On Thu, 2011-06-02 at 20:04 +0200, Eric Auer wrote: > Hi! > > >> I make diode testers and need an operating system that is close to "real > >> time". Also I need to sometimes interact directly with the computer > >> hardware. FreeDOS fills the bill on both counts and WINDOWS is useless. > >> I appreciate very much what you folks are doing and hope that I can help > >> in some way. > >> I program in FORTH using a FORTH Interpreter/Compiler that I wrote > >> myself in assembler. > > > > This is a way-out-there what-if, but anyhow... How much trouble would it > > be to make FreeDOS explicitly realtime? > > I think what he meant is that because DOS does not put a compulsory > layer between you and the hardware and because DOS does not waste > CPU time in the background, DOS already *is* close to real time and > already lets you interact directly with the hardware. Of course you > have to be aware that when you do file I/O with DOS, it can take a > while - so you would only let DOS do work for you when you are not > in a real-time situation. You can for example measure your diodes, > without accessing DOS, in real time. Then, when the measurement is > done, you can use DOS to save the results in a file. At that moment, > it is no problem that DOS will spend an "unpredictable" amount of > time writing the file before it returns control to the caller, in > this case the diode tester. Note that some unexpected time-wasters > exist: For example USB mice using BIOS PS/2 emulation can have much > more lag in DOS than actual PS/2 mice. Just in case you would want > to measure, say, reaction times by timing the moment of clicking. > > Regards, Eric > > PS: Of course it is much more exact to use directly accessible I/O > bits for time measurement, such as parallel printer port pins, the > joystick port buttons or the serial port status lines. > Thanks Eric. You explained what I am doing better than I did. My tester works pretty much as you described it. Occasionally I will briefly turn off the interrupts when I am doing something especially time critical. FreeDOS is working very well for me.
Regards George > > > > ------------------------------------------------------------------------------ > Simplify data backup and recovery for your virtual environment with vRanger. > Installation's a snap, and flexible recovery options mean your data is safe, > secure and there when you need it. Discover what all the cheering's about. > Get your free trial download today. > http://p.sf.net/sfu/quest-dev2dev2 > _______________________________________________ > Freedos-user mailing list > Freedos-user@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/freedos-user ------------------------------------------------------------------------------ Simplify data backup and recovery for your virtual environment with vRanger. Installation's a snap, and flexible recovery options mean your data is safe, secure and there when you need it. Discover what all the cheering's about. Get your free trial download today. http://p.sf.net/sfu/quest-dev2dev2 _______________________________________________ Freedos-user mailing list Freedos-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freedos-user
