IC number:	6526 / 8521 ¹
IC function:	CIA (Complex Interface Adapter)
Related components:	8520 (successor)

¹ Many times a 8521 is actually marked 6526. When this is the case, the code 216A will also be printed on the component.

Component documentation

IC number	Manufacturer	Documentation
6526, 8521	MOS Technology / CSG	Not available

Component versions

IC number	Package	Speed	CBM part number	CBM part description
MCS6526	40-Pin Ceramic DIP	1 MHz	906108-01	6526
MPS6526	40-Pin Plastic DIP	1 MHz
MCS6526A	40-Pin Ceramic DIP	2 MHz	906108-02	6526A
MPS6526A	40-Pin Plastic DIP	2 MHz

Positions

Device	Positions	Package	Speed
C64	U1, U2	DIP	1 MHz
C64C	U1, U2	DIP	1 MHz
SX 64 I/O board	UB2, UB3	DIP	2 MHz
C128	U1, U4	DIP	1 MHz
C128D CR	U1, U4	DIP	1 MHz
CBM II lo-profile	U1	DIP	2 MHz
CBM II hi-profile	U11	DIP	2 MHz
1571	U20	DIP	2 MHz

• The 1571 diskdrive can use either the 6526A or 8520 CIA.

Pinout

Pin	Type	Name	Signal name
			C64 U1, C64C U1, SX 64 I/O board UB3, C128 U1, C128D CR U1	C64 U2, C64C U2, SX 64 I/O board UB2, C128 U4, C128D CR U4	CBM II lo-profile, CBM II hi-profile	1571
1	Power	VSS	GND		GND	GND
2	I/O	PA0	COL0 (JOYB0)	VAI4_	connected to P1 and U3	unused
3	I/O	PA1	COL1 (JOYB1)	VAI5_	connected to P1 and U3	unused
4	I/O	PA2	COL2 (JOYB2)	PA2	connected to P1 and U3	unused
5	I/O	PA3	COL3 (JOYB3)	ATN_OUT	connected to P1 and U3	unused
6	I/O	PA4	COL4	CLK_OUT	connected to P1 and U3	unused
7	I/O	PA5	COL5	DATA_OUT	connected to P1 and U3	unused
8	I/O	PA6	COL6	CLK	connected to P1 and U3	unused
9	I/O	PA7	COL7	DATA	connected to P1 and U3	unused
10	I/O	PB0	ROW0 (JOYA0)	PB0	connected to P1	unused
11	I/O	PB1	ROW1 (JOYA1)	PB1	connected to P1	unused
12	I/O	PB2	ROW2 (JOYA2)	PB2	connected to P1	unused
13	I/O	PB3	ROW3 (JOYA3)	PB3	connected to P1	unused
14	I/O	PB4	ROW4 (BTNA/LP)	PB4	connected to P1	unused
15	I/O	PB5	ROW5	PB5	connected to P1	unused
16	I/O	PB6	ROW6	PB6	connected to P1	unused
17	I/O	PB7	ROW7	PB7	connected to P1	unused
18	Output	PC	unused	PC2_	connected to P1	unused
19	Input	TOD	60Hz		TODCLK	unused
20	Power	VCC	+5		+5V	+5
21	Output	IRQ_	IRQ_	NMI_	CIAIRQ_	_IRQ
22	Input	R/W	R/W_		SR/W_	R/_W
23	Input	CS_	CIA1_	CIA2_	CIACS_	connected to U5
24	Input	FLAG_	CASS_RD (SRQ_IN_)	FLAG2_	CASREAD	unused
25	Input	Ø2	Ø2		SØ2	PHI_2
26..33	I/O	DB7..DB0	D7..D0		BD7..BD0	D7..D0
34	Input	RES_	RESET_		RES_	_RES
35..38	Input	RS3..RS0	A3..A0		BA3..BA0	A3...A0
39	I/O	SP	SP1	SP2	connected to P1	connected to U19
40	I/O	CNT	CNT1	CNT2	connected to P1	connected to U19

• On the C128 and C128D CR the signal Ø2 is called 1MHz