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JCM inVentures Inc.

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Identify Symbols for basic logic gates

This page will describe the symbols used for the fundamental logic gates used in computer systems and robotics, and how those gates are connected in standard DIP integrated circuit packages. 

After reviewing this page, you can proceed onto the next section which discusses the function of these gates.

Resources:

For this section you should have the following resources:

bulletVulcan Logic Trainer
bullet22 gauge wire
bulletVirtual Vulcan Logic Simulator
bulletMulti-media logic Simulator

Gate Symbols

Logic gates used in digital electronics take several basic forms.  The table below shows the names of each type of fundamental gate, how the gate is connected in the package, and the electronic symbol we use when we draw circuit diagrams for those gates.

You notice that there are actually 4 gates in each package ( six in the inverter! ).

 

Name  Packaging Symbol
AND Gate
NAND Gate
OR Gate
NOR Gate
XOR Gate
Inverter

The numbers on the "Package" are assigned in a counter-clockwise fashion around the chip and help us locate the pin on that package.  Pin 14 is to be connected to a 5 volt supply and pin 7 to ground in order to provide power to the chip.

DIP Package

Standard Dual In-line Package

The image shown above is a typical logic chip as used in digital electronics in a DIP (Dual In-line) package. Pin 1 is marked with a small dimple in the plastic, and the top of the chip is marked with a semi-circular impression and a white band.  Some manufacturers only give us one or two of these identifying marks, but this has all three!

The package also has numbers on it which identify the manufacturer, when it was built, and the type of chip it is...  a DM7407 in this case.