AY-3-8910 programmable sound generator (40-pin) pinout

DIP-40. Three tone voices, noise and envelope, plus two 8-bit I/O ports (the MSX joystick ports and the cassette input)

On the MSX it sits at I/O $A0 (address latch), $A1 (data write) and $A2 (data read), clocked at 1.7897725 MHz (half the CPU clock). Port A is input: bits 0-5 read the selected joystick port (directions and triggers), bit 6 the keyboard layout jumper (Japanese machines), bit 7 the cassette input. Port B is output: trigger and pin 8 outputs, bit 6 selects joystick port 1 or 2, bit 7 the Kana LED. So a dead PSG means no sound, no joysticks and no tape loading. The YM2149 is a drop-in: pin 26 is SEL there (pull-up; open = same as the AY), and its DAC is louder. The 28-pin AY-3-8912 (timex.js) is the same chip without port B.

Open the interactive AY-3-8910 pinout

Pins

Pin	Name	Type	Signal
1	VSS	ground	Ground.
2	NC	nc	Not connected.
3	ANALOG B	audio	Channel B D/A output, up to 1 V p-p.
4	ANALOG A	audio	Channel A D/A output, up to 1 V p-p.
5	NC	nc	Not connected.
6	IOB7	io	Port B bit 7. MSX: Kana LED (Japanese machines; LOW = on).
7	IOB6	io	Port B bit 6. MSX: selects joystick port 1 (LOW) or port 2 (HIGH) onto port A.
8	IOB5	io	Port B bit 5. MSX: joystick port 2 pin 8 output.
9	IOB4	io	Port B bit 4. MSX: joystick port 1 pin 8 output.
10	IOB3	io	Port B bit 3. MSX: port 2 pin 7 through an open-collector buffer (keep HIGH to read the trigger).
11	IOB2	io	Port B bit 2. MSX: port 2 pin 6 through an open-collector buffer.
12	IOB1	io	Port B bit 1. MSX: port 1 pin 7 through an open-collector buffer.
13	IOB0	io	Port B bit 0. MSX: port 1 pin 6 through an open-collector buffer.
14	IOA7	io	Port A bit 7. MSX: cassette read (CSAR) input.
15	IOA6	io	Port A bit 6. MSX: keyboard layout select (JIS HIGH, syllable LOW; Japanese machines).
16	IOA5	io	Port A bit 5. MSX: trigger B (pin 7) of the selected joystick port.
17	IOA4	io	Port A bit 4. MSX: trigger A (pin 6) of the selected joystick port.
18	IOA3	io	Port A bit 3. MSX: RIGHT of the selected port.
19	IOA2	io	Port A bit 2. MSX: LEFT.
20	IOA1	io	Port A bit 1. MSX: BACK (down).
21	IOA0	io	Port A bit 0. MSX: FWD (up).
22	CLOCK	clock	Timing reference for tone, noise and envelope (TTL).
23	/RESET	ctrl	LOW clears every register. On-chip pull-up.
24	/A9	addr	Extra chip-select address bit (active LOW), on-chip pull-down; usually left open or grounded.
25	A8	addr	Extra chip-select address bit, on-chip pull-up; usually tied HIGH.
26	TEST 2	nc	GI test pin; leave open. On a YM2149 this is SEL (pull-up): LOW divides the input clock by 2. UNVERIFIED
27	BDIR	ctrl	Bus direction. With BC1 (BC2 HIGH): 0 0 inactive, 0 1 read, 1 0 write, 1 1 latch address.
28	BC2	ctrl	Bus control 2; may be tied HIGH so only BDIR and BC1 are driven.
29	BC1	ctrl	Bus control 1.
30	DA7	data	Data/address bit 7.
31	DA6	data	Data/address bit 6.
32	DA5	data	Data/address bit 5.
33	DA4	data	Data/address bit 4.
34	DA3	data	Data/address bit 3.
35	DA2	data	Data/address bit 2.
36	DA1	data	Data/address bit 1.
37	DA0	data	Data/address bit 0.
38	ANALOG C	audio	Channel C D/A output, up to 1 V p-p.
39	TEST 1	nc	GI test pin. Leave open.
40	VCC	power	+5 V supply.

Fitted in

MSX1 (generic) Varies by maker; AY-3-8910 or Yamaha YM2149, or inside an MSX-Engine on late boards
MSX2 (generic) Discrete AY-3-8910 / YM2149 on early MSX2; inside the S3527 or S1985 MSX-Engine on most

AY-3-8910 programmable sound generator (40-pin) pinout

Pins

Fitted in

Sources