ZMJC Computer: Difference between revisions

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

CON1: ADC Input / DAC Output
Pin	Function	Pin	Function
1a	DAC V_ref	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

CON2: Expansion Bus
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

CON3: RS232 (25 pin D-Type)
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

CON4: Power
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

Main Memory
Start	End	Function
8000H	27FFFH FFFFH 9FFFH	128 KB RAM 32 KB RAM 8 KB RAM
0000H	7FFFH	32 KB ROM

IO Ports
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

@@ Line 17: / Line 17: @@
 Long-term extensions:
 * Expand to 1 MB RAM
-* Add sound, eg [https://en.wikipedia.org/wiki/Yamaha_Y8950 Y8950]
+* Sound, eg [https://en.wikipedia.org/wiki/Yamaha_Y8950 Y8950]
 * Voice synthesiser, eg [https://en.wikipedia.org/wiki/Texas_Instruments_LPC_Speech_Chips TMS5220]
-* Add video out, eg [https://en.wikipedia.org/wiki/TMS9918 TMS9918], [https://en.wikipedia.org/wiki/Yamaha_V9938 V9938]
+* Video out, eg [https://en.wikipedia.org/wiki/TMS9918 TMS9918], [https://en.wikipedia.org/wiki/Yamaha_V9938 V9938]
-* Add realtime clock, eg Epson RTC7242
+* Keyboard controller, eg VT8242
-* Storage controller (eg FDD with GM82C765B controller).
+* Realtime clock, eg Epson RTC7242, TI BQ4845 or DS1307
+* Storage controller (eg FDD with GM82C765B or WDC37C65 controller).
+* SPI and/or I2C interface
 == Connectors ==
@@ Line 34: / Line 36: @@
 |1a||DAC V<sub>ref</sub>||1b||DAC Out
 |-
-|2a|| ||2b||
+|2a||Gnd||2b||+5 V DC
 |-
 |3a|| ||3b||
 |-
-|4a|| ||4b||
+|4a||Gnd||4b||Gnd
 |-
 |5a|| ||5b||
@@ Line 44: / Line 46: @@
 |6a|| ||6b||
 |-
-|7a|| ||7b||
+|7a||Gnd ||7b||
 |-
-|8a|| ||8b||
+|8a||+5 V DC||8b||
 |}
@@ Line 150: / Line 152: @@
 |1a||+5 V DC||1a||+5 V DC
 |-
-|2a||0 V||2b||0 V
+|2a||Gnd||2b||Gnd
 |-
 |3a|| ||3b||
@@ Line 156: / Line 158: @@
 |4a|| ||4b||
 |-
-|5a|| ||5b||
+|5a||^RESET||5b||
 |-
 |6a|| ||6b||
@@ Line 162: / Line 164: @@
 |7a|| ||7b||
 |-
-|8a|| ||8b||
+|8a||Gnd||8b||Gnd
 |}