| Symbol | Parameter | Min | Typical (Note 4) | Max | Units | Test Conditions |
| VIL | Input Low Voltage | - 0.5 | | 0.2 Vcc - 0.1 | v | |
| VIL1 | Input Low Voltage EA | 0 | | 0.2 Vcc - 0.3 | v | |
| VIH | Input High Voltage (Except XTALl, RST) | 0.2 Vcc+0.9 | | Vcc+0.5 | V | |
| VIH1 | Input High Voltage (XTALl, RST) | 0.7 Vcc | | Vcc+0.5 | V | |
| VOL | Output Low Voltage (Note 5) (Ports l, 2 and 3) | | | 0.3 0.45 1.0 | V | IOL = 100 y,A IOL = 1.6 mA (Note l) IOL = 3.5 mA |
| VOL1 | Output Low Voltage (Note 5) (Port 0, ALE/PROG, PSEN) | | | 0.3 0.45 1.0 | V | IOL = 200 y,A IOL = 3.2 mA (Note l) IOL = 7.0 mA |
| VOH | Output High Voltage (Ports l, 2 and 3 ALE/PROG and PSEN) | vcc - 0.3 vcc - 0.7 Vcc - 1.5 | | | V | IOH = -10liA IOH = -30 y,A (Note 2) IOH = -60lLA |
| VOH1 | Output High Voltage (Port o in External Bus Mode) 83C51FA/80C51FA (Express) | Vcc - 0.3 Vcc - 0.7 Vcc - 1.5 | | | V | IOH = -200 FLA IOH = -3.2 mA (Note 2) IOH = -7.0 mA IOH = -6.0 mA |
| l¨_ | Logical O Input Current (Ports l, 2 and 3) | | | - 50 | uA | VIN=0.45V |
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