Hi, some time ago there was some discussion on the list with regard to AN555 and a Pic 16C84. Someone tried to get the code running on an 84. I've unfortunately trashed the digest in which the answer to that question appeared. Could anyone shed some light on this again. What I want is an interupt driven serial receiver. The project in which it will be used is a serial to centronics converter. This seems rather straightforward, and in fact it is if there enough time between bytes. In my case (Mac to Centronics printer) the computer does not react instantaniously on CTS drops, so I need a ringbuffer to catch bytes until the computer stops spitting them out. As far as I can see these two loops (receiving and managing the ringbuffer) can only be accomplished by having one of them run by interrupts. The input is most obvious. I've tried to get the AN555 to run today, with no luck sofar. Yours, Ronald