High-end EGA and VGA cards utilized the A segment for their frame buffers, making the 704K/896K mod incompatible with modern (for the time) graphics.
Because the IBM BIOS did not officially support RAM in these segments, some software that bypassed DOS to check memory limits would fail to "see" the extra space. 4. Historical Significance
The original IBM PC architecture utilized the Intel 8088 processor, which had a 20-bit address bus capable of addressing 1 MB ( 2202 to the 20th power
The 896K.txt methodology relies on the fact that while the memory segments A000hcap A 000 h FFFFhcap F cap F cap F cap F h
While 896K provided a massive boost for memory-resident programs (TSRs) and large spreadsheets, it introduced several risks: