Hi Sylvain,
SL>  > In other words... chain the interupt...
SL> final approach before closing the subject. Take a look in ralf brown's
SL> int on
SL> this and let me know what you think.
I've seen those before... I have a pretty complete list of my own...
In almost ALL cases you want to chain the interupt. Even if the interupt
routien your chaining is an IRET. There are (or can be) instances where
some "other" program or system may do this.
You should see some of the tricks programers use with chaining interupts
so that it makes it difficult to hack their software protection.
The biggest things to keep in mind with programming TSR's it that you
HAVE to chain into an interupt that is in constant use by the system.
In most cases you will chain the "timer tick" interupt as it is one
that will almost allways happen despite whatever is running at the time.
If your gonna use "DOS" specific funtions within your TSR you will need
to keep track if the "IN_DOS" flag. The reasons for this is that DOS
ain't too re-entrant. (mostly from lack of stack space)
The first TSR I wrote replaced the "print scrn" key with a way to save
screens to seperate text files. It was great for grabbing the contents
of the "online manuals" that are soooo popular with some programs.
Glen.
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