Date: Mon, 26 Aug 1996 12:08:40 -0700 From: Raymundo Vega Aguilar <rvega@cicese.mx> To: KUMAR@BOGPO1.CO.unisys.com Cc: questions@FreeBSD.ORG Subject: Re: Help! Message-ID: <3221F638.417C@cicese.mx> References: <199608260328.XAA29753@james.freenet.hamilton.on.ca>
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> In Email, "Kumar, Rao CO" <KUMAR@BOGPO1.CO.unisys.com> wrote: > > Thanks in advance for your time. I saw your mail id on the Internet. So I am > sending you this mail > and would highly appreciate your help. > I have written a TSR (that runs on MS DOS 6.2) that intercepts the interrupt > 1C (timer interrupt). What I am > trying to do in this interrupt handler is some file i/o (using fopen, fread > and fclose of Microsoft C). Because MS-DOS is a NOT reentrant pseudo-operating system, is very difficult to use file i/o from a TSR program, the solution is somewhat complex (and outside the scope of this list) so if you really want to contnue the proyect, then you have to read: Title: Extending TurboC profesional. Author: Al Stevens ed: Sams Book. (not sure) This is the only one that i have read and has a chapter on the subject. > At times the system hangs. I thought it was due to some conflict in > simultaneous handling of interrupt 21h by the file i/o calls inside my > routine and the foreground application. So I tried to do a check for the > InDOS > flag before proceeding with my interrupt handling routine, but this flag is > always 1 when my interrupt > routine is invoked (even when there is no front end application). > > Probably because the InDOS flag is not being set by the front-end > application, but by your interrupt handling routine. You have to replace the disk I/O interrupt as well. > > 2. Is there any other way to know if MS DOS is executing a 21h interrput ? Yes, but dont remember which one is it. Saludos Raymundo.
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