The MSD SUPER DISK DRIVE is perhaps the most versatile and efficient disk drive built for the Commodore series of personal and business computers. The MSD SUPER DISK DRIVE is unique in that it features both serial and IEEE bus interfaces in one unit. The result of this flexibility is that the MSD SUPER DISK DRIVE is compatible with the Commodore SERIES 2001 {with BASIC Version 3.0 or higher), SERIES 3000 (with BASIC Version 3.0 or higher), SERIES 4000 (with BASIC Version 4.0), SERIES 8000 (with BASIC Version 4.0), COMMODORE 64 and VIC 20 computers. The wide range of compatibility is accomplished by providing a dual serial computer interface and an IEEE parallel interface. These two interfacing methods allow multiple disx drives /and printers to share the bus concurrently. The use of the parallel interface provides for significantly faster data transfer over the serial bus interface. With the addition of MSD's optional CIE or VIE interface board (IEEE interfaces for Commodore 64 or VIC 20) that plugs into the expansion port of the Commodore 64 or VIC 20 respectively, the user is even able to obtain this parallel speed enhancment on the Commodore 64 or VIC 20. The versatility is enhanced even more by the fact that the MSD SUPER DISK DRIVE is upward compatible with the commodore 2040 disk drive and read/write compatible with the Commodore 2031, 4040, 1540 and 1541 disk drives. This means that disks that were saved from the 2040 can be read by the MSD SUPER DISK DRIVE and disks that have been created on the 2331, 4040, 1540 and 1541 can be both read from and written to without any harm to existing programs on the disk.