Certron C-60 cassettes. If you remember those, lmao you are OLD.
When I was a kid there was the tail end of a BBC Radio tech program that broadcast what was essentially early GNU / Open source code over the radio, what you did was connect a normal casset recorder to a radio, wait for the 5 pips to finish and hit record it was then encoded onto the tape and it could be read as data when used by a BBC Micro Computer or something else that could read BBC Basic (or a few other forms of BASIC), and those tapes being passed around as far as the mid 90's.
There was also a time where you could buy a set of clippers to make Floppy disks double sided (for young kiwi's before the 3.5" floppies they where single sided) it had two cutting edges one for the top and one for the lock and had preset gauges to make it work flawlessly.
I can recall installing a game that was shipped on 3.5's but the installer wasn't updated from a 5'' floppy and it said Turn Disk 1 to side B, I'm of a age not even all that old (I'm 36) where modern data density still blows my mind, I can recall a time where a basic flight sim of 24 floppys was a struggle to hold in your hand and required, a 300 page manual and Boot Disk to play with about 50mb of data in total, now I can buy several terabytes of disks and hold them in my hand.
It blows me away how far we have come in technical ability, and portability even in the time I've been alive, I mean the first Phone my parents had was a Rotary Dial and for a lot of my youth the main concern my folks had was make sure I had 20p to call home as a kid and a lot of public phones where still Rotary Dial (but getting swapped out) and now I'm struggling to think of where my nearest public phonebox is that isn't a single number phone in a shop or trainstation to call a Taxi. Hell there is a Major Bus station I know that is also a Major trainstation that has a Vending machine that's gone from selling Calling Cards to Fully charged phones with a Pay as you go airtime credit, Sim Cards and other things like power banks.
I'll give you another example, I can recall a period of time where if you applied for a job a tech job you where expected to send your CV in on paper and on floppy disk, as the company didnt have a LAN or shared internet connection, it seems that in the space of a year everyone got the internet and specifically asked to not have paper applications.
Hell before MMO's I can recall MUDS, you had to dial into them play your turn and then wait for the next person to do the same etc and there being another place to dial in to collect you messages and stats etc if you where lucky.