Internal Data Memory - Siemens C500 User Manual

FFFF H
2000
H
1FFF H
0000 H
The location of the ROM boundary depends on the specific C500 devices.
Figure 1-1
Program Memory Configuration (Example of the C501)
1.2.2 Data Memory
The data memory area of the C500 family microcontrollers consists of internal and external data
memory portions. The internal data memory area is addressed using 8-bit addresses. The external
data memory and the internal XRAM data memory are addressed by 8-bit or16-bit addresses.
The content of the internal data memory (also XRAM) is not affected by a reset operation. After
power-up the content is undefined, while it remains unchanged during and after a reset as long as
the power supply is not turned off. The XRAM content is also maintained when the C500
microcontrollers are in power saving modes.
1.2.2.1

Internal Data Memory

The internal data memory address space is divided into three basic, physically separate and distinct
blocks: the lower 128 byte of internal data RAM, the upper 128 byte of internal data RAM, and the
128 byte special function register (SFR) area. The lower internal data RAM and the SFR area
further include 128 bit locations each. These bits can be handled by specific bit manipulation
instructions.
Semiconductor Group
EA = 1
External
Program
Memory
ROM
Boundary
Internal
Program
Memory
EA = 0
FFFF
H
External
Program
Memory
0000
H
1-3
Fundamental Structure
C500 Family
MCD02766
1998-04-01