Simple Z80 IN out question

Hi Folks,

I've been working on my Retrochallenge project, adding a CF card reader to my Interak-1 Z80 machine (www.randomorbit.co.uk) and I've run into a Z80 problem that has me stumped.

After lots of trial and error it boils down to this...

I'm trying to read from port 0x67, the CF card status register.

If I use IN A, (0x67) I get 0x40

If I load BC with 0x67 and use IN A, (C) I get 0x78.

I can't see why there is a difference.

Please can someone explain?


Thanks,


Andy.