Registers

• A register is temporary storage
  • Usually associated with the CPU but in other places as well.
• Registers are standard components
  • As you expect, you can buy a register on a chip.
• In digital, the register
  • 
  • Has three inputs
    • D or the data line.
    • en or the enable line,
      • This makes the circuit acitive.
      • Frequently this is a en
    • The clock line
      • When this changes from low to high, the data on the D line is stored in the register.
  • And a single output, the state of the register.
• We can build one of these fro D Flip-flops quite easily.
  • 
• There are NUMEROUS chips that can serve as a register.
• The 74175 is an example
  • 
  • Datasheet
  • This is a common clock 4 single bit d flip-flops.
  • Input
    • clock as above.
    • clear
    • D₁ through D₄
    • Voltage Supply, Ground
  • Output
    • Q₁ through Q₄
    • Q₁ through Q₄
• The digital file