TI-99/4A Side Port

Available on TI-99/4A computers. On the right side

  2                    44
+----------------------------------+
| ================================ |
+----------------------------------+
  1                    43

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

Contributor:

Joakim Ögren

Source: