First post, by tigrou
Let's say I have a physical DOS PC with 1 MB of RAM installed and CPU runs in 16-bit real mode.
The first 640KB (conventional memory) can be used by programs (minus DOS internals stuff and TSRs).
AFAIK this part is directly mapped to the 0-640 KB region of physical RAM.
The 640KB-1MB region (UMA) is mapped to VGA, peripheral cards, ROMS, BIOS, ....
What about the 640KB-1MB region in the physical RAM stick ? Is it lost (not usable ? )
Or can it be used ? (eg : through EMS/XMS).
I have notified that DOSBox automatically disable EMS if memsize=1. I don't know if it's a limitation of DOSBox or if it also happen on a physical machine.