User`s guide

To expand memory capacity beyond the 64K address space of an 8-bit micropro-
cessor, CP/M 3 supports bank-switched memory in a special version called the banked
system. In the banked version, the operating system is divided into two modules: the
resident portion and the banked portion. The resident portion resides in common
memory; the banked portion resides just below the top of banked memory in Bank 0.
Figure 1-2 shows memory organization under the banked system.
Figure 1-2. Banked System Memory Organization
In Figure 1-2, Bank 0 is switched in or in context. The top region of memory, the
common region, is always in context; that is, it can always be referenced, no matter
what bank is switched in. Figure 1-3 shows memory organization when Bank 1 is in
context.
1-3
1.1 Baked/Nonbanked Organization CP/M 3 Programmer's Guide