These tapes were used to store data for mainframe computers. In Poland they were made by Stilon factory, which made other magnetic media too - even floppy disks.
|Manufactured by: Stilon, Pyral|
|Type: Magnetic media|
PT-3 was common tape storage device used with Odra 13xx computers. It was connected by serial channel and allowed theoretical maximum 96kb/s transfer speed.
Capacity of one reel varied, there were few sizes of reels and few densities allowing to store 8-16MB of data on large reel. Theoretically it was possible to put more, but poor quality of tapes caused many errors.
PT-3 used 2 vacuum chambers to compensate reel inertia and keep the fragile tape in one piece during quick spin direction changes.
Here are some photos from catalogues and magazines:
Another interesting photo: Facit Carousel - device consists of 64 replaceable drums, each wound with magnetic tape. It's used as storage and temporary memory.