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Memory Organization
Using the Stack Pointer (SP) - a special function register described in section 4.4 - the stack can be
located anywhere in the whole internal data memory address space. The stack depth is limited only
by the internal RAM available (256 byte maximum). However, the user has to take care that the
stack is not overwritten by other data, and vice versa.
External Data Memory
Figure 4-2 and 4-3 contain memory maps which illustrate the internal/external data memory. To
address data memory external to the chip, the "MOVX" instructions in combination with the 16-bit
datapointer or an 8-bit general purpose register are used. Refer to chapter 9 (Instruction Set) or 5
(External Bus Interface) for detailed descriptions of these operations. A maximum of 64 Kbytes of
external data memory can be accessed by instructions using 16-bit address.
*
Figure 4-2
Data Memory / SFR Address Space
Semiconductor Group
21
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