CPCI RS232 Interface
As the standard CPC series does not include a RS232, this interface was very handy in order to communicate with other computers(eg. IBM PCs). A major drawback was the missing interrupt line which means that your programs have to poll the interface.
Contains a single 25pin DSUB connector, a MC6850 chip (ACIA), MAX 232 voltage converter, 74LS138 and 74LS85 address decoders, and a 4MHz oscillator with HEF 4060 clock divider, the clock divider connects to a mechanic switch, allowing to select between 19.2kHz and 38.4kHz. Four dip-switches allow to select the port addresses (FxDCh and FxDDh, with x=0..F, usually x=8).
F8DCh CPCI Serial Interface MC6850 Control/Status Register (R/W) F8DDh CPCI Serial Interface MC6850 Data Register (R/W)