🟦 Blue CPU Interpreter

A TypeScript emulator for the Blue processor described by Caxton C. Foster.

This project aims to faithfully reproduce the behavior of the Blue CPU from the classic book Computer Architecture: A Constructive Approach.

The emulator simulates clock cycles, CPU states (FETCH/EXECUTE), internal registers, and memory, allowing you to load small programs and observe their execution step-by-step.

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📚 Purpose

The goal of this interpreter is to:

• Reproduce the instruction cycle of the Blue processor
• Emulate its internal registers (PC, A, IR, MAR, MBR, etc.)
• Execute programs made of 16-bit words
• Serve as a learning tool for computer architecture, compilers, and CPU design

This project also complements the study of compiler construction — showing how a processor works internally through a clean TypeScript implementation.

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🧩 How it works

The CPU execution follows these steps:

1. A program is loaded into RAM (a Uint16Array of instructions).

2. The CPU enters the main loop.

3. Each cycle calls EmulateCycle(), which:

   • Advances through 8 clock ticks
   • Performs FETCH → EXECUTE

4. After each cycle, register values are printed using DumpRegister().

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🧱 Implemented Registers

• PC – Program Counter
• A – Accumulator
• IR – Instruction Register
• Z – Zero flag
• MAR – Memory Address Register
• MBR – Memory Buffer Register
• DSL, DIL, DOL – Auxiliary 8-bit registers

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📦 Project Structure

src/
 └─ cpu/
     ├─ Cycle.ts
     ├─ Runner.ts
     ├─ Registers.ts
     ├─ Dump.ts
     ├─ Program.ts
     ├─ Nop.ts
     └─ ...
 index.ts

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▶️ Running the project

npm install
npm run dev

Or run it directly using ts-node:

npx ts-node src/index.ts

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🧪 Sample Program

The file Program.ts includes a simple program:

export const program0 = new Uint16Array([
    0xF000,
    0xF003,
    0xF000,
    0xF005
]);

You run it with:

RunProgram(program0)

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🔍 Debug Output

During execution, the CPU dumps the register state:

PC:0001 | A:0000 | IR:F000 | Z:0000 | MAR:0001 | MBR:F000 | DSL:00 | DIL:00 | DOL:00

This allows you to visually track each step of the CPU cycle.