CMOS SINGLE-CHIP 8-BIT MICROCONTROLLER WITH 4K BYTES OF EPROM MEMORY

The 87C51 is the EPROM version of the 80C51. Microcontroller fabricated with highdensity CMOS technology. It contains 4K bytes of on chip Program memory that can be electrically programmed The 80C51 contains a 4k x 8 ROM , a 128 x 8 RAM , 32 I/O lines, two 16-bit counter/timers, a five-source, two-priority level nested interrupt structure, a serial I/O port for either multi-processor communications, I/O expansion or full duplex UART, and on-chip oscillator and clock circuits.
The device has two software selectable modes of power reduction  idle mode and power-down mode. The idle mode freezes the CPU while allowing the RAM, timers, serial port, and interrupt system to continue functioning. The power-down mode saves the RAM contents but freezes the oscillator, causing all other chip functions to be inoperative.

FEATURES
8031/8051 compatible (MCS-51 family)
   ― 4K EPROM
   ― 128 x 8 RAM
   ― Two 16-bit counter/timers
   ― Full duplex serial channel
   ― Boolean processor
   ― Memory addressing capability
      ― 64k ROM and 64k RAM
      ― Power control modes:
   ― Idle mode
   ― Power-down mode
   ― CMOS and TTL compatible
   ― Two speed ranges at VCC=5V
   ― 12 MHz
   ― 16 MHz