>> If so, those electronics would have to allow the bi-directionality of >> the lines > They do. They don't connect simply across the pins either. What I was imagining would be the case is the PIC and the PC sharing the lines, similar to the way I2C or serial devices do, with paralleled open-collectors Joe * * ********** Quality PIC programmers http://www.embedinc.com/products/index.htm --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .