David Griffith <dave at 661.org> wrote: A couple of observations on the following code: 1/ It is written for, and uses TOPS20 syscalls. If you intend to run this under TOPS10 change the syscalls (LITES% and DISMS%) to the equvialent TOPS10 counterparts, can be done by including these lines: SEARCH UUOSYM OPDEF LITES% [LIGHTS] OPDEF DISMS% [HIBER] 2/ The program uses the CIRC instruction, which is not present in stock DEC processors, and possibly not known to MACRO-10. You could try OPDEF CIRC [247000,,0] if that is indeed the problem. [source code trimmed down] --Johnny