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RE: executor & windows95



>>>>> "Glenn" == Glenn R Keyser <GGS@ns.net> writes:

    Glenn> Looking at these results gives me a question.  Why isn't
    Glenn> -oldtimer part = of the default settings when it makes the
    Glenn> emulation run much faster?? = What are the pluses and minus
    Glenn> of using -oldtimer?

The main timer on a real Mac runs at 60 Hz (although there are other
timers).  The main timer on a PC runs at 18.2 Hz.  It is possible to
reprogram the PC's timer to run at 60 Hz, but that's caused problems
in the past, and may not be allowed on advanced OS's like WinNT.

Executor/DOS normally uses the PC's 1024 Hz timer, and uses that to
emulate a 60 Hz Mac timer.  That works well, since the 1024 Hz timer
is so much faster.  However, that technique generates 1024 timer
interrupts a second which can cause problems for some slower systems.

"-oldtimer" tells Executor to only use the 18.2 Hz timer.  That
generates fewer interrupts (so it's faster) but it can't emulate a Mac
60 Hz timer very well.  Often this doesn't matter, but some games do:

<wait for 60 Hz timer to "tick">
draw something
<wait for 60 Hz timer to "tick">
draw something
<wait for 60 Hz timer to "tick">
draw something

So with only an 18.2 Hz timer, these games run about 1/3 normal speed.
I think Solarian may be in this category but I'm not sure.  Some
Windows setups (incl. all WinNT setups) don't give us a reliable 1024
Hz timer, so Executor is forced to only use the old 18.2 Hz timer.

You can tell which timer your setup is using by running the Globe demo
and choosing the "sync to VBL" menu option.  If you see 60 fps, you're
running with the 1024 Hz timer.  If you see 18 fps, you've got the old
timer.

I hope that clears things up.

-Mat


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