ST90158 - DEVICE ARCHITECTURE
2.4 MEMORY ORGANIZATION
Code and data are accessed within the same line-
ar address space. All of the physically separate
memory areas, including the internal ROM, inter-
nal RAM and external memory are mapped in a
common address space.
The ST9 provides a total addressable memory
space of 4 Mbytes. This address space is ar-
ranged as 64 segments of 64 Kbytes; each seg-
ment is again subdivided into four 16 Kbyte pages.
The mapping of the various memory areas (inter-
nal RAM or ROM, external memory) differs from
device to device. Each 64-Kbyte physical memory
segment is mapped either internally or externally;
if the memory is internal and smaller than 64
Kbytes, the remaining locations in the 64-Kbyte
segment are not used (reserved).
Refer to the Register and Memory Map Chapter
for more details on the memory map.