| Digital logic gate circuits are manufactured as integrated 
    circuits: all the constituent transistors and resistors built on a single 
    piece of semiconductor material. The engineer, technician, or hobbyist using 
    small numbers of gates will likely find what he or she needs enclosed in a 
    DIP (Dual Inline Package) housing. DIP-enclosed 
    integrated circuits are available with even numbers of pins, located at 
    0.100 inch intervals from each other for standard circuit board layout 
    compatibility. Pin counts of 8, 14, 16, 18, and 24 are common for DIP 
    "chips."
 Part numbers given to these DIP packages specify what type of gates are 
    enclosed, and how many. These part numbers are industry standards, meaning 
    that a "74LS02" manufactured by Motorola will be identical in function to a 
    "74LS02" manufactured by Fairchild or by any other manufacturer. Letter 
    codes prepended to the part number are unique to the manufacturer, and are 
    not industry-standard codes. For instance, a SN74LS02 is a quad 2-input TTL 
    NOR gate manufactured by Motorola, while a DM74LS02 is the exact same 
    circuit manufactured by Fairchild.  Logic circuit part numbers beginning with "74" are commercial-grade TTL. 
    If the part number begins with the number "54", the chip is a military-grade 
    unit: having a greater operating temperature range, and typically more 
    robust in regard to allowable power supply and signal voltage levels. The 
    letters "LS" immediately following the 74/54 prefix indicate "Low-power 
    Schottky" circuitry, using Schottky-barrier diodes and transistors 
    throughout, to decrease power dissipation. Non-Schottky gate circuits 
    consume more power, but are able to operate at higher frequencies due to 
    their faster switching times.  A few of the more common TTL "DIP" circuit packages are shown here for 
    reference:  
      
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