# TI-99/4A Card Slot

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.

Contributor: | Joakim Ögren

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

Copyright © The Hardware Book Team 1996-2004.
May be copied and redistributed, partially or in whole, as appropriate.
Document last modified: 2002-01-10