SAB80C517-M16 SIEMENS [Siemens Semiconductor Group], SAB80C517-M16 Datasheet - Page 17

• Manufacturer Part Number: SAB80C517-M16
• Description: 8-Bit CMOS Single-Chip Microcontroller
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

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, pay attention to the fact 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 a 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 a 16-bit address.
The datapointer structure in the SAB 80C517 deserves special attention, since it consists of eight
16-bit registers which can be alternatively selected as datapointers. See section 4.4 and chapter 5
for further details.
Figure 4-2
Data Memory / SFR Address Spaces
Semiconductor Group
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