.. Just as an update - the Z80 card is coming along well - just a few timing problems to go. Although it boots CPM and behaves correctly, a real softcard diagnostics app would help a lot. If anyone has any CPM or softcard diagnostics, it would be much appreciated to grab a cop to confirm CB's doing the right thing. http://www.applelogic.org:88/AL/carteblancheZ80.JPG steve