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No. Sorry. My comment was from a conversation I had in the mid-80's with a couple of field service reps who worked the site and couldn't believe it themselves.

No. Sorry. My comment was from a conversation I had in the mid-80's with a couple of field service reps who worked the site and couldn't believe it themselves. The magtapes used to hang on row after row of metal racks. The operators would retrieve the tapes, hold them on their forearms, and bring them back to what were usually a centralized set of tape drives. Here's an offset into a video showing what it typically looked like. [0] The narrator refers to a "search tape" used to retrieve the person's information. The tape had to be retrieved from the racks. The sheer weight and overall length of the rows/racks meant the rooms were often lower level with vinyl flooring over concrete (raised tile later). Imagine walking up and down for an 8-hour 5pm-1am shift. Not difficult to imagine skates. Here's another video with a good representation of how it worked. [1] As I have come to accept, the mid-80's was pre-everything. Deliberate change takes time. [0]: https://youtu.be/Iddrm7mHPrY?t=111 https://youtu.be/Iddrm7mHPrY?t=111 [1]: https://www.youtube.com/watch?v=Cwj6pfhWBps https://www.youtube.com/watch?v=Cwj6pfhWBps

markus_zhang 5y ago
Thanks a lot for the links!
dtgriscom 5y ago
A few seconds after your starting point in that first video, you can see a loop of tape vibrating back in forth in a rectangular channel. That's a vacuum column, with a (mild) vacuum pulling the tape loop to the right. This lets the servomotors that move the tape past the heads start and stop rapidly, while the heavy tape reels can spin up and down more slowly. See how the vibrating loop passes back and forth across a hole in the middle of the column? That's a pressure sensor. As the loop moves across the hole, the pressure in the hole changes, telling the drive whether it's time to reel in or dispense more tape. More info: https://en.wikipedia.org/wiki/9_track_tape https://en.wikipedia.org/wiki/9_track_tape
- johnohara 5y ago
  IIRC, once it had a stable hold on the tape the drive would begin reading in an effort to locate the start of the data. On old tapes this might take a number of retries with the drive rewinding, reading, rewinding, reading... etc. Sometimes it didn't work at all and you were stuck with a bad tape that needed special attention.

markus_zhang 5y ago

Thanks a lot for the links!

dtgriscom 5y ago

A few seconds after your starting point in that first video, you can see a loop of tape vibrating back in forth in a rectangular channel. That's a vacuum column, with a (mild) vacuum pulling the tape loop to the right. This lets the servomotors that move the tape past the heads start and stop rapidly, while the heavy tape reels can spin up and down more slowly. See how the vibrating loop passes back and forth across a hole in the middle of the column? That's a pressure sensor. As the loop moves across the hole, the pressure in the hole changes, telling the drive whether it's time to reel in or dispense more tape. More info: https://en.wikipedia.org/wiki/9_track_tape https://en.wikipedia.org/wiki/9_track_tape

johnohara 5y ago
IIRC, once it had a stable hold on the tape the drive would begin reading in an effort to locate the start of the data. On old tapes this might take a number of retries with the drive rewinding, reading, rewinding, reading... etc. Sometimes it didn't work at all and you were stuck with a bad tape that needed special attention.