How To XMP!
I was just about to post the same question my has 9 MB of RAM reserved for "system use" according to the BIOS and i cant help but wonder what for.
From the program's point of view, here's what happens: 1. The program is written in such a way that part of it is a Strategy Routine for a given interrupt. The program is run by the user.
While running, the program determines the address in memory of its Strategy Routine. The program stores this address in the interrupt vector table, at the address corresponding to key-stroke interrupts.
The Strategy Routine examines the key-stroke and decides whether or not to pop-up. We'd hook interrupt 0x16, which is executed every time a complete key-stroke is available in the BIOS's key-board buffer. Since DOS was not designed to cleanly support such manoeuvres, such programming is fraught with difficulties It is memory beyond the 1 Mb boundary.