The Commodore 1571 was arguably Commodore's finest 5¼" floppy disk drive, having the ability to use double-sided disks without the need to remove them and turn them over ("flippy disk") as in the previous Commodore drives on which it was based (Commodore 1541, 1570).

The 1571 was released to match the Commodore 128, both design-wise and feature-wise. The later C128D had a 1571 compatible drive integrated in the system unit. Permitting double the online capacity of the 1541, a disk formatted for/with the 1571 could hold 1,328 256-byte blocks of data (i.e., 332 KB). A fundamental flaw, however, was the fact that the number of files on a disk was still limited to 144, like on the 1541.

Like the single-sided 1570, the 1571 offered a data burst-mode when used with the C128, giving significantly better performance than the 1541. The 1571 could also closely emulate the 1541 for compatibility with copy-protected software titles. When used with a Commodore 64, the 1571 came up in 1541 compatibility mode by default and it was necessary to type a software command to switch the drive to double-sided 1571 mode.

The 1571 was noticeably quieter than its predecessor and tended to run cooler as well, even though, like the 1541, it had the power supply inside the unit (other contemporary Commodore drives, like the 1541-II and the 3½" 1581, came with external power supplies). The embedded OS in the 1571 was CBM DOS V3.0 1571, an improvement over the 1541's V2.6.

Unlike the 1541, which was limited to GCR formatting, the 1571 could do both GCR and MFM disk formats. A C128 in CP/M mode equipped with a 1571 was capable of reading and writing floppy disks formatted for many CP/M computers; specifically, the following formats:

• IBM PC CP/M-86*
• Osborne 1
• Epson QX10
• Kaypro II, IV

With additional software, it was possible to read and write to DOS*-formatted floppies as well. Numerous commercial and public-domain programs for this purpose became available, the best known being SOGWAP's "Big Blue Reader".

(* CP/M-86 and DOS files could be read in order to perform data file exchange only, as the C128 with its 8502 and Z80 CPUs wasn't equipped to run 8086-based software, of course.)

References

• Ellinger, Rainer (1986). 1571 Internals. Grand Rapids, MI: Abacus Software (translated from the original German edition, Düsseldorf: Data Becker GmbH). ISBN 0-916439-44-5.