Understanding the Fundamentals of CPU Architecture

Abstract

• Aim: To understand CPU architecture and how a CPU works.
• Method: Building an 8-bit computer from scratch to demonstrate CPU theory.
• Limitations: The project is limited by time and practicality.

Introduction

2.1 Background

• The complexity of computer systems has increased over the years.
• Many people use computers without understanding their underlying technology.

2.2 Goal

• Show the theory behind a simple computer.
• Build an 8-bit computer to demonstrate theoretical concepts in practice.

2.3 Limitations

• Building complexity increases exponentially with features.
• Practicality and troubleshooting are fundamental limitations.

Theory

3.1 Clock Module

• Function: Cycles data/instructions in the computer.
• Determines execution speed (measured in Hz).
• 555 Timer IC is commonly used, adjustable via capacitor and resistor.

3.2 Registers

• Small, fast memory components holding data values.
• Used for storing mathematical numbers and instructions.

3.3 ALU (Arithmetic Logic Unit)

• Mathematical processor performing operations like addition and subtraction.
• Limited by bit size (e.g., 8-bit ALU outputs a max of 256).

3.4 Output

• Holds value intended for the computer’s output.
• Often includes a graphical component for display.

3.5 Counter

• Tells the computer what to start with and indicates its operational stage.

3.6 RAM

• Main storage for programs.
• Static vs. Dynamic RAM: Static uses flip-flops, dynamic uses capacitors.

3.7 Bus

• Communication system for modules (input/output data).
• Essential for computer operation.

Experimental Details

4.1 Designing the Computer

• Focus on showcasing essential computer principles rather than practicality.
• Used 8-bit design for clarity of each computational step.

4.2 Building the Computer

• Constructed and tested in 8 parts: Clock, Registers, ALU, Output, Counter, RAM, Bus.
• Used TTL chips and LEDs for visibility.

4.3 Programming Microcode

• Used EEPROMs for control signals and machine language programming.
• Example instructions: ADD, SUB, LDA, OUT, HLT.

4.4 Running the Code

• Explained via block diagram to show functional flow in the computer.

Results

• Successfully built an 8-bit computer.
• Major challenge: Troubleshooting due to poor understanding and equipment issues.
• Importance of power supply placement and component quality.

Discussion

6.1 Design of the Computer

• Design choices aimed at demonstrating basic computer principles rather than efficiency.
• Modular design facilitated testing but increased complexity.

6.2 Troubleshooting

• Key challenges: Poor cable management, component quality, power supply issues.
• Recommendations: Better equipment and consideration of component specifications.

Conclusion

• Project successfully demonstrated fundamental computer principles.
• Emphasized the need for quality equipment and further study in computer science.

References

1. 555 Timer Tutorial - Electronics Tutorials
2. Jerald A Brown & Albert P Malvino, Digital Computer Electronics
3. Sergei Skorobogatov, "Low Temperature Data Remanence in Static RAM"