Achieving 896K required more aggressive "filling" of the upper memory area (UMA). This involved:
If a user lacked a high-resolution video card or specific expansion ROMs, segments B and E could sometimes be populated with RAM.
Breaking the 640K Barrier: The Legacy of 896K.txt and Early PC Memory Expansion
The techniques documented in 896K.txt represent the DIY spirit of early computing. Before the advent of Extended Memory (XMS) and Expanded Memory (EMS) hardware, these hardware-level "hacks" allowed users to extend the life of their 8-bit machines into the early 1990s. It laid the groundwork for the "Upper Memory Block" (UMB) management that would eventually become a standard feature in MS-DOS 5.0 and later. 5. Conclusion