I have one more question related to 8255. I hope that the experts here can solve my problem. I set port c (lower) as output port and port c (upper) as input port. I needed to read and write port c at the same time. Will my system be crashed due to I write some values to port c and read the new values at the same time?

e.g. If I write the value FFh to port c, then will the system read all the '1's in port c (upper) without actually read the values from the output devices attached in port c (upper)?