Sinclair ZX81
 | |
| A fully–assembled Sinclair ZX80 | |
| Specifications | |
|---|---|
| Manufacturer | Science of Cambridge Ltd (later Sinclair Research Ltd) |
| Type | Home computer / hobbyist kit |
| Released | 29 January 1980 |
| Discontinued | March 1981 (superseded by ZX81) |
| Intro price | £79 .95 kit / £99 .95 ready-built (≈US$199/249 in 1980) |
| CPU | Zilog Z80A-compatible (NEC µPD780C-1) @ 3.25 MHz |
| Memory | 1 KB static RAM on-board (expandable to 16 KB, 48 KB with mods) |
| Storage | External cassette tape (300 baud, EAR/MIC jacks) |
| Display | Monochrome RF to TV – 32 × 24 text or 64 × 48 block-graphics |
| Sound | None (no audio hardware) |
| Dimensions | 195 mm × 175 mm × 50 mm (7.7 ″ × 6.9 ″ × 2.0 ″) |
| Weight | ≈ 340 g (0.75 lb) |
| OS / Firmware | 4 KB Sinclair Integer BASIC in ROM |
| Predecessor | Science of Cambridge MK14 |
| Successor | Sinclair ZX81 |
| Codename | “ZX80 project” |
| Model no. | ZX80 |
```markdown
| |
| A fully–assembled Sinclair ZX80 | |
| Specifications | |
|---|---|
| Manufacturer | Science of Cambridge Ltd (later Sinclair Research Ltd) |
| Type | Home computer / hobbyist kit |
| Released | 29 January 1980 |
| Discontinued | March 1981 (superseded by ZX81) |
| Intro price | £79 .95 kit / £99 .95 ready-built (≈US$199/249 in 1980) |
| CPU | Zilog Z80A-compatible (NEC µPD780C-1) @ 3.25 MHz |
| Memory | 1 KB static RAM on-board (expandable to 16 KB, 48 KB with mods) |
| Storage | External cassette tape (300 baud, EAR/MIC jacks) |
| Display | Monochrome RF to TV – 32 × 24 text or 64 × 48 block-graphics |
| Sound | None (no audio hardware) |
| Dimensions | 195 mm × 175 mm × 50 mm (7.7 ″ × 6.9 ″ × 2.0 ″) |
| Weight | ≈ 340 g (0.75 lb) |
| OS / Firmware | 4 KB Sinclair Integer BASIC in ROM |
| Predecessor | Science of Cambridge MK14 |
| Successor | Sinclair ZX81 |
| Codename | “ZX80 project” |
| Model no. | ZX80 |
🧠 Architecture
Video generation
💾 Storage
🔌 I/O and Expansion
🔧 Known PCB Revisions & Errata
🛠️ General Maintenance
📜 Schematic & PCB
🔧 Common Modifications
🔢 ROM Keyword Map
🔗 Edge-Connector Pin-out
🗺️ Exact Memory Map & Key ROM Entry Points
Popular ROM Vectors (ROM v1.2, 1980)
📺 Video Timing Characteristics
🎬 Trivia / Pop-culture
🗂️ Related Pages
🧠 Architecture and Processor
💾 Memory and Storage
🖥️ Display and Graphics
🔊 Sound Capabilities
🎮 Input/Output and Expansion
🧰 General Maintenance
🧾 PCB Schematics & Service Guide
📷 Motherboard Images
📚 Technical Documentation
📷 Gallery
🧪 Related Pages
General Maintenance
PCB Schematics & Service Manual
Apple Service Manual
Logic Board & Analog Board Schematics
Capacitor Replacement Guide
Retrobrite
Troubleshooting
Technical Details
System Architecture at a Glance
Memory Map (Physical)
ROM Layout (256 KB, v5.0)
ADB & PDS Highlights
Floppy / Mass-Storage
Key I/O ICs
Sound Path
RAM Upgrade Notes
Hardware Easter Egg
```
See Also