Mail Archives: djgpp/2003/07/13/10:00:58
> In fact, I really did the experiment again and again. I changed the
> interrupt source to a function generator, which can provide more
> stable square wave. And I tried PMODE, too. But similiar result was
> got.
PMODE uses a completely different code base - so if you are seeing
a similar result I suspect it's something in the hardware or BIOS
configuration.
> I am not clear with NMI or bus reset. In what cases NMI or bus reset
> will be triggered? In my mind, only power off can trigger NMI. But how
> about bus reset?
NMI can be generated by the hardware for many reasons - for everything
from memory errors to "advanced" functions like power management and
other "green" PC functions.
Depending on your system, you might have ECC memory - which the
chip set (not CPU) manages (should be very infrequent) errors, which
would would cause a delay while it is being processed. There will
be similar low level error handling when communicating with other
peripherals.
> Actually, I find that some dos programs have strange behaviors in new
> CPUs, such as P3 or P4, but work well in some old Pentium systems.
> Maybe it is due to the bad design of bios?
Some of the problem is bad BIOS, but some is just new features
which make them more Windows specific and less general purpose.
I've also seen the average quality of some of the legacy parts
(parallel, serial, floppy) drop over the last few years.
Sometimes a machine from a different manufacturer will work better.
> But programms running in
> pure protected mode will not call any BIOS funcitons, right?
If you take complete control of the interrupt table and replace ALL
of the vectors, you can be sure you will stay in protected mode.
> Is it possible to get an interrupt response time within small range in
> protected mode? so tough...
Yes, but you many end up having to use a different computer.
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