Hi All;
i built a circuit that converts some rs 232 data to the at keyboard data format. The circuit is placed between the standart keyboard and the IBM pc and the voltage needed is supplied form the keyboard line directly. The circuit have a 89c2051 and a max 232 chip. The incomming serial data is converted to the proper scan codes and then transmitted to the ps/2 input of the pc. The problem is that nearly every time the uC transmits a byte to the pc, the pc BEEPs and some time it writes the character that uC sent but sometime it does not. But when i disconnect the original keyboard, then it seems to be ok, every character that is sent from the uC is written properly by the PC. I think when uC sends data to the pc, the original keyboard thinks that the PC is trying to communicate with itself, but in a wrong way!!(since sending data from pc to keyboard and from keyboard to pc is different). But i'm not sure and don't know how to deal with the problem? What should i do or how should i solve the problem?

Regards.
Ertan Balaban.