The Sinclair QL Forum

Hi,

Can anyone please help with the QL serial printer pinnout and interface?
I have a serial printer for Commodore, how could the signals be easily easily converted to map those needed by the QL SER port?

Commodore printer serial has got these signals,

SRQ Not used.

GND Signal ground.

ATN Serial Attention In
High ..................... Signifies the data transfer mode.
Low ..................... Signifies the command transfer mode.

CLK Serial Clock In
The printer begins reading data on the rising edge of this signal.

DATA Serial Data In/Out
IN: Conveys commands and data from the computer to the printer,
OUT: High indicates printer ready Low indicates printer busy.

RESET
When this signal level goes low, the printer is initialized and the memory buffer is cleared.

Many thanks
Tomas

The Commodore serial port system used by Commodore printers is a synchronous serial port (presumably using +5V levels).
The serial port on the QL is a cut down RS232 asynchronous serial port using +12V and -12V levels.
Without having some extra hardware (like a micro controller and level shifters) you cannot connect the two systems.

Mark