* [[Amstrad Serial Interface]] ([[Amstrad]])
* [[Panda Electronics Communications Interface Unit]] (dual RS232 plus 8bit printer port) (Panda Electronics Ltd)
* [[Spectre Comms Serial Interface]] with Cage Comms software ([[Spectre Communications]])
* [[Vortex Disc Drives]] (disc drive/interface with optional RS232 port) ([[Vortex Computersysteme]])