TI-99/4A Cartridge Port

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

  2                    36
+----------------------------------+
| ================================ |
+----------------------------------+
  1                    35

Pin	Name	Dir	Description
1	RESET	IN	Resets the system (active high)
2	GND	-	Signal groud
3	D7	IN/OUT	Data bus, bit 7 (least significant)
4	CRUCLK*	OUT	Inversion of TMS9900 CRUCLOCK pin
5	D6	IN/OUT
6	CRUIN	IN	CRU input to TMS9900
7	D5	IN/OUT
8	A15	OUT	Address bus, bit 15 / also CRU output bit
9	D4	IN/OUT
10	A13	OUT
11	D3	IN/OUT
12	A12	OUT
13	D2	IN/OUT
14	A11	OUT
15	D1	IN/OUT
16	A10	OUT
17	D0	IN/OUT	Data bus, bit 0 (most significant)
18	A9	OUT
19	VCC	-	+5 Volts power supply
20	A8	OUT
21	GS*	OUT	Grom select. Active low is addr in >9800-9FFF
22	A7	OUT
23	A14	OUT	Address bus, bit 14. Select mode: low=data / high=addr
24	A3	OUT
25	DBIN	OUT	Active high = read memory
26	A6	OUT
27	GRC	OUT	GROM clock: color burst of VDP 9918A
28	A5	OUT
29	VDD	-	-5 Volts power supply
30	A4	OUT
31	GR	IN	Active high = GROM ready
32	WE*	OUT	Active low = write enable (derived from TMS9900 WE*)
33	VSS	-
34	ROMG*	OUT	Active low if addr in >6000-7FFF
35	GND	-	Ground
36	GND	-	Ground

Contributor:

Joakim Ögren

Source: