At 07:42 PM 11/3/97 +0000, you wrote: >Can anyone tell me the requirements for programming the C54 in circuit, >what do you need to do with the MCLR pin. I can't find any data in the >microchip data book. I take it that the C54 can be programmed serially >as it can be programmed with the D. Tait type of programmer. nop, you need to use 16C554 if you want to use ICP. MCLR must have circuitry that allows to be pulled up to +12V, In programming same applies as for 16C84 Not sure if David's original software supports 16C55X programming our PIP02 does support, and supports amongst other programmers David Tait's programmer too antti -- Silicon Studio Ltd. -- http://www.sistudio.com