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c++.dos.32-bits - Preemptive multitasker MTask version 2.01

I have just finished version 2.01. I think timer interrupts are handled 
properly now, including the possibility to have a timer callback (just 
one callback, I preferred to keep it simple). Changes from 2.00 are:

* InitMTask() defines the timer interrupt period, from 1 to 55 msecs.
* SetHandler() panics if you try to trap IRQ0. You were not supposed to 
do it anyway, but it is enforced now.
* There is a new function, GetTime(), that returns the number of 
milliseconds elapsed since InitMTask().
* There is a new function DelayUntil(), intended for periodic tasks, 
that puts a task to sleep until some deadline time in the future.
* There is a new function SetTimerCallback() for installing a callback 
that will be called from the timer interrupt.

I also added a new test program (ptime.exe) for exercising the new 
features. Internally little has changed in the kernel, except 
programming the timer frequency and the fact that times are now measured 
in millisecs instead of ticks.
Sep 26 2003