Arithmetic Logic Unit Design for the Simple RISC Computer

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Arithmetic Logic Unit Designfor the Simple RISC
Computer
Group EMJ2
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Arithmetic Logic Unit Design

• Objective
• Introduction
• Design
• Implementation
• Components
• Timing Diagrams
• Conclusion
• References

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Objective

• Learn and experience the benefits of VHDL
• Design the components of an ALU that perform the
  predefined functions specified for the SRC.
• Implement them in VHDL to simulate the operations
  of the ALU.

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Introduction

• ALU (Arithmetic and Logic Unit)
• Responsible for certain arithmetic and logic
  functions. (Exaddition,substaction,and, xor
  etc).
• The Control Unit (CU)
• Keep all elements of the ALU working in a
  harmonic way.
• Different Components can be added as modules to
  help perform certain operations
• Adder, Shifter, Delatch, etc

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Design
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Components

• Adder
• Arithmetic functions are perform in this
  circuits.

1-bit adder
8-bit adder
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Components

• ASI
• Receive the operand of add, subtract and
  increment

1-bit adder
8-bit ASI
8-bit ASI pkg
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Components

• Negator
• Arithmetic functions are perform in this
  circuits.

8-bit negator
8-bit negator pkg
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Components

• Register
• Its is use for the ADC function. The rest of
  the functions done via the 2 buses.

8-bit register
8-bit register pkg
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Components

• Logic
• This circuit performs the logic functions and,
  or and all of the shifting operations.
• It is copied 8 times to work as an 8 bit circuit.

1-bit logic/shifter
1-bit logic/shifter pkg
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Timing Diagram
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Conclusion

• In our design we were able to create an ALU
  capable of completing all of the logic and
  arithmetic functions specified in our simulator.
  
• The design can be used for further continuation
  of a project, in which it can be used as the ALU
  of a microcontroller or CPU.
• Our ALU might not have the fastest performance,
  but it has one of the simplest hardware designs.

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References

• Computer System Design Architecture, second ed,
  Vincent P. Heuring and Harry F. Jordan.
• A 32-Bit ALU Design Example, http//lgjohn.ecen.ce
  at.okstate.edu/5253/lectures/ aludesver.pdf

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Questions