Author: Robert Hyatt
Date: 07:44:52 08/14/01
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On August 14, 2001 at 07:26:22, Adam Oellermann wrote: >On August 14, 2001 at 04:11:58, Jeremiah Penery wrote: > >>On August 14, 2001 at 00:44:43, Slater Wold wrote: >> >>>Oh, and like the MS clip said, there are programs that when run under Windows 98 >>>or ME will USE a 2nd CPU. But they are not going through the OS. CAD and even >>>the deep programs will use a 2nd CPU under Windows 98 and ME. >> >>This is wrong. Win9x/Me do not even acknowledge that a second processor exists. >> Since in this case the program can't know more than the OS, it is impossible >>that a program can use both CPUs under such an operating system. Really, it >>just does not work. > >Before I start, I don't know either way, having never tried an SMP box on a >silly operating system. However, the notion that software is limited to what is >exposed by the OS is surely incorrect. Actually it isn't. Programs run in a "user mode" on the cpu which prevents them from doing certain operations that would tend to make security impossible or would tend to affect other programs in a negative way. IE a program can't directly read/write a disk drive, it has to go through the O/S file management stuff to enforce file permissions. A program can't store anywhere in memory it wants or it could/would corrupt other programs. Of course a user can (in unix) run as "super-user" and get the processor into a privileged mode and do the above things. But with the very likely affect that the machine will crash and burn at some point. A user-mode program gets whacked if it does something illegal. A kernel-mode program brings the whole machine down if it does something illegal. > It seems to me that low-level software >can choose to use OS services or bypass them. Slater may be talking about >software simply bypassing OS services in this instance. It may not be easy, but >it should surely be *possible*. Bypassing the O/S _must_ be impossible. Otherwise it offers no protection/ security between the programs that are running concurrently. As a result, it would be unreliable and unstable. The antithesis of what an operating system is supposed to be. > >- Adam
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