Lesson 16 The Basic Digital Logic Gates

Chapter Lesson 16 The Basic Digital Logic Gates

Electronic Circuits for the Evil Genius Second Edition 64 Lessons with Projects
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Electronic Circuits for the Evil Genius Second Edition 64 Lessons with Projects

  • 2.Translate the following 8-bit binary codes tothe decimal equivalent.3.Translate the following decimal numbers tothe binary codes.4.Consider this. If 8 bits count up to 255decimal, what is the maximum that a 9-bitbinary word can count?Lesson 16The Basic Digital Logic GatesYou build prototypes of the five main types oflogic gates in this lesson. Each gate can be builtwith individual transistors that act like normallyopen or normally closed push buttons. All theseswitches do is redirect the output to voltage (V) or ground.The AND gate and NOT AND gate are perfectlyopposite in their outputs. The OR gate and NOTOR gate are also perfectly opposite in their output.In digital electronics, the voltage state is namedin three different ways:■Each term for voltage has an alternate name for ground.■These terms are generally interchangeable.■The terms are usually paired. Terms like Vand ground are used together just like the termhigh is used with low, and 1 with 0.■Digital gives an output of high or low, but weoften have to use a real-world analog input.All gates have at least one input, but all gateshave only one output.Inputs are the analog “sensors.” They comparethe voltage they feel to the voltage of the chip.They sense if the input is to be seen as high or low.Output is the result of the logic function,whether the gate provides a full Vor ground atthe output.■The real world analog input usually neverhappens as a convenient high or low.■So digital gates have been designed to comparethe input against their own power source ofV .■Anything above half of Vis seen as a highinput.■Anything below half of Vis seen as a lowinput.66Section 5 ■Digital LogicBinaryDecimal10101100011001101001001100110001Voltage StatesV+Ground10HighLowDecimalBinary24127191192