22 Apr
2007
22 Apr
'07
3:30 a.m.
On Sat, 21 Apr 2007, Geoff Reed wrote:
The 640K barrier was due to the location of the memory
map for CGA graphics
IIRC. If you were running monochrome you could squeeze a little more ram
out of the system IIRC.
CGA was at segment B800.
MDA was at segment B000
640K was at segment A000
A000 - B000 was "reserved for future expansion (EGA, VGA, etc.)
384K seems like a lot of space to set aside. But, at the time, 640K was
10 times what was otherwise available (64K), and surely nobody would need
more than THAT!