GENERAL DESCRIPTION
The W78E51B is an 8-bit microcontroller which can accommodate a wider frequency range with low power consumption. The instruction set for the W78E51B is fully compatible with the standard 8051. The W78E51B contains an 4K bytes MTP ROM (Multiple-Time Programmable ROM); a 128 bytes RAM; four 8-bit bi-directional and bit-addressable I/O ports; an additional 4-bit I/O port P4; two 16-bit timer/counters; a hardware watchdog timer and a serial port. These peripherals are supported by seven sources two-level interrupt capability. To facilitate programming and verification, the MTPROM inside the W78E51B allows the program memory to be programmed and read electronically. Once the code is confirmed, the user can protect the code for security.

FEATURES
• Fully static design 8-bit CMOS microcontroller
• Wide supply voltage of 4.5V to 5.5V
• 128 bytes of on-chip scratchpad RAM
• 4 KB electrically erasable/programmable MTP-ROM
• 64 KB program memory address space
• 64 KB data memory address space
• Four 8-bit bi-directional ports
• One extra 4-bit bit-addressable I/O port, additional INT2 / INT3 (available on 44-pin PLCC/QFP package)
• Two 16-bit timer/counters
• One full duplex serial port(UART)
• Watchdog Timer
• seven sources, two-level interrupt capability
• EMI reduction mode
• Built-in power management
• Code protection mechanism
• Packages:
    - DIP 40: W78E51B-24/40
    - PLCC 44: W78E51BP-24/40
    - PQFP 44: W78E51BF-24/40