ulm@gentoo.org zmac is a Z80 macro cross-assembler. It has all the features you'd expect. It assembles the specified input file and produces raw binary output. (It can optionally produce CP/M-style Intel hex format.) By default it also produces a nicely-formatted listing of the m/c alongside the source. As well as normal Z80 programs, zmac lets you write 8080 programs in Z80 assembly.