Pin | Name | Direction | Description |
---|
1 | VCC | --- | +5 Volts power supply |
2 | SBE | Output | Low if addr in >9000-94xx (sound port) |
3 | RESET* | Output | System reset (active low) |
4 | EXTINT* | Input | External interrupt (active low) |
5 | A5 | Output | Address bus, bit 5 |
6 | A10 | Output | - |
7 | A4 | Output | - |
8 | A11 | Output | - |
9 | DBIN | Output | Active high = read memory |
10 | A3 | Output | - |
11 | A12 | Output | - |
12 | READY | Input | Active high = memory is ready |
13 | LOAD* | Input | Unmaskable interrupt (=> BLWP @>FFFC) |
14 | A8 | Output | - |
15 | A13 | Output | - |
16 | A14 | Output | - |
17 | A7 | Output | - |
18 | A9 | Output | - |
19 | A15 | Output | Address bus, lsb. Also CRU output bit. |
20 | A2 | Output | - |
21 | GND | --- | Ground |
22 | CRUCLK* | Output | Inversion of TMS9900 CRUCLOCK pin |
23 | GND | --- | Ground |
24 | PHI3* | Output | Inversion of phase 3 clock |
25 | GND | --- | Ground |
26 | WE* | Output | Write Enable (derived from TMS9900 WE* pin) |
27 | GND | --- | Ground |
28 | MBE* | Output | Active low if addr in >4000-5FFF (card ROMs) |
29 | A6 | Output | - |
30 | A1 | Output | - |
31 | A0 | Output | Address bus, bit 0 (most significant) |
32 | MEMEN* | Output | Memory access enable (active low) |
33 | CRUIN | Input | CRU input bit to TMS9900 |
34 | D7 | Input | Data bus, bit 7 (least significant) |
35 | D4 | Input | - |
36 | D6 | Input | - |
37 | D0 | Input | Data bus, bit 0 (most significant) |
38 | D5 | Input | - |
39 | D2 | Input | - |
40 | D1 | Input | - |
41 | IAQ | Input | Interrupt acknowledged by TMS9900 |
42 | D3 | Input | - |
43 | VDD | --- | -5 Volts power supply |
44 | AUDIOIN | Input | To sound generator AUDIO IN pin |