Archiving disks to tape? (late 1970s)

[Linards Ticmanis <ticmanis@gmx.de>]

Hello,

in the Apple II entry of the German Wikipedia, somebody has suggested
that cassette tapes continued to see some use on the Apple II for a
while after the Disk II was available, namely as a backup medium for
disks when those were still rather expensive. It says that "with special
software", up to 30 floppies could be archived to one cassette. This
would indeed have been quite a bit less costly than buying another 30
disks for 5 Deutsche Mark apiece.

However I have never heard of such backup software, which I assume would
need to store whole-disk images to the tape, in whatever format. Did it
actually exist back in the day?

-- 
Linards Ticmanis