Random Access Tape 2462

Yes, but those are still random-access devices, because the device can read from non-adjacent points A and B without pbutting over intervening points. I'm talking about the logical "read head" (as in the I-O position in a Turing Machine), not the physical implementation.

Obviously there's room for some disagreement here, but I don't see how the characteristics of disk drives contradict the claim that tape is inherently sequential.

(And, as others have pointed out, it's not necessarily true that a disk-medium device has to read tracking information as it seeks.)

I don't feel that speed is the only difference; I believe there's a qualitative difference between tape media, which by (my) definition are one-dimensional, and planar media such as disks, which by definition are two-dimensional. Note that the physical format isn't the primary criterion here (though obviously it has great influence in practice) - what matters is how the device operates over the medium. Either it has an extra dimension in which to move (and so it can skip intervening "cells"), or it does not.

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A coding theorist is someone who doesn't think Alice is crazy. -- John Gordon