I'm developing software for the IBM PC with an 8086 processor. I want my program to use all available memory.
I know that I can use DOS int 21h function AH=48h to allocate all available conventional memory between 0 and 640K. But how do I allocate and use all RAM between 640K and 1024K?
Maybe there is not much RAM there, only video memory, which can be very small (less than 68K in total). Nevertheless, I want to use everything available.
As a historical curiosity, were there any IBM PC 8086 systems with more than 640K of RAM in use?