Date: Mon, 7 Dec 1998 14:33:57 -0800 (PST)
From: "Steven M. Schultz" <sms@moe.2bsd.com>
Message-Id: <199812072233.OAA07800@moe.2bsd.com>
To: PUPS@minnie.cs.adfa.edu.au, SHOPPA@trailing-edge.com
Subject: Re: 9-track tape interfaces
Sender: owner-pups@minnie.cs.adfa.edu.au
Precedence: bulk

Tim -

	Howdy.

> I'm pretty sure that 2.11BSD properly handles TU81 density select
> in its TMSCP driver.  (Steve, can you confirm this?  I know you've
> made some effort to get write caching to work with TU81's over the years!)

	Indeed it does.  However TMSCP only defines 800,1600 and 6250 so
	on the quad density drive I have the 3200 setting must be selected
	manually on the front panel of the tape drive.

	Also the 'enable cache' works fine and makes a dramatic difference
	on a TU81+ attached to an 11/44.  The 'cache enabled' setting is
	sticky across open/close cycles so that you set it once manually
	when the first reel is loaded.  This was done to avoid having to
	modify dump/restore/tar/etc

> In any event, remote density selection/reporting is largely a
> frill, as any drive/controller combination that I ever used let you
> explicitly select it with a physical button or a switch and displayed
> the current selection in some useful way on the drive.

	Quite so.  Eons ago the one Cipher drive supported 800/1600 operation
	but the controller (TM11 clone) did not - you just made sure to
	select the density on the front panel when loading the tape

	Steve