Merlin was a macroassembler developed by mathematics professor Glen Bredon, initially running on the Apple II family under DOS 3.3, for the 6502 processor. The product was published commercially by Southwestern Data Systems, later known as Roger Wagner Publishing. Merlin continued to be updated as successors to the 6502 became available. Merlin included an integrated source code editor (initially a line editor; later versions included a full-screen editor) and also a disassembler, called Sourceror. Merlin was a popular assembler on the Apple II platform, and source files in Merlin format are common in Apple II archives today. Versions for the Commodore 64 and Commodore 128, dubbed Merlin 64 and Merlin 128 respectively, were also released.