On 10 Jul 00, at 16:02, Matthew Ballard wrote:

> Actually, Windows 95/98/SE/Me use preemptive for all applications
> that support it (most newer ones) but if the app doesn't support
> it, it runs it in cooperative mode.  WinNT/2000 based computers put
> the cooperative tasks in one preemptive thread (or multiple if set
> to do so), and control the amount of resources they get, but one
> cooperative thread in Win95/98/SE/Me can bring the whole system
> down.
>
> Matthew

  The fundamental difference between cooperative and pre-emptive
multi-tasking is that cooperative requires support from each
application, and pre-emptive does not.  There is absolutely no such
thing as an *app* that doesn't support pre-emptive multi-tasking.

  Win 9x, however, includes some core components which are still 16-
bit code and which cannot safely/easily/efficiently be used by more
than one app at a time.  When one app calls any of these, any other
app that tries to call any of them must wait for the first to finish;
effectively, pre-emption is impaired or even disabled at this point.
  And if it hits a bug, the application currently using the core
component may never relinquish it and allow other applications to
proceed.

David G

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