MM5740 Keyboard Encoder pinout

DIP-40. Keyboard encoder (early II and II+)

PMOS encoder on the II and II+ keyboard: it scans the X1-X9 / Y1-Y10 matrix and puts a 9-bit code on B1-B9 with a data strobe. Supplies: VSS +5 V (pin 32), VLL 0 V (pin 2), VGG -12 V (pin 18). Its outputs are buffered by a 7404 on the keyboard and reach the main board on the 16-pin keyboard connector. The IIe moved to the AY-5-3600.

Open the interactive MM5740 pinout

Pins

Pin	Name	Type	Signal
1	B3	data	Key code bit 3.
2	VLL	ground	VLL, 0 V (ground).
3	CLOCK	clock	Scan clock from the board.
4	X9	kbd	Matrix row X9.
5	X8	kbd	Matrix row X8.
6	X7	kbd	Matrix row X7.
7	X6	kbd	Matrix row X6.
8	X5	kbd	Matrix row X5.
9	X4	kbd	Matrix row X4.
10	X3	kbd	Matrix row X3.
11	X2	kbd	Matrix row X2.
12	X1	kbd	Matrix row X1.
13	DStrbO	ctrl	Data strobe output: pulses when a key code is ready.
14	DStrbC	ctrl	Data strobe control input: sets the strobe pulse width.
15	OutEn	ctrl	Output enable for the B1-B9 code lines (TRI-STATE).
16	Repeat	ctrl	Repeat key input.
17	KeyBnce	ctrl	Key-bounce mask: external capacitor sets the debounce time.
18	VGG	power	VGG, -12 V gate supply.
19	Control	kbd	Control key input.
20	ShiftLk	kbd	Shift Lock I/O: input from the lock key; can also drive an indicator.
21	SHIFT	kbd	Shift key input.
22	Y10	kbd	Matrix column Y10.
23	Y1	kbd	Matrix column Y1.
24	Y2	kbd	Matrix column Y2.
25	Y3	kbd	Matrix column Y3.
26	Y4	kbd	Matrix column Y4.
27	Y5	kbd	Matrix column Y5.
28	Y6	kbd	Matrix column Y6.
29	Y7	kbd	Matrix column Y7.
30	Y8	kbd	Matrix column Y8.
31	Y9	kbd	Matrix column Y9.
32	VSS	power	VSS, +5 V supply (PMOS substrate).
33	B5	data	Key code bit 5.
34	B6	data	Key code bit 6.
35	B7	data	Key code bit 7.
36	B8	data	Key code bit 8.
37	B1	data	Key code bit 1.
38	B2	data	Key code bit 2.
39	B9	data	Key code bit 9.
40	B4	data	Key code bit 4.

Fitted in

Apple II Keyboard PCB
Apple II Plus Keyboard PCB

MM5740 Keyboard Encoder pinout

Pins

Fitted in

Sources