Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!julius.cs.uiuc.edu!rpi!clarkson!grape.ecs.clarkson.edu!levericw From: levericw@cheetah.ece.clarkson.edu (Walden Leverich) Newsgroups: comp.os.msdos.programmer Subject: Re: Increasing #task switches per second (> 18.2), help Message-ID: Date: 12 Dec 90 18:48:52 GMT References: <4348@dnlunx.pttrnl.nl> <75778@iuvax.cs.indiana.edu> <76399@iuvax.cs.indiana.edu> Sender: @grape.ecs.clarkson.edu Organization: /home/levericw/.organization Lines: 40 In-Reply-To: bomgard@iuvax.cs.indiana.edu's message of 4 Dec 90 19:59:51 GMT In article <76399@iuvax.cs.indiana.edu> bomgard@iuvax.cs.indiana.edu (Tim Bomgardner) writes: Tim> filetp@dnlunx.pttrnl.nl (Peter Filet) writes: Tim> >I am developing an Operating System, in the Protected Mode of the i286 Tim> >processor. Tim> > (wants a faster system clock) Tim> This is actually very easy to do. The idea is to hook the clock Tim> tick interrupt,keeping the original vector and substituting your own Tim> handler. Then, if you Tim> want, say, a 4X clock rate (72.8/sec), you call the original handler every Tim> fourth tick. The rest of the OS has no idea anything has Tim> changed..... Very interesting. But wrong. Considering that your interrupt timer will be called once every 1/18.2 seconds. Now if your pass that tick onto the OS every fouth time, then the OS gets 1/4 of the clock *NOT* 4X the clock. Tim> from its point of view, nothing has. Tim> I'll be happy to send the .asm code that does this to anyone who wants it. Tim> Academic types can usually tell you why you can't do something. Tim> Commercial software developers can usually tell you how to do it Tim> anyway :) Academic types in the CompEng field will explain why it is impossible. -Walden -- --------------------------------------------------------------------------- Walden H. Leverich III | Inet: levericw@clutx.clarkson.edu ECE Dept. | CServ: 73237,2212 <- checked weekly Clarkson University | SnailMail: Software Solutions | PO Box 763 | Potsdam, NY 13676-0763 #include --------------------------------------------------------------------------