One of the most commonly used ports at all. Many extensions like parallel floppy speeders, eprommers, relay cards, etc. connect to the user port. Please note that the SX-64's user port seems to be slightly INCOMPATIBLE which means that certain user port devices can cause DAMAGE! See description of pin 10-11.
ASCII version: 1 2 3 4 5 6 7 8 9 10 11 12 +--===+===-===-===-===-===-===-===-===-===+===-===--+ | | | | +--===+===-===-===-===-===-===-===-===-===+===-===--+ A B C D E F H J K L M N
|2||+5V DC||-||Supply voltage. Max. 100mA.|
|3||/RESET||in/out||RESET. When pulling this line to LOW, the CPU resets and waits for a LOW-HIGH transistion to load the PC with the value stored in $fffc/$fffd. After power-up, timer A in the NE556 pulls this line to LOW for a short time and half a second later back to HIGH.|
|4||CNT1||progr.||Count1. Connected to CNT of CIA #1.|
|5||SP1||progr.||Serial port 1. Serial I/O of shift register (SP) of CIA #1.|
|6||CNT2||progr.||Count2. Connected to CNT of CIA #2.|
|7||SP2||progr.||Serial port 2. Serial I/O of shift register (SP) of CIA #2.|
|8||/PC2||out||Port control 2. Connected to /PC of CIA #2. Becomes LOW for one cycle after read or write access of port register B. Open collector output, therefore needs pull-up resistor.|
|9||SER ATN||out||Serial attention. Attention line of serial bus. Can be used as output (inverted PA3 of CIA #2) and via open-collector ouput as input, too (have to verify that).|
|10-11||9 VAC||-||Supply voltage. Max. 100mA. WARNING! It is said that one of the pins is GROUNDED in the SX-64! This means for example that you cannot use your Commodore Vicmodem, because it will damage your SX-64! |
|B||/FLAG2||in||A negative edge at this pin sets the FLAG bit in the interrupt control register of CIA #2.|
|C-L||PB0-PB7||progr.||Port register B of CIA #2. Each line is individually programmable as in- or output.|
|M||PA2||progr.||Port register A, bit 2 of CIA #2.|
Note: All pictures show the plug side.