Date: Sun, 6 Apr 1997 14:58:37 -0600 (MDT) From: Ramesh Nallur To: djgpp AT delorie DOT com Subject: Interrupts (Hardware) Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Hai! I know that there have been too many questions and answers about interrupts but my question is slightly different, I want to exactly know how interrupts are handled by the DPMI server?. Let me first tell what I know, When a program runs in PM the IDT is replaced and the interrupts are caught here. But I think the hardware interrupts are not caught here. As I understand from the notes they are caught in the real mode. But how is this possible when the IDT has been replaced. And if they are caught in the RM, should not be there a switching of modes for every hardware interrupt? There have been lot of notes about reflecting the RM interrupt to PM. What exactly does reflecting mean? Does it mean that actually the table at 0000:0000 is used when a hardware interrupt occurs in PM? Has it got to do anything with setting up the PIC? Why cant I just overwrite an IDT entry in PM and expect interrupts to be caught? I looked at the code for the __dpmi_set_protected_mode_int_vec and I saw that there is some restoration or reflection of the RM handlers (0000:0000). Why is this being done?. I am really confused whats happening here.. Could anybody help me please, Thanks in advance. Ramesh Nallur (Nalluri) RES. PH: 505 838 4900. Address: P.O. BOX. 2145, NM TECH, Res. Address: 300, MT. Carmel Ave. New Mexico Tech, Socorro, New Mexico. Socorro, New Mexico. USA 87801. USA 87801.