Hi, I have a strange problem. I am converting an automatic build script in Perl from using direct calls to the Windows OS to invoking a51 with an '@commandfile' format because the invocation line has exceeded 500 characters. What is really weird is that with code that assembles and links with no errors with direct invocation, I am getting a fatal error "CANNOT CREATE FILE" (768) when the assembler tries to generate the object file with the commandfile method. Again, there are no errors with direct invocation. My assembler: A51 MACRO ASSEMBLER V6.02 - SN: K1F4U-60444U COPYRIGHT KEIL ELEKTRONIK GmbH 1987 - 2000 I am running cmd.exe under Windows XP service pack 1. Thanks, Bob C.