Basic Computer Simulation

Project Description

Implement a simulation of a basic computer memory system, arithmetic/logic unit (ALU), and a set of registers. These components will be interconnected through a common bus controlled by three select lines (S2, S1, S0).

1. Memory (RAM)

   • Size: 128 addresses (words).
   • Each word is 16 bits.
   • Users can read from and write to memory.
   • The Address Register (AR) output connects to the memory's address lines.
   • Memory's input and output lines are connected to the common bus.

2. Registers

   • Available registers: DR, TR, AR, AC (Accumulator Register), PC, IR.
   • Each register has a load enable flag to control data updates from the bus.
   • Registers do not have increment (INC) or clear (CLR) capabilities.

3. ALU (Arithmetic/Logic Unit)

   • Two inputs: A (from DR) and B (from AC).
   • Control lines (C2, C1, C0) determine the ALU operations:
     • (001) Transfer input A
     • (010) Increment A
     • (011) Multiply A * B
     • (100) Subtract A - B
     • (101) Divide A / B
     • (110) Add A + B
     • (111) A XOR B

4. Bus Selection

   • Control select lines determine which component is connected to the bus:
     • (000) Memory
     • (001) AR
     • (010) PC
     • (011) AC
     • (100) DR
     • (101) TR
     • (111) IR

Then we enhance the basic computer by adding a control unit, implementing the PC register as a counter and implementing a specific program.

5. Control Unit

   • Add decoders, sequence counters, and logic gates to implement the control unit.
   • Ensure all unused control signals are set to zero for stability.
   • Redesign timing diagrams for instructions as registers do not have clear or increment functionalities (or design registers to include these features).

6. Program Assembly

   • Implement the following program:

     int A, B, C, i; // variables
     for (i = 0; i < 3; i++) {
         C += A / B;
         A += A * B;
     }

   • Example expected outputs after 3 iterations: A = 432, B = 2, C = 104.

7. Instruction Set

   • Implement the following instructions: LDA, MUL, ADD, STA, DIV, ISZ, BUN.
   • Use BSA opcode for MUL and AND opcode for DIV.
   • Ignore HLT and interrupt instructions; use normal instruction cycle.

How to Install

1. Clone the Repository:

   git clone https://github.com/yehiarasheed/Basic-Computer-Simulation.git
   cd Basic-Computer-Simulation

   This command downloads a copy of the repository to your local machine and navigates into the project directory.

2. Install PSpice: Download and install PSpice from the official PSpice website. PSpice is essential for running and modifying the simulation files.

3. Open the Project in PSpice:

   • Launch PSpice.
   • Navigate to the project files by selecting File → Open and choosing the appropriate .circ file from the cloned repository.

Dependencies

This project relies on the following dependency:

• PSpice: The application required to run and simulate the basic computer architecture.

Make sure PSpice is installed and correctly configured on your machine to execute the simulation files in this project.

---