Hi Chris,
Currently, I am doing a project which using at89c2051 interface with 8255. But, it is very funny thing happend in my project. I can't interface with 8255 during high speed , but it can communicate in low speed. Hence , could you help to solve the problem ? If ok, could you pls send me your schematic and source code for me to refer . Your help is very appreiciated. Thank you very much.

Best Regards,
YY Cheong