* [[RS232|Serial Interface]] (?) (1986)
* [[Service Manuals|SERVICE MANUALS]] ([[Amstrad|AMSTRAD]]) FIX 464,6128,464+,6128+, GX4000,DDI-1,FD-1,CT-1,MP-3
* [[ABBA switch|SIDE SWITCH]], External (?) USE BOTH SIDES OF 3.5 " DISCS IN AMSDOS"
* [[ABBA switch|Side Switch]], Internal ([[STS]]/[[Hangman|Rob Scott]])
* Sideways ROM ([[KDS Electronics]])