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Using Multiple CPU Cores in DOS? (Miscellaneous)

posted by tom(R) Homepage, Germany, 20.09.2011, 12:02

> > wrong. A20 will be enabled almost always, and only a few microseconds
> after
> > program has started; you won't notice a difference
>
> IRQ's don't stop just because a "real" program starts running. Unless I'm
> missing something, it doesn't make sense to have IRQ's execute quickly at a
> command prompt and slowly while a program is running. At least that seems
> to me to be what you're suggesting.

seems my english writing skills need refinement. retrying:


A20 will be enabled by each INT 21, (usually DOS lives in memory above 1M), and left enabled.
A20 is disabled when when a program is started.
as most programs call int 21 sooner or later, A20 is reenabled again by int 21, and left enabled.

therefore it's fast, almost all time.

 

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