TI-99/4A Card Slot

Available at Texas Instruments TI-99/4A computers.

Pinout

60 PIN UNKNOWN CONNECTOR on the computer

         59     Left     1
 Front ===================== Rear
         60     Right    2

Pin	Name	Dir	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*	→	System reset (active low)
7	GND	─	Ground
8	SCLK	nc	System clock (not connected)
9	LCP*	nc	CPU indicator 1=TI99 0=2nd generation (not connected)
10	AUDIO	←	Input audio (=AUDIOIN)
11	RDBENA*	←	Active low: enable flex cable data bus drivers (1K pull-up)
12	PCBEN	H	PCB enable for burn-in (always High)
13	HOLD*	H	Active low CPU hold request (always High)
14	IAQHA	nc	IAQ [or] HOLDA (logical or)
15	SENILA*	H	Interrupt level A sense enable (always High)
16	SENILB*	H	Interrupt level B sense enable (always High)
17	INTA*	←	Active low interrupt level A (=EXTINT*)
18	LOAD*	nc	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	→	Address bit 14
30	A15	→	Address bit 15 (LSB). Also CRU output bit.
31	A12	→	Address bit 12
32	A13	→	Address bit 13
33	A10	→	Address bit 10
34	A11	→	Address bit 11
35	A8	→	Address bit 8
36	A9	→	Address bit 9
37	A6	→	Address bit 6
38	A7	→	Address bit 7
39	A4	→	Address bit 4
40	A5	→	Address bit 5
41	A2	→	Address bit 2
42	A3	→	Address bit 3
43	A0	→	Address bit 0 (MSB)
44	A1	→	Address bit 1
45	AMB	H	Extra address bit. Always High.
46	AMA	H	Extra address bit. Always High.
47	GND	─	Ground
48	AMC	H	Extra address bit. Always High.
49	GND	─	Ground
50	CLKOUT*	→	Inversion of phase 3 clock (=PHI3*)
51	CRUCLK*	→	Inversion of TMS9900 CRUCLOCK pin
52	DBIN	→	Active high = read memory
53	GND	─	Ground
54	WE*	→	Write Enable (derived from TMS9900 WE* pin)
55	CRUIN	←	CRU input bit to TMS9900
56	MEMEN*	→	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.

Notes:

Signals buffered by 74LS244 in connection card: A0-A15, DBIN, MEMEN*, WE*, CLRCLK*, RESET*, CLKOUT.
Unbuffered signals: CRUIN, INTA*, AUDIOIN, READY
Data bus is buffered by two 74LS245 (one at each end of the cable),driven by RDBENA (direction set by DBIN).
All signals must be re-buffered on each card.
Always High lines (AMA, AMB, AMC, SENILA*, SENILB*, PCBEN, HOLD*) are pulled up to +5 Volts by 47 Ohms resistors.

Contributions

Joakim Ögren

Sources

TI-99/4A Card Slot pinout at Technick.net