C504 Datasheet, PDF (13/49 Pages) Siemens Semiconductor Group – 8-Bit CMOS Microcontroller

Memory Organization
The C504 CPU manipulates operands in the following four address spaces:
– up to 64 Kbyte of external program memory
– up to 64 Kbyte of external data memory
– 256 bytes of internal data memory
– 256 bytes of internal XRAM data memory
– a 128 byte special function register area
Figure 4 illustrates the memory address spaces of the C504.
C504
Figure 4
C504 Memory Map
The XRAM in the C504 is a memory area that is logically located at the upper end of the external
memory space, but is integrated on the chip. Because the XRAM is used in the same way as
external data memory the same instruction types (MOVX instructions) must be used for accessing
the XRAM. The XRAM can be enabled and disabled by the XMAP bit in the SYSCON register.
ROM Protection
The C504-2R ROM version allows to protect the content of the internal ROM against read out by
non authorized people. The type of ROM protection (protected or unprotected) is fixed with the
ROM mask. Therefore, the customer of a C504-2R ROM version has to define whether ROM
protection has to be selected or not.
Semiconductor Group
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