AT89C4051-24PC .

Description: IC MCU 8BIT 4KB FLASH 20DIP, Packaging: Tube, Package / Case: 20-DIP (0.300", 7.62mm), Mounting Type: Through Hole, Speed: 24MHz, Program Memory Size: 4KB (4K x 8), RAM Size: 128 x 8, Operating Temperature: 0°C ~ 70°C (TA), Oscillator Type: Internal, Program Memory Type: FLASH, Core Processor: 8051, Core Size: 8-Bit, Voltage - Supply (Vcc/Vdd): 4V ~ 6V, Connectivity: UART/USART, Peripherals: Brown-out Detect/Reset, LED, POR, Supplier Device Package: 20-PDIP, Part Status: Obsolete, Number of I/O: 15, DigiKey Programmable: Not Verified.