Well, there were two types of MiniCD; the ones that ran in the PSP inside the Sony custom cartridge, and the ones that were approx 2.5" and used for drivers which technically ran in any CD player but in general, wrecked irrepairably, any type of CD player - once they went in, they never came out.
As an aside to storage media, I ran a recording studio for over 20 years. The most interesting thing I realized in the whole time was that our assumptions as to what is "safe" storage are inevitably flawed:
- all music was originally stored on magnetic reel-to-reel tape, lets say
- after 20-40+ years, it transpired the tape stuck to itself, demagnetised, decomposed, it wasn't valid
- everything was transferred to DAT tape.....but nobody supported it and you literally couldn't buy players - but A-DAT was valid
- except A-DAT was dropped fairly shortly afterwards
- we were all stunned by what you could fit onto CD, then DVD5, then DVD9
- then we discovered that 2-5 years later the discs would not read
- but we had hard disc now, so everything was OK!
- except we've all had a hard disc failure. So just RAID it, or get two - put one offline.
- then your offline gets flooded, burnt in the sun, dusty, or mouldy
- so now, we are in a unique position. With 40-60Gb of high quality audio for a 24-track audio master, where do we store it?
- what, in fact do we know?
There is still no long-term solution for this! Hard disc hasn't been round long enough to prove itself against 2-4" tape. Long-term storage is actually not something we have any solution to - save to keep moving the media from place to place - but thats impossible if you wish to keep your audio in the analogue realm....