0UziMonkeyBest Answer 10 years ago ReplyUpvotePIC chips with c in the name (PIC16C, PIC18C, etc) are one-time program chips. If it's already programmed, you can't put a new program on it. Use the flash-based PICxxF chips instead. They can be programmed with a programmer, usually connected to your serial or USB port. There are also a number of DIY programmers you can build for cheap, and some development boards that have built in programmers for cheap as well.