TI-99/4
Earlier TI-99/4. The TI servicing manual covers it with the 99/4A, but its facts are not captured here yet. Check the board before using the 99/4A notes.
Open the TI-99/4 in Retro Bench- Also
- 99/4
- Year
- 1979
- CPU
- TMS9900 @ 3 MHz
- RAM
- Not captured (verify)
- ROM
- Not captured (verify)
- Video
- TMS9918 (verify)
- Sound
- TMS9919 (verify)
- OS
- TI BASIC (verify)
Chips
| Chip | Where | Role |
|---|---|---|
| TMS9900 16-bit CPU | 16-bit CPU at 3 MHz. Needs -5 V, +5 V and +12 V, plus a 4-phase clock. | |
| TIM9904 (SN74LS362) four-phase clock generator | Makes the four-phase 12 V clock for the 9900 (3 MHz) and the power-on reset. | |
| TMS9918A / TMS9928A / TMS9929A video display processor | Video display processor (VDP) with its own 16 KB DRAM bus. Composite out on 9918A; Y, R-Y, B-Y on 9928A/9929A. | |
| 4116 DRAM 16K x 1 | Dynamic RAM, 16K x 1 (lower 16K on the Spectrum) | |
| TMS9901 programmable systems interface | Keyboard scan, joysticks, cassette, interrupts and interval timer, over the CRU serial bus. | |
| SN76489 / SN94624 (TMS9919) sound generator | Three tone voices and one noise voice, written over an 8-bit data bus. | |
| TMC0430 GROM (graphics ROM) | 6 KB serial ROM for TI BASIC, the title screen and cartridge code. | |
| TMS4732 console ROM (4K x 8) | Console ROM at $0000-$1FFF: two 4 KB chips, one per byte of the 16-bit word. | |
| MCM6810 128 x 8 static RAM | The 256-byte CPU scratchpad at $8300: two chips, one per byte of the word. |