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.


Nella mia collezione di computer vintage mancavano... dei computer Sinclair. Così, ho deciso di acquistare questo retro computer, insieme all'espansione RAM da 16 kB, nonché insieme ad altri computer nell’estate 2021. Ecco il video del lotto acquistato:
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
E’ possibile emulare il Sinclair ZX-81, su un comune PC Windows, tramite l'emulatore EightyOne, che emula anche altri modelli di Sinclair. In questo modo, è possibile provare ad avviare programmi e giochi, nonché programmare il retro computer, in maniera semplice e comoda… senza nemmeno possedere il 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