High performance CMOS flash version of the 80C51 CMOS, single-chip, 8-bit microcontroller with a 128-KB flash memory block. The flash memory can be programmed in parallelor serial mode using the ISP capability or with software. The programming voltage is internally generated from the standard VCC pin.

This device retains all features of the Atmel 80C52 and adds a programmable counter array, 8192 bytes of XRAM, hardware watchdog timer, SPI and keyboard, two serial channels that facilitate multiprocessor communication (EUART), speed improvement mechanism (X2 mode), and a mode that allows the stack to be extended in the lower 256 bytes of XRAM.

A fully static design reduces system power consumption by bringing the clock frequency down to any value without data loss. Two software-selectable modes of reduced activity and an 8-bit clock prescaler further reduce power consumption.

These features add power for applications that need pulse width modulation, high speed I/O, and counting capabilities such as alarms, motor control, corded phones, and smart card readers.