Subj : Interrupts
To   : Vitus Jensen
From : Lee Aroner
Date : Wed May 23 2001 09:37 am

 RV>> First, OS/2 doesn't use interrupts.  You have to use API calls. 
 RV>> Second, since OS/2 is a multitasking OS, it manages memory much
 RV>> differently than DOS does.

 LA>    Not to niggle the point, but of course OS/2 uses interrupts. Each    
 LA> and every one of those API calls is a wrapper around an interrupt    
 LA> call.

VJ> Well, to be exact: OS/2 uses callgates to jump into kernel code.  Callbacks 

  > are similar to interrupt gates in that they switch 
  > priviledge levels and have a predefined entry point into 
  > the kernel but they additionally copy bytes from lower to 
  > higher level stacks while swichting (byte count defined in 
  > the callgate).  Something what a interrupt gate won't do.
  > It is a common design of OSses to do this switching via a 
  > software interrupt but OS/2 is different.

   Ah, but are not those callgates accessed through an interrupt? 
   It's irrelevant that it is an invalid interrupt, a spade 's a 
   spade after all...


                                       LRA


 -- SPEED 2.01 #2720: "Too much of a good thing is wonderful." <Mae West>

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