ||7b||
|-
|8a|| ||8b||
|-
|9a|| ||9b||
|-
|10a|| ||10b||
|-
|11a|| ||11b||
|-
|-
|+CON1: ADC/DAC
|12a|| ||12b||  
|1|| ||a||  
|-
|-
|2|| ||a||  
|13a|| ||13b||  
|-
|-


{| class="wikitable"
!Pin
!Function
!Pin
!Function
|-
|+CON4: Power
|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
|}
|}


=== CON2 (Expansion) ===
Jumpers:
* RESET: Close to reset
* RAMSIZE: 8 KB or 32 KB/128 KB
 
== Memory Map ==
 
{| class="wikitable"
!Start
!End
!Function
|-
|+Main Memory
|-
|8000H||27FFFH<br/>FFFFH<br/>9FFFH||128 KB RAM<br/>32 KB RAM<br/>8 KB RAM
|-
|0000H||7FFFH||32 KB ROM
|-
|}


=== CON3 (RS232) ===
{| class="wikitable"
!Port
!Function
|-
|+IO Ports
|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
|-
|}


=== CON4 (Power) ===
Z180 Internal IO Ports: 00 - 3FH


== Circuit Description ==
== Circuit Description ==
TBC


== Software ==
== Software ==


TBC
TBC

Latest revision as of 10:12, 13 October 2024

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, TI BQ4845 or DS1307
  • Storage controller (eg FDD with GM82C765B or WDC37C65 controller).
  • SPI and/or I2C interface

Connectors

Pin Function Pin Function
CON1: ADC Input / DAC Output
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
CON2: Expansion Bus
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
CON3: RS232 (25 pin D-Type)
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
CON4: Power
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
Main Memory
8000H 27FFFH
FFFFH
9FFFH		 128 KB RAM
32 KB RAM
8 KB RAM
0000H 7FFFH 32 KB ROM
Port Function
IO Ports
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

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