page_title: Commodore 64 peripherals
section_title: Floppy disk drives
hierarchical_section_title: Commodore 64 peripherals / Storage / Floppy disk drives
caption_attribution_description: Deutsch: Commodore 1541C 5,25-Zoll-Diskettenlaufwerk (weiße Version mit Hebelverschluß). Oben drauf das serielle Anschlusskabel. English: Commodore 1541C 5.25" Diskette Drive (white version with lever locking mechanism). Serial cable on top.
context_page_description: Due to the backwards compatibility of the Commodore 128, most peripherals will work on that system, as well. There's some compatibility with the VIC-20 and PET too.
context_section_description: Although usually not supplied with the machine, floppy disk drives of the 5¼ inch (1541, 1570 and 1571) and, later, 3½ inch (1581) variety were available from Commodore.
  The 1541 was the standard floppy disk drive for the Commodore 64, with nearly all disk-based software programs released for the computer being distributed in the 1541 compatible floppy disk format. The 1541 was very slow in loading programs because of a poorly implemented serial bus, a legacy of the Commodore VIC-20.
  The 1541 disk drive was notorious for not only its slow performance and large physical size compared to the C64 (the drive is almost as deep as the computer is wide), but also for the drive mechanisms installed during early production runs, which quickly gained a bad reputation for their mechanical unreliability.
  Perhaps the most common failure involved the drive's read-write head mechanism losing its alignment. Due to lack of hardware support for detecting track zero position, Commodore DOS formatting routines and many complex software copy-protection schemes (which used data stored on nonstandard tracks on floppies) had to rely on moving the head specified number of steps in order to make sure that the desired head position for formatting or reading the data was reached. Since after physically reaching track zero, further movement attempts caused the head drive mechanism to slam (producing the infamous, loud, telltale knocking sound) into a mechanical stop, the repetitive strain often drove the head mechanism out of precise alignment, resulting in read errors and necessitating repairs. As a side note: some demos exploited the sound generated by the head moving stepper motor to force the disk drive to play crude tunes ("Bicycle Built For Two" was one) by varying the frequency of step requests sent to the motor.
  Also, as with the C64, 1541 drives tended to overheat due to a design that did not permit adequate cooling (potentially fixed by mounting a small fan to the case). Many of the 1541's design problems were eventually rectified in Commodore's 1541-II disk drive, which was compatible with the older units. The power supply unit was not housed inside the drive case; hence, the 1541-II size was significantly smaller and did not overheat.
  Because of the drive's initial high cost (about as much as the computer itself) and target market of home computer users, BASIC's file commands defaulted to the tape drive (device 1). In order to load a file from a commercial disk, the following command must be entered:
  LOAD "*",8,1
  In this example, '*' designates the last program loaded, or the first program on the disk, '8' is the disk drive device number, and the '1' signifies that the file is to be loaded not to the standard memory address for BASIC programs, but to the address where its program header tells it to go—the address it was saved from. This last '1' usually signifies a machine language program.
  Not long after the 1541's introduction, third-party developers demonstrated that performance could be improved with software that took over control of the serial bus signal lines and implemented a better transfer protocol between the computer and disk. In 1984 Epyx released its FastLoad cartridge for the C64, which replaced some of the 1541's slow routines with its own custom code, thus allowing users to load programs in a fraction of the time. Despite being incompatible with many programs' copy protection schemes, the cartridge became so popular among grateful C64 owners (likely the most-widespread third-party enhancement for the C64 of all time) that many Commodore dealers sold the Epyx cartridge as a standard item when selling a new C64 with the 1541.
  As a free alternative to FastLoad cartridges, numerous pure software turbo-loader programs were also created that were loaded to RAM each time after the computer was reset. The best of these turbo-loaders were able to accelerate the time required for loading a program from the floppy drive by a factor of 20x, demonstrating the default bus implementation's inadequacy. As turbo-loader programs were rela
caption: Commodore 1541C Floppy Drive, 2nd model
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