Hi Chris::
  Christopher Butler,
  In a message on 29 July, wrote :
CB> How do I hook and/or chain an interrupt in C++? (using Turbo C++)
An excerpt of an ISR:
 void interrupt myHook()
 {
  (*oldHook)(); /* Give the old ISR a chance */
  /* Put your code here */
 }
 void interrupt* oldHook;
 main()
 {
  oldHook=getvect(0x8); // 0x8 = timer interrupt
     // You may try others ..
  setvect(0x8,myHook);
  keep(MEM,0); // MEM = amount of RAM your executable
    // will occupy. Try big values for MEM
   // and go on reducing it till your program crashes
   // In other words fix MEM by trial and error ..
   // There *is* a better method of getting a value
   // for MEM but you can figure it out yourself
   // once you understand the various segments in the
   // program - DS, CS, SS and the heap.
 }
Most DOS functions (int 21h) are non-reentrant so don't call them from
inside myHook().
The above example *chains* interrupt 0x8.
Let me know how you do with ISRs ( I am hoping you wanted that info for
writing your own ISRs ).
Bye
Rajesh
  
...
 * ATP/Linux 1.50 *  Never squat with your spurs on.
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