DOS Task's Memory Usage
1st MB Is DOS Memory
Each DOS task believes that it resides within and interacts with other programs residing within the first megabyte of memory space (the linear address range from 00000000h through 000FFFFFh; see Figure 15-2 on page 335).
Figure 15-2. DOS Task's Perception of the 1st MB of Memory Space
Paging Provides Each DOS Task with Its Own Copy of the 1st MB
If multiple DOS tasks are being run under a multitasking OS, each of them, when active, performs memory reads and writes within the first megabyte of linear memory space. The currently executing DOS task can easily alter the contents of memory locations that ...