The first assembler for the Atari available to the public was Atari Assembler Editor, originally written by Shepardson Microsystems and sold by Atari 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 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.