The TED offered 121-color (15 colors × 8 luminance levels + black) video, a palette matched only by Atari's 8-bit computer line and the Enterprise at the time, and 320×200 video resolution, similar to many computers intended to be capable of connecting to a television. The Plus/4's memory map, which used bank switching far more extensively than the C64, gave it a 56% larger amount of user-accessible memory than the C64 for programming in BASIC, and its BASIC programming language was vastly improved, adding sound and graphics commands as well as looping commands that improved program structure. Commodore released a high-speed floppy disk drive for the Plus/4, the Commodore 1551, which offered much better performance than the C64/1541 combination because it used a parallel interface rather than a serial bus. The 1551 plugged into the cartridge port.