This section describes how memory is organized and used by the BIOS.
Table 1:
FFFFFh
CPU Address Space
-------------------------- F9000h
28KB hard mapped BIOS ROM
-------------------------- F0000h
36KB hard mapped ROM
--------------------------
4 - 16KB Banks E0000h
--------------------------
4 - 16KB Banks D0000h
--------------------------
1 - 64KB Bank C0000h
-------------------------- BC000h
16KB hard mapped ROM
-------------------------- B8000h
CGA Frame Buffer
-------------------------- B4000h
16KB hard mapped ROM
-------------------------- B0000h
MDA Frame Buffer
--------------------------
64KB hard mapped OS Fcns A0000h
-------------------------- Variable*
OS Data
--------------------------
Application Program Area
Variable*
-------------------------- Variable*
DOS
-------------------------- 00600h
DOS Data Area
-------------------------- 00400h
BIOS Data Area
-------------------------- 00000h
Interrupt Vectors
--------------------------
* The size of the Disk Operating System area varies since optional drivers and buffers may occupy variable amounts of RAM.