AMSSIO
From CPCWiki - THE Amstrad CPC encyclopedia!
The AMSSIO interface is a RS232 interface by the dane, Martin Zacho. As opposed to other serial interfaces the AMSSIO has to by installed on top of the Z80 CPU in the CPC!
AMSSIO exists in 3 different versions.
A new and improved version is the AMSSIO II.
Other RS232 interfaces for the CPC
Commercial:
Non commercial: