DS5000(T)

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INSTRUCTION SET

The DS5000(T) executes an instruction set which is object code-compatible with the industry standard

8051 microcontroller. As a result, software development packages that have been written for the 8051,

including cross-assemblers, high-level language compilers, and debugging tools, are compatible with the

DS5000(T).

A complete description for the DS5000(T) instruction set is available in Secure Microcontroller User’s

Guide.

MEMORY ORGANIZATION

Figure 2 illustrates the address spaces, which are accessed by the DS5000(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 DS5000(T) CPU. The 8- or 32-kbyte RAM area inside of the DS5000(T) can be used to

contain both program and data memory.

The real-time clock (RTC) in the DS5000T 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 RTC 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.

If the ECE2 bit is set on a DS5000 without a timekeeper, the MOVXs will simply go to a nonexistent

memory. Software execution would not be affected otherwise.