DS5000(T)

021998 4/19

PIN NUMBER

DESCRIPTION

32–39

P0.7–P0.0. General purpose I/O Port 0. This port is open–drain and can not drive a

logic 1. It requires external pull–ups. Port 0 is also the multiplexed Expanded Address/Data

bus. When used in this mode, it does not require pull–ups.

40

INSTRUCTION SET

The DS5000(T) executes an instruction set which is ob-

ject 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 DS5000(T), including cross–as-

semblers, high–level language compilers, and debug-

ging tools.

A complete description for the DS5000(T) instruction

set is available in the User’s Guide section of the Secure

Microcontroller Data Book.

MEMORY ORGANIZATION

Figure 2 illustrates the address spaces which are ac-

cessed 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 64K bytes of program

memory and 64K bytes of data memory can be ac-

cessed by the DS5000(T) CPU.

The 8K or 32K byte

RAM area inside of the DS5000(T) can be used to con-

tain 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 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 User’s

Guide section of the Secure Microcontroller Data Book.

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.