On 2014-05-18 05:10, Rich Alderson wrote:
Date: Sat, 17 May 2014 18:26:33 +0200
From: Johnny Billquist <[email protected]>
On 2014-05-15 23:10, Clem Cole wrote:
In 9-track world, the end of each file is mark as a single meta record
(tape mark), Two in the row marks end-of-tape. So the when you write
a take the driver check to see if its at start of tape and if not, has
to backs up over the last tape mark and then start writing. On close it
writes 2 tape marks.
The two tape marks for logical EOT is a convention, and not all software
adhere to it. But in general, right. I think someone else mentioned it,
but it's worth pointing out that for ANSI labelled tapes, the tape marks
are not used this way, for example.
Actually, tape marks are used in just this way on ANSI and IBM/EBCDIC tapes.
The "headers" and "trailers" of labeled tapes are physically separate files,
with the physical demarcation of tape marks and interfile gaps and all that
telling the OS where to find them.
Right. And logical EOT is marked by a block saying so, and not by two
consecutive tape marks... :-)
You might hit two consecutive tape marks in the middle of an ANSI
labelled tape. (Not common, but definitely possible.)
Johnny
--
Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: [email protected] || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol
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