AT89S52-24PU
8 KByte program memory in flash technology.
256 x 8 bit RAM data memory, no EEPROM data memory. With isp function (successor to the AT89C52).
32 I/O lines with 10 mA sink/pin (total max. 71 mA).
Three 16-bit timers/counters, eight interrupt sources.
Serial UART interface.
External address/data bus.
24 MHz clock
DIP40
AT89S52.pdf
256 x 8 bit RAM data memory, no EEPROM data memory. With isp function (successor to the AT89C52).
32 I/O lines with 10 mA sink/pin (total max. 71 mA).
Three 16-bit timers/counters, eight interrupt sources.
Serial UART interface.
External address/data bus.
24 MHz clock
DIP40
AT89S52.pdf 
