ZX80The ZX 80 was brought to the market by Science of Cambridge LTD later known as Sinclair Research way back in 1980. It was the first home computer which costs less than 100 GBP as a kit form and assembled for 129GBP. Although other machines were available in the UK and US market such as the MK14, it was considered as the first computer for the masses.
The internal was designed by Jim Westwood around a Z80 CPU with a clock speed of 3.25Mhz, 1K Ram and 4Kb ROM. The good thing about the ZX80 is that its logic was not designed on custom chip but using TTL chips readily available from most electronic shops. The ROM contained Sinclair Basic programming language, editor and operating system.

The Case was designed by Rick Dickinson and since no ventilation is present there is a durability problem due to overheating. Video was generated via an RF modulator, TTL Chips and software inside the ROM. This was an idea by Don Lancaster in 1978. As a result of this the ZX80 could only generate a display when the CPU is idle. Another issue was RAM as the display was stored in the available 1K limited the user to less memory and to display a full page the user was then limited to only 380 bytes of ram. Fortunately one could use the expansion port for additional ram capable of an extra 16K and other peripherals such as printers, drives and modems.
The difference in the UK and USA version was very minimal, the US version had a better shielding inside for RF, different keyboard symbols wording such as the enter key, ROM, RF Modulator for NTSC and Power Supply. The rest was identical to the UK version make it very simple to interchange between UK and USA version.

ZX 80
KIT £75.95 (UK) $96.99 (US)
ASS £99.95 (UK) $127.99 (US)
N/A due that its a kit
Zilog Z80 CPU running at a Frequency of 3,5 Mhz.
4 Kbytes Rom and 1 Kbytes of RamExpandable to 16K ram with rampack.
Very Small white plastic case with blue keys on a black membrane keyboard for low cost production. The Sinclair Logo is embossed on the far end of the case, and a ZX80 Logo above the keyboard in orange. On the left side there are the connections for the Tape and power sockets. While the bus expansion port is located at the back of the machine. The Keyboard membrane is a 40 key non standard QWERTY style with all the keys the same size. The keys have 5 different functions which represents a basic command for faster programming.
The Display is entirely handled by the CPU in it’s limited spare time.
On text mode it can display a resolution of 32×22′ and in Graphics mode 64×44.
Only fast mode available and no colour (B&W).
No Sound
1 x Phono RF Connector.
2 x 3.5mm Mono Jack one for Save and the other to load from a normal cassette recorder.
1 x Edge Connector for upgrading memory, graphics and sound.
The power supply of the ZX80 is a common 9V DC 700mA. The only problem that was encountered with this type of power supply is that when you upgrade the machine, you had to change the power supply with a higher wattage rating.
Dimensions 174mm x 216mm x 36mm (W x L x H) Weight Approx 300g.
More or less 100,000 units sold in Europe and USA.

The Club currently owns 2 versions the UK and the US version. The UK version is in fully working state, boxed and complete with manuals, cables and power supply. The US version is without manuals and box but fully working state. The two versions are in very good state and clean from any scratches or wear.



3.5mm JackFemale at the Computer

Pin Name Dir Desc
2 GND N/A Ground


Expansion Port

46 Pin EDGE Connector
at computer
side Key way is Ref

Pin Name Dir Desc
1 +5V OUT +5V DC
2 +9V OUT +9V DC
3 KEY WAY N/A Seperator
4 0V N/A Ground
5 0V N/A Ground
6 /0 OUT Clock
7 A0 OUT Address 0
8 A1 OUT Address 1
9 A2 OUT Address 2
10 A3 OUT Address 3
11 A15 OUT Address 15
12 A14 OUT Address 14
13 A13 OUT Address 13
14 A12 OUT Address 12
15 A11 OUT Address 11
16 A10 OUT Address 10
17 A9 OUT Address 9
18 A8 OUT Address 8
19 A7 OUT Address 7
20 A6 OUT Address 6
21 A5 OUT Address 5
22 A4 OUT Address 4
23 N/C N/A Rom Channel Select
A D7 IN/
Data Bit 7
B /RAM CS IN Ram Channel Select
C KEYWAY N/A Seperator
D D0 IN/
Data Bit 0
E D1 IN/
Data Bit 1
F D2 IN/
Data Bit 2
G D6 IN/
Data Bit 6
H D5 IN/
Data Bit 5
I D3 IN/
Data Bit 3
J D4 IN/
Data Bit 4
K /INT IN Interrupt Request
L /NMI IN Non Maskable Intr
M /HALT IN Request Port
N /MREQ IN Memory Request
O /IORQ IN IO Request
P /RD IN Read
Q /WR IN Write
R /BUSAK IN Bus Aknowledge
T /BUSRQ IN Bus Request
V /MI IN Memory Interrupt
W /RFSH IN Refresh



3.5mm JackFemale
at the Computer

Pin Name Dir Desc
2 GND N/A Ground



35mm JackFemale at the Computer

Pin Name Dir Desc
1 +9V IN +9C DC
2 GND N/A Ground



Phono Jack
at the Computer

Pin Name Dir Desc
2 GND N/A Ground