On 09/26/2013 02:59 PM, Tomas Hajny wrote:
...except when it uses just any RTL function...
ther were lots of "DOS appliances" that could be installed as resident
add-ons. Same e.g. could handle printer queues as well for the local
user as for remote network clients in the background. they could show a
user interface when activated by a hotkey or some other event. So they
did use disk-IO, keyboard, screen and timer hardware.
The technology used as hooking the appropriate hardware interrupts and
DOS API functions and after doing their stuff calling the original (or
previously installed resident appliance).
In fact I remember that at that time I had lots of those running in the
background of my DOS PC.
Obviously the appropriate issues (such as non-reentant DOS calls) have
been handled in a perfect way.
I am positive that this could be done by a multithreading aware DOS RTL
flavor that does user-land reentrand thread scheduling according to the
original (program.internal only) POSIX specs.
(But of course this is not exactly trivial. :-( )
-Michael
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