6,144
6,144
Posted Aug 9, 2014 17:10 UTC (Sat) by dlang (guest, #313)In reply to: 6,144 by jzbiciak
Parent article: 3.17 merge window part 1
> it was probably due to the memory map they established with the original IBM PC. The MDA and CGA adaptors started at B:0000 and B:8000, which prevents you from going to 768K of contiguous memory without moving them and breaking compatibility with the original 5150
exactly, it wasn't until the memory got cheap enough in larger sizes that manufacturers started installing 1M of RAM on the boards even though the system could only use 640K (because it was cheaper for them to do so then to deal with two sizes of chips) that high memory was born.
and when the XT was shipped (at a price of ~$5K IIRC with two floppies and 16K of RAM, imagining that 640K would be limiting was hard.
I don't miss those days either.