Commodore 1541

The Commodore 1541 was the best known floppy disk drive for the Commodore 64 home computer. The 1541 was a single sided 166 kilobyte drive for 5.25" disks. Converting to "flippy disks" (disks that could be turned over) would give another 166Kb. Each 166Kb was split into 664, 256-byte 'blocks'; the file system made each block its own cluster.

The disk drive used Group Code Recording[?] and contained a 6502 processor as a disk controller. The drive's built-in operating system was CBM DOS v2.6. Most notably, the DOS limited the number of files per disk to 144 regardless of the number of blocks there may have been free on the disk because the directory was of a fixed size, and the file system did not allow for subdirectory.

The drive-head mechanism was notoriously easy to mis-align, and had a tendency to make a 'machine-gun' rattle when out of alignment or formatting a new disk. Some people even wrote code to vibrate the head at different frequencies to play tunes.

The 1541 used a bit-serial version of the IEEE 488 parallel protocol. The simple protocol that the built-in DOS used supported only about 300 bytes per second. Some third-party speed-ups could transfer about 4 kilobytes per second over the interface, and some "fast loaders" managed up to 10 kBps.

The Commodore 1570 was an upgraded 1541 for use with the Commodore 128.

See also: Commodore 64, Commodore 128, Commodore 1540[?], Commodore 1570, Commodore 1571

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Based on material from FOLDOC, used with permission.