1P1 Vcc40 0.039 2 PPPP 36 P.435 7P1 Pc 9 RST/VPD 10 P3 o/RXD EA/VPP 31 11Pa/个TxD ALE/PROG 30 12 P3. 2/INTo PSEN29 13P33/INT1 P27[28 15P35/T PPPP 26 16P3.6/WR 17 P3.7/RD 18 XTAL2 19 XTALI 20Vs 0 图1-1MCS-51单片机外形图