C64 RS232 User Port
From HwB
Available on the Commodore C64 & C128. Software emulated. The signals does not have true RS232 levels. It's TTL level, and RXD/TXD is inverted. It's just the normal User Port, used as a RS232 port.
Pinout
24 PIN MALE EDGE (DZM 12 DREH) at the computer.
| Pin | Name | RS232 | Description |
|---|---|---|---|
| A | GND | GND | Protective Ground |
| B+C | FLAG2+PB0 | RxD | Receive Data (Must be applied to both pins!) |
| D | PB1 | RTS | Ready To Send |
| E | PB2 | DTR | Data Terminal Ready |
| F | PB3 | RI | Ring Indicator |
| H | PB4 | DCD | Data Carrier Detect |
| K | PB6 | CTS | Clear To Send |
| L | PB7 | DSR | Data Set Ready |
| M | PA2 | TxD | Transmit Data |
| N | GND | GND | Signal Ground |
Contributions
Sources
- Usenet posting in comp.sys.cbm - Help on modem -> c64 by Lasher Glenn
- Commodore 64 Programmer's Reference Guide