@Matt_H
IIRC the CV643D has a jumper that forces to ZII mode but . . . this isn't the right way IMHO.
@dandelion
try to find the jumper settings, on your CV3D user manual.
Ciao
NOTE- "the CV643D works only with a mobo clock of 25 Mhz, so with some accellerator cards, couldn't works".
"SuperBuster 11 suggested"
By the way: you haven't yet answer if the card has the SD or not (very important for the configuration)
.