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Path: utzoo!watmath!clyde!cbatt!neoucom!wtm
From: wtm@neoucom.UUCP (Bill Mayhew)
Newsgroups: net.micro.apple
Subject: Re: Apple //e Interrupts
Message-ID: <250@neoucom.UUCP>
Date: Sun, 10-Aug-86 13:06:38 EDT
Article-I.D.: neoucom.250
Posted: Sun Aug 10 13:06:38 1986
Date-Received: Tue, 12-Aug-86 01:12:28 EDT
References: <283@ski.UUCP> <3222@utcsri.UUCP>
Organization: Northeastern Ohio Universities College of Medicine
Lines: 36
Summary: No more drive brrrraaattt!


[Watt's my line...]

Hi,
	The Brrrrraaattt! that apple disk drives make has to be one of
the worst sounds on earth!  Of course, other than at start up, that
noise is usually indicitive that major loss of data eith just has
or is about to happen.

	About 6 mo. ago, I bought some cheep-o 1/2 height disk
drives from JDR.  I think they're called "BAL 500".  The drives are
built around a Teac mechanism that that has track zero sensors and
various other goodies.  One neat feature is that when the drive
reaches track zero, the internal LED sensor cuts off any further
stepping.  No more Brrrrraaattt!  The other neat feature these
drives have is the write-protect LED sends its pulse to a
differentiator and one-shot that turns the spindle motor on for a
few seconds.  When disks are inserted, they turn on the motor
briefly to assist in alignment of the diskette-- very nice touch!
I really appreciate this, since media positioning is easy to botch
on the newer "duodisk"; I really miss the old Shugarts!

Another nifty device is the "BAL" drive controller.  At boot time
the controller examines for either DOS 3.3 format or 3.2 format and
switches in the appropriate control and decoder ROMs.  It uses a
latch that can not be accessed from the CPU to do the setting of
the ROM, thus the controller functions well even with copy-proof
software.  We like this, as we still have a lot of old software
floating around, and this eliminates the need for the "boot13"
diskette.

Bill Mayhew
Division of Basic Medical Sciences
Northeastern Ohio Universities' College of Medicine
Rootstown, OH  44272  USA   (216) 325-2511
(wtm@neoucom.UUCP)