Home Computer - Lerncomputer ZX81

Sinclair Radionics Ltd.; St. Ives (Cambridge)

  • Anno
  • 1981–1984
  • Categoria
  • Elaborazione di segnali e strumenti di calcolo (Computer e moduli SP)
  • Radiomuseum.org ID
  • 361060

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 Specifiche tecniche

  • Numero di transistor
  • A semiconduttori.
  • Gamme d'onda
  • - senza
  • Tensioni di funzionamento
  • Fornita mediante altra unità o unità principale. / DC 9 Volt
  • Altoparlante
  • - Per cuffie o amplificatori esterni
  • Materiali
  • Plastica (non bachelite o catalina)
  • Radiomuseum.org
  • Modello: Home Computer - Lerncomputer ZX81 - Sinclair Radionics Ltd.; St.
  • Forma
  • Tascabile (portatile molto piccola), < 20 cm
  • Dimensioni (LxAxP)
  • 167 x 167 x 40 mm / 6.6 x 6.6 x 1.6 inch
  • Annotazioni
  • The Sinclair ZX81, launched in March 1981, transformed home computing as an affordable, mass-produced device designed by Sinclair Research and manufactured by Timex in Scotland. Priced at £49.95 (kit) or £69.95 (preassembled), it sold over 1.5 million units, becoming the first widely accessible computer in UK high-street stores like W.H. Smith. Its streamlined design used just four chips and 1 KB of RAM (expandable to 16 KB), with a membrane keyboard and TV display. In the U.S., Timex rebranded it as the ZX-81, later releasing upgraded models. The ZX81 catalyzed Britain’s tech industry, fostering a community of enthusiasts and earning its designer, Rick Dickinson, a Design Council award. Its success solidified Sinclair Research’s reputation and contributed to Clive Sinclair’s knighthood.

    Sinclair ZX81 Technical Overview
    Single-board architecture with four primary components: Z80 CPU, ULA2C184E logic chip, 8 KB ROM, and 1 KB RAM.

    Processor

    • CPU: Z80 @ 3.25 MHz (NEC uPD780C variant in some units)
    • Effective speed:
      • SLOW mode (display active): 0.8 MHz (50Hz) / 0.53 MHz (60Hz)
      • FAST mode (display disabled): Full 3.25 MHz

    Memory

    • ROM: 8 KB (BASIC interpreter with floating-point math and 30+ functions)
    • RAM: 1 KB base (expandable to 16 KB via edge connector, third-party expansions up to 64 KB)
      • Note: Timex variants like TS1000 included 2 KB RAM

    Video Output

    • ULA2C184E generates 256×192 pixel output (32×24 characters)
    • RF modulator: UM1233 chip for UHF 625-line TV output
    • Display modes:
      • Text: 32×24 characters (8×8 pixels per char)
      • Block graphics: 64×48 elements (4×4 pixels per block)

    Storage & I/O

    • Cassette interface: 3.5mm jacks for audio storage (300 baud)
    • Expansion port: 44-pin edge connector for RAM/ROM cartridges

    Keyboard

    • Membrane layout: QWERTY with 20 graphic/54 inverse video characters
    • Multi-function keys: 5 roles per key via shift combinations
    • Modern add-ons: ZX-Key interface enables USB/emulator compatibility

    Pricing & Variants

    • US launch: $99.95 (kit) / $149.95 (assembled, Nov 1981)
    • German price: 398 DM assembled
    • Timex models: TS1000 (2 KB RAM), TS1500 (16 KB integrated)

    Operating System

    • Sinclair BASIC: Includes trigonometric functions (8-digit precision) and RND/RAND operators

    Legacy Issues

    • Crash susceptibility: Loose RAM pack connections caused frequent data loss
    • ULA failures: Modern replacements are scarce due to custom chip design

    Note on RAM claims: While some sources mention 2-3 KB configurations, standard UK models shipped with 1 KB. Higher capacities required aftermarket expansions.

  • Peso netto
  • 0.342 kg / 0 lb 12.1 oz (0.753 lb)
  • Prezzo nel primo anno
  • 69.95 £
  • Bibliografia
  • -- Original-techn. papers.
  • Letteratura / Schemi (1)
  • Funkschau (Sonderheft Nr. 08, "ZX81 Kochbuch")
  • Autore
  • Modello inviato da Alfred Klich. Utilizzare "Proponi modifica" per inviare ulteriori dati.

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Il modello Home Computer - Lerncomputer fa parte delle collezioni dei seguenti membri.

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