I am not sure if this is not if this is the right place to post this
question.I am interfacing pic microcontroller (pic18f452) to
FDC37c672 from SMSC. FDC37c672 has some UART and IrDA
capabilities which I want to explot.

It has an ISA bus interface. I am able to read the
registers from the FDC37C672.
But for some reason I am unable to write to the
FDC37C672 using PIC using C. So, I connected it to
Computer's ISA slot and wrote code Visual C++. On PC,
I am able to read and write to FDC37C672. I am not
sure what is wrong with my circuit. Did anyone ever
face any problem like this. I want to learn from your
experience.
Please feel free to suggest me. I can send you
schematics of my PCB board if you are interested in.

Thanks,
Kalyan