Path: utzoo!mnetor!tmsoft!torsqnt!news-server.csri.toronto.edu!cs.utexas.edu!tut.cis.ohio-state.edu!VAX1.CC.UAKRON.EDU!r3jjs
From: r3jjs@VAX1.CC.UAKRON.EDU (Jeremy J Starcher)
Newsgroups: comp.os.msdos.programmer
Subject: Re: Fixed clock speed on pc?  CLK_TCK == 18.2 is TRUE??
Message-ID: <923@VAX1.CC.UAKRON.EDU>
Date: 22 Dec 90 04:24:52 GMT
References: <15779.2770e40e@levels.sait.edu.au> <2972@pensoft.UUCP>
Reply-To: r3jjs@VAX1.CC.UAKRON.EDU (Jeremy J Starcher)
Organization: U of Akron Computer Center, Ohio
Lines: 28

In article <2972@pensoft.UUCP> lwb@pensoft.UUCP (Lance Bledsoe) writes:
>In article <15779.2770e40e@levels.sait.edu.au> marwk@levels.sait.edu.au writes:
  [ Question Deleted]


>Thats correct!  The clock inturrupt on ANY PC/AT/XT/CloneT is envoked exactly
>every 18.2 times a second.  
>

Watch out!  The normal clockspeed is about 18.2 times a second.

Some programs (GWBASIC) change the clockspeed (thus the clock interrupt)
to four times that speed.  GWBASIC sets up a new handler (INT 8h I think)
to call the old one once every four ticks.  Although this won't matter
to most programs, in a few weird situations it could be nastly.

I know, a minor quip since most people will never care about it.  However
being a low-level programmer makes me very carefull to document any possible
side effects of a feature or function.

PS--- I don't know if that modified clockspeed is a constant state
or weather that only comes in when music is playing...

-- 
--------------------------+---------------------------------------------------
Jeremy J Starcher         !  No programmer programs in LOGO after reaching
r3jjs@vax1.cc.uakron.edu  !  age 14...
r3jjs@akronvm.bitnet      !