
DS2250(T)
Soft Microcontroller Module
DS2250(T)
021998 1/20
FEATURES
 8–bit 8051 compatible microcontroller adapts to task–
at–hand:
– 8K, 32K, or 64K bytes of nonvolatile RAM for
program and/or data memory storage
– Initial  downloading of software in end  system
via on–chip serial port
– Capable of modifying its own program and/or
data memory in end use
 High–reliability operation:
– Maintains all nonvolatile resources for 10 years
in the absence of V
CC
– Power–fail reset
– Early warning power–fail interrupt
– Watchdog timer
 Software Security Feature:
– Executes encrypted software to prevent  unau-
thorized disclosure
 On–chip, full–duplex serial I/O ports
 Two on–chip timer/event counters
 32 parallel I/O lines
 Compatible with industry standard 8051 instruction
set
 Permanently Powered real time clock
PIN ASSIGNMENT
40–PIN  SIMM
1
20
21
40
DESCRIPTION
The DS2250(T) Soft Microcontroller Module is a fully
8051 compatible 8–bit CMOS microcontroller that offers
“softness” in all aspects of its application.  This is ac-
complished through the comprehensive use of nonvola-
tile technology to preserve all information in the ab-
sence of system V
CC
.  The internal program/data
memory space is implemented using 8K, 32K, or 64K
bytes of nonvolatile CMOS SRAM.  Furthermore, inter-
nal data registers and key configuration registers are
also nonvolatile.  An optional real time clock gives per-
manently powered timekeeping.  The clock keeps time
to a hundredth of a second using an on–board crystal.
All nonvolatile memory and resources are maintained
for over 10 years at room temperature in the absence of
power.