Hi,

Yes I had a similar problem in reading from a DTMF chip.

after writing I didn't set the port to 0xff before reading the data in, result the low ports always read low even if it was a high bit from DTMF chip on those ports.

Intel port structure needs a port bit to be set to high before reading any external input.

I think in Motorola's port structure you don't need doing this ??

Simon