Are you reprogramming it in-circuit, or pulling it out and using a stand-alone programmer? alan smith wrote: > Subject: [PIC] 12F509 >=20 > Flash part...so should be able to reprogram it. >=20 > Using an ICD, program it...drop it in circuit, works fine. >=20 > Try to reprogram it....has errors always at address 0x04.data didnt > match..so it crashes.=A0 Any ideas? --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .