About parallel and serial communications

The Spectrum 128, +2, +2A and +3 feature a built-in RS-232/MIDI port. This was commonly used to connect a serial printer. The 128's LLIST and LPRINT commands were modified to print using this port rather than continuing to use the ZX Printer.

In addition to the RS-232/MIDI port on earlier models, a Centronics (parallel) port was added to +2A/+3 Spectrums. This allows any modern parallel port printer to be connected to the Spectrum. By default, +3 BASIC will send the output of LLIST and LPRINT to this port rather than the RS-232 port. This can be changed though using the FORMAT LPRINT "R" command.

Spectaculator can capture output sent to the RS-232 port or the Centronics port and redirect it to a file, the Windows clipboard, a COM port or an LPT port. This allows you to LPRINT and LLIST directly to a printer connected to your computer.

For further details on using the Centronics and RS-232 ports, see the Spectrum +3 manual - available here.