| Pin | Name | Direction | Description |
|---|
| | --- | |
| 1 | +8V | --- | +5V 3-T regulator voltage supply (about +8V) |
| | --- | |
| 2 | +8V | --- | +5V 3-T regulator voltage supply (about +8V) |
| | --- | |
| 3 | GND | --- | Ground |
| | --- | |
| 4 | READYA | --- | System ready (10K pull-up to +5V) |
| | --- | |
| 5 | GND | --- | Ground |
| | --- | |
| 6 | RESET* | Output | System reset (active low) |
| | --- | |
| 7 | GND | --- | Ground |
| | --- | |
| 8 | SCLK | --- | System clock (not connected) |
| | --- | |
| 9 | LCP* | --- | CPU indicator 1=TI99 0=2nd generation (not connected) |
| | --- | |
| 10 | AUDIO | Input | Input audio (=AUDIOIN) |
| | --- | |
| 11 | RDBENA* | Input | Active low: enable flex cable data bus drivers (1K pull-up) |
| | --- | |
| 12 | PCBEN | | PCB enable for burn-in (always High) |
| | --- | |
| 13 | HOLD* | | Active low CPU hold request (always High) |
| | --- | |
| 14 | IAQHA | --- | IAQ [or] HOLDA (logical or) |
| | --- | |
| 15 | SENILA* | | Interrupt level A sense enable (always High) |
| | --- | |
| 16 | SENILB* | | Interrupt level B sense enable (always High) |
| | --- | |
| 17 | INTA* | Input | Active low interrupt level A (=EXTINT*) |
| | --- | |
| 18 | LOAD* | --- | Unmaskable interrupt (not connected) |
| | --- | |
| 19 | D7 | --- | Data bit 7 (LSB) |
| | --- | |
| 20 | GND | --- | Ground |
| | --- | |
| 21 | D5 | --- | Data bit 5 |
| | --- | |
| 22 | D6 | --- | Data bit 6 |
| | --- | |
| 23 | D3 | --- | Data bit 3 |
| | --- | |
| 24 | D4 | --- | Data bit 4 |
| | --- | |
| 25 | D1 | --- | Data bit 1 |
| | --- | |
| 26 | D2 | --- | Data bit 2 |
| | --- | |
| 27 | GND | --- | Ground |
| | --- | |
| 28 | D0 | --- | Data bit 0 (MSB) |
| | --- | |
| 29 | A14 | Output | Address bit 14 |
| | --- | |
| 30 | A15 | Output | Address bit 15 (LSB). Also CRU output bit. |
| | --- | |
| 31 | A12 | Output | Address bit 12 |
| | --- | |
| 32 | A13 | Output | Address bit 13 |
| | --- | |
| 33 | A10 | Output | Address bit 10 |
| | --- | |
| 34 | A11 | Output | Address bit 11 |
| | --- | |
| 35 | A8 | Output | Address bit 8 |
| | --- | |
| 36 | A9 | Output | Address bit 9 |
| | --- | |
| 37 | A6 | Output | Address bit 6 |
| | --- | |
| 38 | A7 | Output | Address bit 7 |
| | --- | |
| 39 | A4 | Output | Address bit 4 |
| | --- | |
| 40 | A5 | Output | Address bit 5 |
| | --- | |
| 41 | A2 | Output | Address bit 2 |
| | --- | |
| 42 | A3 | Output | Address bit 3 |
| | --- | |
| 43 | A0 | Output | Address bit 0 (MSB) |
| | --- | |
| 44 | A1 | Output | Address bit 1 |
| | --- | |
| 45 | AMB | | Extra address bit. Always High. |
| | --- | |
| 46 | AMA | | Extra address bit. Always High. |
| | --- | |
| 47 | GND | --- | Ground |
| | --- | |
| 48 | AMC | | Extra address bit. Always High. |
| | --- | |
| 49 | GND | --- | Ground |
| | --- | |
| 50 | CLKOUT* | Output | Inversion of phase 3 clock (=PHI3*) |
| | --- | |
| 51 | CRUCLK* | Output | Inversion of TMS9900 CRUCLOCK pin |
| | --- | |
| 52 | DBIN | Output | Active high = read memory |
| | --- | |
| 53 | GND | --- | Ground |
| | --- | |
| 54 | WE* | Output | Write Enable (derived from TMS9900 WE* pin) |
| | --- | |
| 55 | CRUIN | Input | CRU input bit to TMS9900 |
| | --- | |
| 56 | MEMEN* | Output | Memory access enable (active low) |
| | --- | |
| 57 | -12V | --- | -12 Volts 3-T regulator supply voltage (about -16V) |
| | --- | |
| 58 | -12V | --- | -12 Volts 3-T regulator supply voltage (about -16V) |
| | --- | |
| 59 | +12V | --- | +12 Volts 3-T regulator supply voltage (about +16V) |
| | --- | |
| 60 | +12V | --- | +12 Volts 3-T regulator supply voltage (about +16V) |
Direction is computer relative world.