It is perfectly good MPASM syntax. Why don't you use MPASM? MPASM is a DOS app too. Also FREE, including the docs. GL, Walt... -----Original Message----- From: Kevin Thomas [mailto:vk5kks@SENET.COM.AU] Sent: Thursday, February 24, 2000 11:09 AM To: PICLIST@MITVMA.MIT.EDU Subject: Assembler Error The following line produces the error 'bad byte value' movlw B'00000001' The assembler points to the beginning of the binary number. I'm using AF84 version 1.02 - a DOS assembler. Any good source of knowledge for a raw beginer in assembly language would be nice. I cannot find anything that caters for idiots. Kevin