Article View: comp.os.msdos.programmer
Article #1764Re: Programming the Mouse
From: Bernie Roehl
Date: Thu, 02 Aug 1990 14:03
Date: Thu, 02 Aug 1990 14:03
14 lines
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1269 bytes
In article <1990Jul31.193800.18227@uokmax.uucp> gene@uokmax.uucp (Gene E. Johannsen) writes:
>Anyway, I found my problem. It is the 'int 21h' that freezes it. I honestly
>don't know why.
It's because DOS is not re-entrant. You may be in the midst of a DOS call
when a mouse interrupt comes along; you call DOS again from your handler,
and since DOS has only one internal stack you overwrite what was there
previously. Your call completes, you get your *, then the handler returns
to a clobbered stack and your system goes to Sudbury.
--
Bernie Roehl, University of Waterloo Electrical Engineering Dept
Mail: broehl@watserv1.waterloo.edu OR broehl@watserv1.UWaterloo.ca
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<1990Jul30.182430.7493@uokmax.uucp> <34725@ut-emx.UUCP> <1990Jul31.193800.18227@uokmax.uucp>Show Full Headers
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Path: arc1-ca.pugleaf.net!utzoo!attcan!uunet!decwrl!sdd.hp.com!samsung!sol.ctr.columbia.edu!cica!iuvax!maytag!watserv1!broehl From: broehl@watserv1.waterloo.edu (Bernie Roehl) Newsgroups: comp.os.msdos.programmer Subject: Re: Programming the Mouse Message-ID: <1990Aug2.140351.4185@watserv1.waterloo.edu> Date: 2 Aug 90 14:03:51 GMT References: <1990Jul30.182430.7493@uokmax.uucp> <34725@ut-emx.UUCP> <1990Jul31.193800.18227@uokmax.uucp> Organization: University of Waterloo Lines: 14