Reading 1571 disk with 1541

[kopiad]

It was a long time ago I last powered up my C128D. I'm now trying to save the contents on some of the disks. I have a 1541 connected to a PC and have successfully copied some 1541 disks. Is it also possible to read 1571 doublesided disks with a 1541? Simply reading the "B side" of the 1571 disk with StarCommander on the PC does not work (read error)...

[airship]

Depends. There are three different kinds of "double-sided" 1571-compatible disks using the Commodore format. (Let's forget about MFM formatting for this discussion.)

(1) Flippies. These are disks that have one side formatted as a standard 1541 disk, then are flipped in the drive and the second side is formatted. Both 1571s and 1541s will read and write these. The 1571 will have to be in 1541 mode, but it will do this automatically when it reads the disk.
(2) 1571 formatted disks. These store information on both sides, but are formatted and indexed in a single pass on the 1571. The 1541 will read a 1571 disk, but it will ignore side 2. You will see a disk directory for both sides, but any files that exist on side two, or that cross from side one to side two, cannot be read on a 1541.
(3) Two-sided 1571 disks in 1541 format. The 1571 can format one side of a double-sided disk in 1541, and the second side as a separate backwards-1541 format disk. That is, both a 1571 and 1541 can read the first side as a normal 1541 format disk, but only the 1571 can read the second side, because it is written 'backwards' when compared to a 1541 disk. The 1571 reads it without physically flipping the disk. You can issue commands to the drive to change from one side to the other. (Unfortunately, the dual-drive DOS commands don't work with this dual-side mode of the 1571. I wish they did.)

Is that complicated enough for you?

[kopiad]

Thanks for the detailed information. Looks like I found the right forum!