The first computer that I recall seeing in person was an Olivetti P603 at my Dad’s office. I was about 12, early senventies. 
Seen here is a stock photo from Olivetti. My dad’s version didn’t have the drawer storage cabinet seen on the left that I recall. An electric typewriter console occupied the central operator position. On the right was a calculator type console which also served as the programming unit. On this same programming unit was a calculator size paper printer and also a magnetic strip reader/writer. Not seen in this stock photo, but below the desk level and to the right of the operator was a tape cabinet unit. One would place a tape cartridge into the unit positioning it onto the keyed motor spindle and then operate a hand lever to engage the tape into the electronics of the tape unit. Each tape contained it’s own read/write head. The tape itself was a single length endless loop configuration as pictured here. The tape cartridge dimensions were about 7″ by 6″ by 2″. 
The usable tape is visible in through the smoke gray plastic with the exception of a length that ran from this oval area to the read/write head seen at the top through the “dimpled” portion. The tape ran through a few capstans and a tensioner around the perimeter. The tape itself had 4 tracks. I have since forgotten the density of the tape, but I don’t believe each track was more than 4k roughly, for a total of approximately 16k. For a bit of fun, one could take the cartridge by itself, hand-rotate the keyed receptor on the back, and watch the tape “slowly” move through its path. As a 12 year old, I thought it was magic that the tape didn’t end up in knots. So what could you do with this whole thing? Well, it could be used as a typewriter. You could also use it for it’s calculator though I never saw it used that way myself. Then with the magnetic cards (about 2.5″ by 8 or so inches, double sided) and/or with the tape unit, one could read/write/run programs. The programs could output onto the typewriter. There was no screen. And before I forget, it weighed a “ton”. In 1979 he still had this boat anchor running parts of his office. And that year, being a computer science major and believing I could do anything with a computer, I wrote a structural heat-loss program for him on this unit. It was worse than coding in APL. Well, not really. Just to wrap up the nostalgia a bit, in summary, if one used enough of the calculator paper, one could wind it back up tightly and then pull it from its center, making a real neat paper sword for that child still in oneself – fun and no worries.
Ramblings