C509-L_97 Datasheet, PDF (30/290 Pages) Siemens Semiconductor Group – 8-Bit CMOS Microcontroller

Memory Organization
C509-L
3.4.2 Normal Mode Configuration
The Normal Mode is the standard 8051 compatible operating mode of the C509-L. In this mode 64K
byte external code memory and 61K byte external SRAM as well as 3K byte internal data memory
(XRAM) are provided. If the XRAM is disabled (default after reset), totally 64K byte external data
memory are available. The Boot ROM is disabled. The external program memory is controlled by
the PSEN/RDF signal. Read and write accesses to the external data memory are controlled by the
RD and WR pins of port 3.
The Normal Mode is entered by keeping the pin PRGEN at a logic low during the rising edge of the
external RESET or HWPD signal. The locations of the code- and data-memory in Normal Mode are
shown in figure 3-4.
Figure 3-3
Locations of Code- and Data Memory in Normal Mode
Semiconductor Group
3-5
1997-10-01