An assembler which runs on one type of processor and produces machine code for another.
There is a set of 6502, 68xx and Zilog Z80 and 8085 cross-assemblers in C by <firstname.lastname@example.org> and Alan R. Baldwin. They run under MS-DOS and could be compiled to run under Unix and on the Amiga and Atari ST.
See also fas.
Try this search on Wikipedia, OneLook, Google
Nearby terms: CRM « crock « cron « cross-assembler » cross-compiler » cross-platform » cross-post