Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!apple!well!mccarthy
From: mccarthy@well.sf.ca.us (Patrick McCarthy)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Ctrl C Echo
Message-ID: <16717@well.sf.ca.us>
Date: 16 Mar 90 04:15:03 GMT
References: <3253@optilink.UUCP>
Reply-To: mccarthy@well.UUCP (Patrick McCarthy)
Organization: Whole Earth 'Lectronic Link, Sausalito, CA
Lines: 20

In article <3253@optilink.UUCP> cramer@optilink.UUCP (Clayton Cramer) writes:
>
>I haven't had much luck disabling ^C echo under DOS using signal, 
>while still keeping the ^C interrupt useful to my application
>program.  I presume that my only real hope of disabling the built-in
>^C echo is by grabbing the keyboard interrupt, and filtering out
>^C at the ISR level.  Has anyone already done this?

Yes, and yes.  The general method is to filter interrupt 0x1B (the
vector called by the BIOS when CTRL-BREAK is hit), and interrupt 0x16
(the interrupt DOS invokes when it is waiting for a keystroke).
The logic in the 0x1B handler is simple (set a global variable and
return), but the logic in the 0x16 handler gets a bit wierd.
I wrote a program using a commercially available library to provide
the ISR support, but it would be real easy to convert it to the MSC
or Turbo C "interrupt" type function.  Please E-mail me if you want
details on how to get the source.

Pat McCarthy
mccarthy@well.uucp