🚀 go-pugleaf

On Tue, 22 Aug 1995 00:51:47 GMT, Jay Urbanski (strops@fastlane.net) wrote:
: 
: Nope.  Even Windows 3.0 pre-emptively multi-tasked DOS sessions.  How does
: one have a DOS program call a yield routine anyways?

   Multi-tasking MsDOS apps has absolutely no bearing on the argument, as the
performance gains of multitasking of any sort only appear with processes
that block on I/O.  MsDOS apps never block for any reason.  Hence, the
impact on the system of a single MsDOS app sitting there polling for a
user keystroke can be as or more significant than the heaviest bunch of
number crunching.

   It's because of this that OSes that attempt to multi-task MsDOS applications
always include some sort of heuristic, by which they try to guess whether the
MsDOS app is actually doing any useful work, and then pull the CPU if it
doesn't seem to be.

   In any case, the full suite needed for an OS to take full advantage of the
CPU is preemption, priorities, and blocking I/O.  You need all three, and
you'll never manage that with MsDOS.

-- 
You'd think that after all this time
I would have dreamed up a really clever .sig!