Codemasters CD
From CPCWiki - THE Amstrad CPC encyclopedia!
The Codemasters CD was a compilation of games from Codemasters which came on a CD.
The games were stored as audio, but in a special fastloader form.
In order to use the CD you connected the CPC to a CD player using a special cable which connected to the joystick port. Special loader software was provided on cassette.
Such an exotic feature was choosen because every Amstrad did include a Joystick port.
Yet the 6128Plus lacks of Tape port.