Datasheet

DS2250(T)
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INSTRUCTION SET
The DS2250(T) executes an instruction set which is object code-compatible with the industry standard
8051 microcontroller. As a result, software development packages which have been written for the 8051
are compatible with the DS2250(T), including cross-assemblers, high-level language compilers, and
debugging tools. Note that the DS2250(T) is functionally identical to the DS5000(T) except for package
and the 64k memory option.
A complete description for the DS2250(T) instruction set is available in the Secure Microcontroller
User’s Guide.
MEMORY ORGANIZATION
Figure 2 illustrates the address spaces which are accessed by the DS2250(T). As illustrated in the figure,
separate address spaces exist for program and data memory. Since the basic addressing capability of the
machine is 16 bits, a maximum of 64 kbytes of program memory and 64 kbytes of data memory can be
accessed by the DS2250(T) CPU. The 8- or 32-kbyte RAM area inside of the DS2250(T) can be used to
contain both program and data memory. A second 32k RAM is available for data only.
The Real Time Clock (RTC) in the DS2250(T) is reached in the memory map by setting a SFR bit. The
MCON.2 bit (ECE2) is used to select an alternate data memory map. While ECE2=1, all MOVXs will be
routed to this alternate memory map. The real time clock is a serial device that resides in this area. A full
description of the RTC access and example software is given in the Secure Microcontroller User’s Guide.
DS2250(T) MEMORY MAP Figure 2
DATA MEMORY (MOVX)