The MSD Super Disk was a series of floppy disk

Floppy disk

A floppy disk is a disk storage medium composed of a disk of thin and flexible magnetic storage medium, sealed in a rectangular plastic carrier lined with fabric that removes dust particles...

 drives produced by Micro Systems Development for use with Commodore

Commodore International

Commodore is the commonly used name for Commodore Business Machines , the U.S.-based home computer manufacturer and electronics manufacturer headquartered in West Chester, Pennsylvania, which also housed Commodore's corporate parent company, Commodore International Limited...

 8-bit

8-bit

The first widely adopted 8-bit microprocessor was the Intel 8080, being used in many hobbyist computers of the late 1970s and early 1980s, often running the CP/M operating system. The Zilog Z80 and the Motorola 6800 were also used in similar computers...

 home computer

Home computer

Home computers were a class of microcomputers entering the market in 1977, and becoming increasingly common during the 1980s. They were marketed to consumers as affordable and accessible computers that, for the first time, were intended for the use of a single nontechnical user...

s. Two different versions of the MSD Super Disk were available: the single-drive SD-1 and the dual-drive SD-2.

Introduction

The MSD Super Disk drives were the first third-party devices designed for compatibility with the Commodore 64

Commodore 64

The Commodore 64 is an 8-bit home computer introduced by Commodore International in January 1982.Volume production started in the spring of 1982, with machines being released on to the market in August at a price of US$595...

, although other manufacturers soon followed suit. The MSD drives included both an IEEE-488

IEEE-488

IEEE-488 is a short-range digital communications bus specification. It was created for use with automated test equipment in the late 1960s, and is still in use for that purpose. IEEE-488 was created as HP-IB , and is commonly called GPIB...

 parallel interface

Parallel port

A parallel port is a type of interface found on computers for connecting various peripherals. In computing, a parallel port is a parallel communication physical interface. It is also known as a printer port or Centronics port...

 and the custom Commodore serial interface

Serial port

In computing, a serial port is a serial communication physical interface through which information transfers in or out one bit at a time...

. Therefore, they could be connected to any Commodore 8-bit system, from the Commodore PET

Commodore PET

The Commodore PET was a home/personal computer produced from 1977 by Commodore International...

 to the C64

Commodore 64

The Commodore 64 is an 8-bit home computer introduced by Commodore International in January 1982.Volume production started in the spring of 1982, with machines being released on to the market in August at a price of US$595...

 and C128

Commodore 128

The Commodore 128 home/personal computer was the last 8-bit machine commercially released by Commodore Business Machines...

, without any converters or add-on devices.

Features and pricing

The MSD drives were more expensive than their Commodore counterparts. 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 dual SD-2 was listed at $449.95.) However, they did offer several advantages to justify the higher price. 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). While program loading and saving was no faster than on a 1541 drive (since the same firmware and serial interface was used), a disk could be formatted in only 18 seconds on the MSD Super Disk series, compared to 1 minute and 22 seconds on the 1541 (p. 26). Also, the MSD SD-2 incorporated the Commodore DOS

Commodore DOS

Commodore DOS, aka CBM DOS, was the disk operating system used with Commodore's 8-bit computers. Unlike most other DOS systems before or since—which are booted from disk into the main computer's own RAM at startup, and executed there—CBM DOS was executed internally in the drive: the DOS...

 Duplicate command from the old Commodore PET dual drive

Commodore 4040

The Commodore 4040 and its sibling, the 2040 and the European marketed 3040, were dual unit 5¼" floppy disk drives for Commodore International computers...

series, which allowed it to copy an entire disk in less than 2 minutes. The DOS Copy command could also be used to copy files from one drive to another on the MSD SD-2, a feature not available with two 1541 single drives. However, the MSD Super Disk drives had difficulty loading most copy-protected software, due to substantial differences in the DOS code and memory mapping.