ATMEL AT89C51RC2 handbook

The 80E52 is the successor to the Intel 8051 microcontroller, and is an 8-bit single-chip microcomputer with an 8051 compatible instruction set. The 80E52 has all the features of the 80C52, and also adds some enhanced features, such as 3 16-bit timers/counters, 1024 bytes of internal expanded RAM, and asynchronous port reset function.