MSD Super Disk

The MSD Super Disk is a series of 5¼-inch floppy disk drives compatible to some degree with the Commodore 1541 and produced by Micro Systems Development (Dallas, Texas; later MSD Systems) for use with Commodore 8-bit home computers. Two different versions of the MSD Super Disk were available: the single-drive model, SD-1; and the dual-drive model, SD-2.

Introduced in 1983, the MSD Super Disk drives are the first third-party devices designed for compatibility with the Commodore 64, although other manufacturers soon followed suit. The MSD drives include both an IEEE-488 parallel interface and the custom Commodore serial interface. Therefore, they can be connected to any Commodore 8-bit system, from the Commodore PET to the C64 and C128, without any converters or other add-on devices.

The MSD SD-1 was more expensive than the Commodore 1541. For instance, a typical mail-order advertisement in the January 1985 issue of RUN Magazine (p. 91) lists the MSD SD-1 single drive at $249.95, compared to $199.95 for the Commodore 1541. The SD-2 was listed at $449.95, much less than the comparable Commodore PET dual drive CBM 4040 which sold for $699 (Byte magazine, August 1983, p. 311).

However, they do offer several advantages to justify the higher price over the 1541. In an August 1985 review of 1541 replacements, RUN Magazine wrote that the MSD SD-2 was "built like a tank and can run 24 hours a day for weeks" (p. 28).

Due to the serial interface's limitations, program loading and saving is no faster than on a 1541 drive when that interface is used. However, the SD-1 and SD-2 are several times as fast when connected via the IEEE-488 interface. MSD Systems also offered the VIE and CIE IEEE-488 interface for the VIC-20 and Commodore 64, respectively. A blank disk can be formatted in only 18 seconds on the MSD Super Disk series, compared to 1 minute and 22 seconds on the 1541 (p. 26).

...
Wikipedia