MAC/65 is a 6502 assembler written by Stephen D. Lawrow for the Atari 8-bit family of home computers. MAC/65 was first released on disk by Optimized Systems Software in 1982, with the program requiring 16 KB RAM. A bank switched "SuperCartridge" from OSS followed in January 1984 for US$99, occupying only 8 KB. According to Lawrow, MAC/65 was used to compile not only itself, but BASIC XL and BASIC XE.