The Sinclair ZX81 was a low-cost home computer manufactured in the United Kingdom by Sinclair Research. Introduced in 1981 as a successor to the Sinclair ZX80, the Sinclair ZX81 was produced until 1984. The computer was sold by mail order, as a mounting kit, but it could also be purchased already assembled.
Missing from my vintage computer collection… were some Sinclair computers. So, I decided to purchase this retro computer, together with the 16 kB RAM expansion, as well as together with other computers in summer 2021. Here is the video of the purchased lot:
Start screen of the Sinclair ZX81
The start screen of the Sinclair ZX 81 is very simple and features a fixed cursor with the letter K. The image is available at the RF output (analog channel 36).
Technical characteristics of the Sinclair ZX81
CPU: NEC μPD780C at 3.25 MHz, compatible with Zilog Z80A
ROM: 8 kB
RAM: 1 kB, expandable up to 64 kB
Video: monochrome, text 32 columns × 24 lines, graphics 64 x 48 pixels
Keyboard: QWERTY 40 keys, membrane
Software included in ROM: Sinclair BASIC
Expansion ports:
- 1 Expansion port
- 1 Antenna (RF connection to TV)
- 2 Cassette recorder ports (out and in)
Dimensions: 16.7 cm (width) x 17.5 cm (depth) x 4 cm (height), 350 g
Emulation
It is possible to emulate the Sinclair ZX-81, on a common Windows PC, through the EightyOne emulator, which also emulates other Sinclair models. In this way, you can try to start programs and games, as well as program the back computer, in a simple and convenient way... without even owning the Sinclair ZX 81!
Power supply
The power supply of the Sinclair ZX81 is external. It generates a single 9 V voltage in direct current, unstabilized, with wide tolerance. The available current is 1.2 A. The connector is a 3.5 mm jack.
Papers
1. Sinclair ZX81 BASIC programming manual
2. Sinclair ZX-81 service and assembly manual
Date of entry into the collection: 08/25/2021