Commodore 64 / 128 User I/O pinout

bus or interface

24 pin DZM 12 DREH connector
at the computer

Top side
1	GND	Ground
2	+5VDC	(100 mA max)
3	/RESET	Reset, will force a Cold Start. Also a reset output for devices.
4	CNT1	Serial port counter from CIA #1
5	SP1	Serial port from CIA #1
6	CNT2	Serial port counter from CIA #2
7	SP2	Serial port from CIA #2
8	/PC2	Handshaking line from CIA #2
9	ATN	This pin is connected to the ATN line of the serial bus
10	+9VAC	(+ phase) Connected directly to the Commodore 64 transformer (100 mA max)
11	+9VAC	(- phase) Connected directly to the Commodore 64 transformer (100 mA max)
12	GND	Ground
Bottom side
A	GND	Ground
B	/FLAG2	The Commodore 64 gives you complete control over Port B on VIA chip #1. Eight lines for input or output are available, as well as 2 lines for handshaking with an outside device. The I/O lines for Port B are controlled by two locations. One is the port itself, and is located at 56577 ($DD01 hex). Naturally you PEEK it to read an input, or POKE it to set an output. Each of the eight I/O lines can be set up as either an input or an output by setting the data direction register properly. It is located at 56579 ($DD03 hex).
C	PB0
D	PB1
E	PB2
F	PB3
H	PB4
J	PB5
K	PB6
L	PB7
M	PA2
N	GND	Ground

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Pinouts.ru > Buses and slots connectors pinouts > Pinout of Commodore 64 / 128 User I/O and layout of 24 pin DZM 12 DREH connector	Document status:	unknown
Source(s) of this and additional information: Commodore 64 User Manual, Commodore 64 Programmer"s Reference Guide	0 reports
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