On Thu, Jan 3, 2013 at 4:20 AM, Jim Lemon <j...@bitwrit.com.au> wrote: > On 01/03/2013 12:57 PM, dmccunney wrote: >> On Wed, Jan 2, 2013 at 7:57 PM, Jim Lemon<j...@bitwrit.com.au> wrote: >> >>> If there was a Linux kernel in which the user could turn off everything that >>> isn't in DOS, that would be a way out. >> >> If you could turn off everything that *isn't* in DOS, you might have >> fun running the Linux kernel. You run DOS in an emulator on top of >> Linux because you can't *get* DOS to run native on that hardware. >> Drivers are needed that don't exist. >> >> What you probably want is a flavor of Linux modified for use in an >> RTOS, where a user process can preempt the kernel itself. >> > Exactly. I intend to try out RTLinux at some point.
"Real time" simply means "guaranteed to respond to an external event within a specified period". What time period is required? >> But on modern hardware, "other time-critical programs that will carve >> out slices of CPU time" are likely a "Who cares?" issue. Commonly >> used hardware is orders of magnitude faster than the machines DOS was >> made to run on, and there are cases like games where you might >> specifically *want* to steal CPU slices, because otherwise your game >> runs *too* fast and is unplayable. . >> > I have had to do this once, when writing an assembly code driver for a > digital rotation encoder. The read cycle had to be slowed down by a > specified number of NOPs to allow the register to load. The problem is > that when a program is monitoring response devices such as the mouse and > keyboard and presenting an animated display to the user, even a > millisecond lost to some other program is a disaster. As I can often see > the system "blink" on modern PCs running Windows and even Linux, I'm > reasonably certain that I can't trust them to be accurately recording > reaction times. One of my colleagues thought that she had solved the > problem by buying an expensive test battery until I showed her the > "uncertainty" factor that came with every response recorded. How accurately do you *need* to be recording reaction times? For that use case, I'm not sure I'd try to run DOS on top of Linux, even with a Linux version modified for RTOS usage. The best option might be custom monitoring software running directory on the RTOS, without DOS in the loop. > Jim ______ Dennis https://plus.google.com/u/0/105128793974319004519 ------------------------------------------------------------------------------ Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, CSS, MVC, Windows 8 Apps, JavaScript and much more. Keep your skills current with LearnDevNow - 3,200 step-by-step video tutorials by Microsoft MVPs and experts. ON SALE this month only -- learn more at: http://p.sf.net/sfu/learnmore_122712 _______________________________________________ Freedos-user mailing list Freedos-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freedos-user
