Re: tapefs

Michael Shields (shields@crosslink.net)
18 Sep 1998 06:24:20 +0000


In article <Pine.LNX.3.95.980917084046.1062B-100000@chaos.analogic.com>,
"Richard B. Johnson" <root@chaos.analogic.com> wrote:
> The TU-77 reel-to-reel counted tape-marks in hardware. This created a
> problem when you first physically mounted a brand-new tape. It would zip
> back and forth on its own, trying to find out where it was. If there were
> no file-marks, it would report "position-lost" which would confuse

DAT audio tapes contain a subcode which, among other things, includes
an absolute-time counter. This allows you to know that, say, the data
you want starts at time 1:07:04.14, and have it be consistent across
decks. The absolute time can be read (if you have clean heads) even
during fast-forward and rewind which occur at over 100x normal speed.
If you insert a unrewound tape into a deck, it will immediately read
the subcode to find out its position. It is a shame that DAT data
drives don't have a feature like this.

-- 
Shields, CrossLink.

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