ATasm is a 6502 command-line cross-assembler that is compatible with the original Mac/65 macro assembler released by OSS software. The aim of ATasm is to provide Atari home-brew coders with a comfortable and powerful toolset.
avrLab is an IDE (integrated development environment) for AVR microcontroller from ATMEL. It includes an editor with syntax highlighting. avrLab includes support for macro assembler (tavrasm and avra) as well as support for accessing the AVR via uisp.