In article <ec771527c0a0c99d33c9adc43d6bb32d at lunar-tokyo.net>,
Daniel Seagraves <dseagrav at lunar-tokyo.net> writes:
A block is a sequence of tape frames. Those can be 7
or 8 bits wide
depending on your hardware. Blocks have length, and can vary in length
from block to block. You can have a small descriptor block between long
data blocks on the tape, where the small block describes what the next
large block contains, and so on. You can tell if a block is a
descriptor by its length, or looking for a magic number at the start of
the block, or whatever.
OK, this seems to indicate that there is a well defined mapping
between tape frames and bytes. Since a block is a sequence of tape
frames, that implies that blocks are well mapped to a sequence of
bytes. I guess I'm still missing something that magtape solves that a
stream of bytes doesn't solve.
My understanding is that the hardware tape interface just delivers a
sequence of tape frames without any additional interpretation and that
its the driver/OS/whatever that interprets the tape frames into some
larger structure.
Tapes also have file-marks.
How is that represented?
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