D80C51 - CHMOS SINGLE-CHIP 8-BIT MICROCONTROLLER

VCC Supply voltage during normal Idle and Power Down operations VSS Circuit ground Port 0 Port 0 is an 8-bit open drain bidirectional I O port As an output port each pin can sink several LS TTL inputs Port 0 pins that have 1’s written to them float and in that state can be used as high-impedance inp

• of the MCS-51 Family as listed below Pin P3 0 P3 1 P3 2 P3 3 P3 4 P3 5 P3 6 P3 7 Name RXD TXD INT0 INT1 T0 T1 WR RD Alternate Function Serial input line Serial output line External Interrupt 0 External Interrupt 1 Timer 0 external input Timer 1 external input External Data Memory Write strobe External Data Memory Read strobe PIN.