Commodore Serial I/O

From HwB

Available on the Commodore VIC-20, C64, C128, C16, C116 and +4 computers.




6 PIN DIN (DIN45322) FEMALE at the Computer.


6 PIN DIN (DIN45322) MALE at the Cable.

Pin Name Dir Description
1 /SRQIN Arrowl.png Serial SRQIN
2 GND Arrow.png Ground
3 ATN Arrowlr.png Serial ATN In/Out
4 CLK Arrowlr.png Serial CLK In/Out
5 DATA Arrowlr.png Serial DATA In/Out
6 /RESET  ? Reset

Note: Direction is computer relative peripherals.


Serial service request in: Any device on the serial bus can bring this signal low when it requires attention from the VIC. The VIC will then take care of the device.


Serial attention in/out: The VIC uses this signal to start a command sequence for a device on the serial bus. When the VIC brings this signal low, all other devices on the bus start listening for the VIC to transmit an address. The device addressed must respond in a preset period of time; otherwise the VIC will assume that the device addressed is not on the bus, and will return an error in the status word.


Serial clock in/out: This signal is used for timing on the serial bus.


Serial data in/out: Data on the serial bus is transmitted one bit at a time on this line.


Not connected on some VIC-20 computers.