ZMJC Computer

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.

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.

CON1: ADC/DAC

Pin	Function	Pin	Function
1a		1b
2a		2b
3a		3b
4a		4b
5a		5b
6a		6b
7a		7b
8a		8b

CON3 (RS232)

CON4: Power

Pin	Function	Pin	Function
1	+5 V DC	a	+5 V DC
2	0 V	b	0 V
3		c
4		d
5		e
6		f
7		g
8		h

Jumpers:

• RESET: Closes to reset
• RAMSIZE: 8 HB or 32 KB/128 KB

Memory Map

Main Memory

Start	End	Function
8000H		RAM
0000H	7FFFH	ROM

IO Ports

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