DESCRIPTION
The DS87C520/DS83C520 EPROM/ROM high-speed microcontrollers are fast 8051-compatible microcontrollers. They feature a redesigned processor core without wasted clock and memory cycles. As a result, the devices execute every 8051 instruction between 1.5 and 3 times faster than the original for the same crystal speed. Typical applications will see a speed improvement of 2.5 times using the same code and the same crystal. The DS87C520/DS83C520 offer a maximum crystal speed of 33MHz, resulting in apparent execution speeds of 82.5MHz (approximately 2.5X).

FEATURES
■ 80C52 Compatible
    8051 Pin- and Instruction-Set Compatible
    Four 8-Bit I/O Ports
    Three 16-Bit Timer/Counters
    256 Bytes Scratchpad RAM
■ Large On-Chip Memory
    16kB Program Memory
    1kB Extra On-Chip SRAM for MOVX
■ ROMSIZE Feature
    Selects Internal ROM Size from 0 to 16kB
    Allows Access to Entire External Memory Map
    Dynamically Adjustable by Software
    Useful as Boot Block for External Flash
■ High-Speed Architecture
    4 Clocks/Machine Cycle (8051 = 12)
    Runs DC to 33MHz Clock Rates
    Single-Cycle Instruction in 121ns
    Dual Data Pointer
    Optional Variable Length MOVX to Access Fast/Slow RAM/Peripherals
■ Power Management Mode
    Programmable Clock Source to Save Power
    CPU Runs from (crystal/64) or (crystal/1024)
    Provides Automatic Hardware and Software Exit
■ EMI Reduction Mode Disables ALE
■ Two Full-Duplex Hardware Serial Ports
■ High Integration Controller Includes:
    Power-Fail Reset
    Early-Warning Power-Fail Interrupt
    Programmable Watchdog Timer
■ 13 Interrupt Sources with Six External
■ Available in 40-pin PDIP, 44-Pin PLCC, 44-Pin TQFP, and 40-Pin Windowed CERDIP
■ Factory Mask DS83C520 or EPROM (OTP) DS87C520