Random Access Tape 2450
Random Access Tape 2452
Let me throw a bit of cold water on this part of the thread. DDS drives write an END OF...
Continuous tape - one of the options we have been discussing - has no "end". For continuous tape, it's 1-2.
Random Access Tape 2451
Charles Shannon Hendrix I validated this feature on IBM 2420 9 tracks in about 1968 plus 1. When you wrote the tape using the standard OS access method, 2 file marks were written after you...
Whether a reel-to-reel tape device can seek backward is a matter of implementation. If it can't, then when a tape is positioned at the halfway point, the average seek distance is the average of 1-4 (new position is ahead of current position) and 3-4 (new position is behind; must rewind and seek forward), so it's 1-2. Whether such implementation details matter in this sort of discussion is an open question.
(Note that I incorrectly stated in another message that reel-to-reel tapes that can't seek backwards have worse than 1-2 average seek distance. They're worse than tapes that can seek backwards, but you're correct that the difference is 1-3 versus 1-2, not 1-2 versus whatever I thought it was.)
(Of course, in practice, the position you want to be at is always sufficiently far away that you'll be annoyed at having to wait for it.)
Art is our chief means of breaking bread with the dead ... but the social and political history of Europe would be exactly the same if Dante and Shakespeare and Mozart had never lived. -- W. H. Auden