From: utzoo!decvax!ucbvax!ARPAVAX:mo
Newsgroups: net.unix-wizards
Title: Re: mag tape ballots counted
Article-I.D.: ucbarpa.1793
Posted: Mon Jul 26 08:45:57 1982
Received: Thu Jul 29 06:47:15 1982

I have a triple-density tape drive and adding support for that simply
exacerbates the already silly state of affairs.  I do have a proposal,
however.  We must keep the current randomness for compatability, but
I think we can implement my proposal concurrently.  The only complication
is that the TU78 driver on 4.1BSD has usurped "mt" as a device name.
That not withstanding,  create a series of devices, call them "tapeN",
one per TRANSPORT, where the N indicates the transport.  These are
minor devices which have the following characteristics.  There is a
transport state table which records the "default" values of density
and "rewindedness" (and anything else we might want to include,
such as file position).  When these "generic" devices are opened, the
transport is conditioned to the saved state.  The existing "mt"
command can easily be extended to specify a density (honored on output,
or input, too, if the drive doesn't autoselect) and the rewind control.
The file position stuff could be added too, but that makes the opens
do more work.  If the filepositioning were added, rewinds might honor
that too.

However, I really think things beyond density and rewindeness should be
done with a process sitting in front of the tapedrive, much like the
VMS tape ACP.  This would let Unix handle "standard labelled tapes"
(in their miriad of standard formats) without the tape driver turning
into another TTY driver.  This would allow specifying a "virtual"
start-of-tape and rewinds proceed back to that point.  It would also
allow embedded file names, as a result of handling labelled tapes.

While this is tricky to do in general, the 4.2 IPC mechanisms should
be up to the task.  I intend to find out when I get my tape!!

	-Mike

PS - plz excuse misspelling of "myriad".  Don't know how to make this
God-forsaken composition program let me edit my text, and Lord knows
there ain't no manual page!!!  Maybe if some of the Netnews creators
had ever used a REAL mail system some of this would be better.
(end of flame)