I used audio cassettes for reading and storing for years (1977-1986). Once everything was setup with the right levels and azimuth, it was very reliable and gave enough ime to drink coffee and thinks while waitingfor it.!.
KIM-1 audio, two identical tape recorders out of a hifi system (junk store), motor on/off controlled by the KIM-1, one for reading, one for writing. Of course everything of value stored twice on a tape and also on another tape.
Micro ADE as 'operating system'. I wrote books and much software this way. Normal FE tape. Tapes from e.g. 1982 were readable via a PC sound card (and a working tape recorder, the old ones were unusable. the belts all 'melted') in 2006, when I archived the tapes and got rid of the cassette tapes.
The KB9 we use nowadays came from one of my tapes, as most of the KIM software I have on my website.
As Jim says, reading and writing with a PC sound system to the KIM audio just works fine now, with the same level adjustments wizardry. No way I will add a tape recorder and tapes to my setup now!
So the KIM-1/PAL-1 audio system is still nice to have.