Date: Mon, 29 Mar 93 20:44:00 MST
From: bob AT plk DOT af DOT mil (Bob Conley)
To: djgpp AT sun DOT soe DOT clarkson DOT edu
Subject: DOS int 2f (Multiplex service interrupt)


How does a C program using the djgpp port of GNU C to MSDOS perform the
software interrupt "int 2f" (the DOS multiplex service interrupt)?  I have
tried the assembler instruction as well as a call to the gcc function
int86 (0x2f,&r,&s), both with the same result: both fail, producing an
exception 47 (2f) error.  In go32 this aborts the program to the DOS
shell, and in debug32 an exception error message indicates that the interrupt
was not processed.  My program requires this interrupt to communicate with
a device handler for a peripheral card, and I have been unable to discover
how to write a gcc program which causes the desired operation.

Thanks to anyone who can explain how this can be made to work in gcc.

   Bob Conley
   (505) 281-3354 (home)
   (505) 846-4844 (work)
   conley AT plk DOT af DOT mil