Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!rutgers!sunybcs!ugkamins
From: ugkamins@sunybcs.uucp (John Kaminski)
Newsgroups: comp.sys.amiga
Subject: Re: Leaving Computer On
Keywords: Amiga, Continuous, Turned on, Running
Message-ID: <5277@cs.Buffalo.EDU>
Date: 15 Apr 89 02:27:59 GMT
References: <7684@phoenix.Princeton.EDU> <11984@ut-emx.UUCP> <13123@louie.udel.EDU>
Sender: nobody@cs.Buffalo.EDU
Reply-To: ugkamins@sunybcs.UUCP (John Kaminski)
Organization: SUNY/Buffalo Computer Science
Lines: 30

In article <13123@louie.udel.EDU> new@udel.EDU (Darren New) writes:
>I have heard, as an unsupported rumor, that the Amiga video chips
>may incur damage if the video is turned off while the computer
>is on.

Slight chance of a voltage spike coming thru the monitor cabling.  I suppose
this is akin to shutting down of a refrigerator motor someplace close to your
computer while having it on.  I think it is about the same risk that is incur-
red if you leave the disks in the drive(s) while powering up/down.  Sure, there
is a real slight chance that a pulse will go thru the write head, but that
chance, in my opinion, is rather slim.

Oh, BTW, I was wondering if write protect is harware or software enforced.  I
had the ("lowly") Timex/Sinclair 2068 and something called a MikroDrive for
it (that used special little continuous loop tapes).  I was feeling a little
adventurous (sp?) one day while fooling around with the port.  I figured that
outputting 255 would set all the bits in that particular register, thereby
activating the drive motor (the desired action).  HOWEVER, that also turned
on the write bit too.  Control was somewhat like the cassette port, in that
you were responsible for generating the written bit pattern by toggling the
status of that bit on that port.  Much to my dismay, I had a completely blank
tape after doing what I wanted.  The write protection was strictly managed in
software by reading the status of another port, which had a bit of that port
connected to a lever switch.  Without trashing one of my disks, is it possible
to program the disk DMA, start the motor, etc. and write the disk with the
tab on "protect?"  I am pretty sure on IBM-PC drives, the controller chip
refuses to do it and puts a write-protect into its status register, thereby
making write-protect more-or-less hardware enforced.  The only way you could
do it is to change the firmware or microprogramming of the controller.
What say you in netland?