
DS89C430/DS89C440/DS89C450 Ultra-High-Speed Flash Microcontrollers 
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Figure 5. Functional Diagram 
CONTROL 
AND 
SEQUENCER
INTERNAL 
REGISTERS
DECODER 
IR
INTERRUPT
CPU
SERIAL I/O 
TIMER/
COUNTERS
1kB x 8 
RAM
16kB/32kB
64kB x 8 
FLASH
I/O PORTS
SFRs 
DPTR
DPTR1 
SP
PC 
AR INC
AR 
WATCHDOG TIMER 
AND 
POWER MANAGER 
CLOCK 
AND 
 RESET 
MEMORY 
CONTROL 
ROM 
LOADER
X
X
R
P
S
E
A
P
P0 P1
P2
P3
ADDRESS BUS
INTERNAL CONTROL BUS
DETAILED DESCRIPTION 
The DS89C430, DS89C440, and DS89C450 are pin compatible with all three packages of the standard 8051 and 
include standard resources such as three timer/counters, serial port, and four 8-bit I/O ports. The three part 
numbers vary only by the amount of internal flash memory (DS89C430 = 16kB, DS89C440 = 32kB, DS89C450 = 
64kB), which can be in-system/in-application programmed from a serial port using ROM-resident or user-defined 
loader software. For volume deployments, the flash can also be loaded externally using standard commercially 
available parallel programmers. 
Besides greater speed, the DS89C430/DS89C440/DS89C450 include 1kB of data RAM, a second full hardware 
serial port, seven additional interrupts, two extra levels of interrupt priority, programmable watchdog timer, 
brownout monitor, and power-fail reset. Dual data pointers (DPTRs) are included to speed up block data-memory 
moves with further enhancements coming from selectable automatic increment/decrement and toggle select 
operation. The speed of MOVX data memory access can be adjusted by adding stretch values up to 10 machine 
cycles for flexibility in selecting external memory and peripherals. 
A power management mode consumes significantly lower power by slowing the CPU execution rate from one clock 
period per cycle to 1024 clock periods per cycle. A selectable switchback feature can automatically cancel this 
mode to enable normal speed responses to interrupts. 
For EMI-sensitive applications, the microcontroller can disable the ALE signal when the processor is not accessing 
external memory. 
Dallas Semiconductor 
DS89C430/DS89C440/ 
DS89C450