XPost: rec.crafts.metalworking, alt.comp.os.windows-xp   
   From: djb@djbillington.freeserve.co.uk   
      
   Lloyd E. Sponenburgh wrote:   
   >>> My interest is a laptop-based data acquisition system which requires   
   >>> low-level I/O hardware drivers I can only run from DOS, since Windows   
   >>> interferes by polling them and has too much overhead for accurate   
   >>> timing.   
   >>>   
   >   
   > I have a Windows-based data acquisition system that will do 14.1KS/s, at   
   > ten bits per sample.  It's dead-to-nuts accurate.   
   >   
   > The simple reality is that even older DOS-based systems had some   
   > interrupt-service timing jitter visible even in tight hardware polling   
   > loops.   
   >   
   > The secret to doing accurate DAQ, even with dedicated hardware doing the   
   > computing, is to do some local buffering of the samples in the DAQ   
   > hardware, so that retrieving them doesn't have to be in "real time", so   
   > long as the computer can retrieve them faster than the sampling rate.   
   >   
   > LLoyd   
   >   
   OK a different kettle of fish, we were polling a load measuring   
   instrument on its serial port at 9600 baud typically but the normal   
   scheduler rate effected the timing too much so had to bump up the   
   scheduler rate to get finer granularity. Windows allows you to do that   
   but they don't make it easy to find the information. We only up'ed it   
   during acquisition and put it back to normal when we stopped acquisition.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)