Available on TI-99/4A computers. On the right side
| Pin |
Name |
Dir |
Description |
| 1 |
VCC |
- |
+5 Volts power supply |
| 2 |
SBE |
OUT |
Low if addr in >9000-94xx (sound port) |
| 3 |
RESET* |
OUT |
System reset (active low) |
| 4 |
EXTINT* |
IN |
External interrupt (active low) |
| 5 |
A5 |
OUT |
Address bus, bit 5 |
| 6 |
A10 |
OUT |
- |
| 7 |
A4 |
OUT |
- |
| 8 |
A11 |
OUT |
- |
| 9 |
DBIN |
OUT |
Active high = read memory |
| 10 |
A3 |
OUT |
- |
| 11 |
A12 |
OUT |
- |
| 12 |
READY |
IN |
Active high = memory is ready |
| 13 |
LOAD* |
IN |
Unmaskable interrupt (=> BLWP @>FFFC) |
| 14 |
A8 |
OUT |
- |
| 15 |
A13 |
OUT |
- |
| 16 |
A14 |
OUT |
- |
| 17 |
A7 |
OUT |
- |
| 18 |
A9 |
OUT |
- |
| 19 |
A15 |
OUT |
Address bus, lsb. Also CRU output bit. |
| 20 |
A2 |
OUT |
- |
| 21 |
GND |
- |
Ground |
| 22 |
CRUCLK* |
OUT |
Inversion of TMS9900 CRUCLOCK pin |
| 23 |
GND |
- |
Ground |
| 24 |
PHI3* |
OUT |
Inversion of phase 3 clock |
| 25 |
GND |
- |
Ground |
| 26 |
WE* |
OUT |
Write Enable (derived from TMS9900 WE* pin) |
| 27 |
GND |
- |
Ground |
| 28 |
MBE* |
OUT |
Active low if addr in >4000-5FFF (card ROMs) |
| 29 |
A6 |
OUT |
- |
| 30 |
A1 |
OUT |
- |
| 31 |
A0 |
OUT |
Address bus, bit 0 (most significant) |
| 32 |
MEMEN* |
OUT |
Memory access enable (active low) |
| 33 |
CRUIN |
IN |
CRU input bit to TMS9900 |
| 34 |
D7 |
IN/OUT |
Data bus, bit 7 (least significant) |
| 35 |
D4 |
IN/OUT |
- |
| 36 |
D6 |
IN/OUT |
- |
| 37 |
D0 |
IN/OUT |
Data bus, bit 0 (most significant) |
| 38 |
D5 |
IN/OUT |
- |
| 39 |
D2 |
IN/OUT |
- |
| 40 |
D1 |
IN/OUT |
- |
| 41 |
IAQ |
IN |
Interrupt acknowledged by TMS9900 |
| 42 |
D3 |
IN/OUT |
- |
| 43 |
VDD |
- |
-5 Volts power supply |
| 44 |
AUDIOIN |
IN |
To sound generator AUDIO IN pin |