Memory stuff ...
I'll try to fill in some background.
The DOS MEM reports how much DOS memory is free, while the System Monitor reports on ALL your free memory, not just what's available and usable by DOS.
We have the famous 640k limit. 8088 processors had 20 address pins. 2^20 is one meg which is all this processor could access directly. Of this address space, some was reserved for DOS and some for video, leaving 640k for user programs. DOS doesn't need all the address space reserved for it. Loading 'High' puts some code into this unused space; thus, this code doesn't consume precious 'lower 640' memory.
This stuff is a concern for people trying to squeeze DOS programs into their system. Few need worry about this stuff today.
Today, Windows manages program space and exploits the 32 address lines of 386 processors. These advances allow us to load programs until our system runs out of memory. We stuff our boxes with chips so we don't run out of memory. Software creators notice the larger memory of most machines and write programs to exploit these available resources. We upgrade. They upgrade. The cage spins and the hamster tires.
Hope this helps, PW.
P.S. I'm going by memory (sorry about the pun) now. Early video cards reserved address B000H, with B000H used by monochrome cards and B800H used for colour (wasting 800H). As the card displayed more complex data, more memory was used. Displaying motion required one page be displayed as the next was updated, and switching pages. Although clumsy by today's standerds, programmers a decade or so ago wrestled with this stuff daily.
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