Timex Sinclair 1500
A ZX81 with 16K on board in a Spectrum-style case.
Open the Timex Sinclair 1500 in Retro Bench- Also
- TS1500 (ZX81 in a Spectrum-style case)
- Year
- 1983
- CPU
- Z80A @ 3.25 MHz
- RAM
- 16 KB on board (eight 4116 DRAM)
- ROM
- 8 KB BASIC (Timex revision of the ZX81 ROM)
- Video
- NTSC, 60 Hz, 32 x 24 text, block graphics
- Sound
- None
- OS
- Sinclair BASIC 8K
Chips
| Chip | Where | Role |
|---|---|---|
| TS1500 gate array (Timex / NCR) | U5 | Video, keyboard, tape and RAM control; takes the place of the ZX81 ULA |
| Z80A CPU | Main CPU (8-bit, 40-DIP) | |
| ZX81 8K BASIC ROM (2364 type) | BASIC, editor, character set and floating point at $0000-$1FFF | |
| 4116 DRAM 16K x 1 | U8-U15 | Dynamic RAM, 16K x 1 (lower 16K on the Spectrum) |
Ports and connectors
- Power in (9V DC), Jack socket (size and polarity not sourced) UNVERIFIED
- EAR (tape in), Jack socket UNVERIFIED
- MIC (tape out), Jack socket UNVERIFIED
- TV RF output, RF socket (type not sourced) UNVERIFIED
- Rear edge connector, PCB card edge UNVERIFIED
Power rails
| Rail | Expect | Measure at |
|---|---|---|
| +5 V | +5 V UNVERIFIED | regulator output; Z80A pin 11; 4116 pin 9 |
| +12 V | About +12 V UNVERIFIED | 4116 pin 8 |
| -5 V | About -5 V UNVERIFIED | 4116 pin 1 |
Symptoms
- Nothing on the TV
- Interference or poor picture
- Will not LOAD
- Locked up, BREAK does nothing
- Crashes with a 16K RAM pack fitted
- Dead: no K cursor with the TV tuned: check ULA, Z80A, 4116