Shepardson Microsystems used a cross-compiler to write BASIC, and at the same time they began development of their own assembler which was later released as the Atari Assembler Editor in ROM cartridge format. Assembler/Editor lacked many features, and was only suitable for small programs, so Atari also released the disk-based high-end Atari Macro Assembler. Macro Assembler was glacially slow, as it was entirely disk based. This led to a thriving market for 3rd party assemblers and debuggers to fix the problems seen in one or the other.