Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!think.com!samsung!umich!sharkey!clmqt!steve
From: steve@clmqt.marquette.MI.US (Steve Lasich)
Newsgroups: comp.sys.ibm.pc
Subject: PrtScr > /dev/null (was Re: **** Ctrl-P)
Message-ID: <1991Jun1.165118.5777@clmqt.marquette.MI.US>
Date: 1 Jun 91 16:51:18 GMT
Sender: steve@clmqt.marquette.MI.US (Steve Lasich)
Lines: 51
X-bbs-room: IBM Worldwide (room #36)

gintera@cpsc.ucalgary.ca (Andrew Ginter) writes:

>I had the same problem and solved it by using the "mode" command to
>redirect printer output to one of the COM ports.  I believe I have it
>reconnected to COM1:, which has a modem always attached and always
>powered up.  I don't know if that makes a difference as to whether or
>not the trick works.  When I'm using a terminal emulator, ^P is caught
>by the emulator and is sent down the line as usual.  When I'm not
>using an emulator, the modem doesn't seem to mind getting the odd
>screenful tossed at it.

>Andrew Ginter, 403-220-6320, gintera@cpsc.ucalgary.ca

Hmmmm.  What happens if you hit PrintScreen while you are 
using your favorite newsreader?  :-)

Peter Norton explains in one of his books that DOS uses location
0040:0078 to determine how long it will wait for LPT device timeouts.

It turns out that if you put a zero in that memory location, you 
will never again hang your computer due to accidentally invoking
printer output in the absence of a printer or when your printer
is turned off.

I wrote a 14 byte program that I run from my AUTOEXEC.BAT which
twiddles the timeout count number every time I boot up.  I just
looked at the program in debug.  It's called TIMEOUT!.COM.  This
is what it looks like in debug:

	MOV	BX,0040
	MOV	DS,BX
	MOV	BX,0078
	MOV	AH,00
	MOV	[BX],AH
	INT	20

All numbers are in hexadecimal.  There, boom.  For a test I just
hit the PrintScreen key and kept on typing.  The time-lag as the
cursor popped up the the top of the screen and returned to 
where I was typing was barely noticeable.

At work, I am responsible for 65 PCs of which 59 are not connected
to printers.  I have TIMEOUT!.COM in the autoexec of every one
that is not connected to a printer.  It solves a lot of problems.

I can't keep up the volume of postings in this newsgroup so please
cc: any followups to one of the following addresses.

----
Steve Lasich, Microcomputer Lab Coordinator          acsl@nmumus.bitnet
Northern Michigan University                steve@clmqt.marquette.mi.us