Timex Sinclair 1000
The US ZX81: NTSC video, 2K RAM and a channel 2/3 switch.
Open the Timex Sinclair 1000 in Retro Bench- Also
- TS1000 (US ZX81)
- Year
- 1983
- CPU
- Z80A @ 3.25 MHz
- RAM
- 2 KB static (one 24-pin 2K x 8 at IC4)
- ROM
- 8 KB BASIC (same as ZX81)
- Video
- NTSC, 60 Hz, 32 x 24 text, VHF channel 2 or 3
- Sound
- None
- OS
- Sinclair BASIC 8K
Chips
| Chip | Where | Role |
|---|---|---|
| ZX81 ULA 2C184E / 2C210E | IC1 | Video sync, character access, keyboard, tape, NMI, ROM/RAM select |
| Z80A CPU | IC3 | Main CPU (8-bit, 40-DIP) |
| ZX81 8K BASIC ROM (2364 type) | IC2 | BASIC, editor, character set and floating point at $0000-$1FFF |
| 6116 2K x 8 static RAM | IC4 (24-pin 2K x 8; 2016/4016/6116 type) | 2K x 8 static RAM. |
Ports and connectors
- Power in (9V DC IN), 3.5 mm mono jack
- EAR (tape in), 3.5 mm mono jack
- MIC (tape out), 3.5 mm mono jack
- TV RF output, RCA phono (Cinch), VHF
- Rear edge connector (2 x 23), PCB card edge, 23 + 23 contacts, slot at 3
Power rails
| Rail | Expect | Measure at |
|---|---|---|
| Power in | About 9 V DC on load, about 14 V unloaded UNVERIFIED | Power jack tip; rear edge B2 |
| +5 V | +5 V UNVERIFIED | regulator output; Z80A pin 11; ULA pin 40; 6116 pin 24 |
| GND | 0 V UNVERIFIED | Z80A pin 29; ULA pin 34; 6116 pin 12 |
Symptoms
- No picture on a US TV: check ULA
- Rolling or no-sync picture: check ULA
- Crashes or garbage in RAM: check 6116
- Wobbly RAM pack (crashes when touched): check 6116
- Dead keys: check ULA
- No boot, dead screen: check Z80A, ROM