Z80 Emulator - Personal Research Project

This project is a simple Z80 CPU emulator written in C++. It is part of a personal research project into how emulators work and how one might emulate hardware such as a CPU, memory, and basic functionality. This project uses the Z80 processor, which was popular in early computers and calculators like the TI-83.

The emulator includes a command-line interface (CLI) for interacting with the emulation, loading programs, stepping through instructions, displaying registers, and even performing simple calculations using a basic arithmetic evaluator.

Note: A graphical user interface (GUI) using ImGui and more complex mathematical functionality (multiplication and division) will be added in future updates.

Features

• Z80 CPU Emulation: Emulates basic Z80 instructions such as LD, ADD, XOR, RET, and more.
• Memory Management: Provides basic memory functionality for loading programs into memory.
• CLI Interface: Offers an interactive CLI for loading programs, running or stepping through the CPU, viewing registers, resetting the emulator, and performing basic arithmetic operations.
• Arithmetic Evaluator: Includes a simple calculator that supports addition and subtraction of integers and floating-point numbers. Future updates will support multiplication (*) and division (/).

Project Structure

• main.cpp: Entry point for the program.
• CPU.hpp/CPU.cpp: Handles the Z80 CPU emulation.
• CLI.hpp/CLI.cpp: Provides the command-line interface for interacting with the emulator.

Setup (Visual Studio 2022)

Prerequisites

• Visual Studio 2022: You need Visual Studio 2022 installed with C++ development tools.

Opening the Project in Visual Studio

1. Clone the repository or download the source files.
2. Open Visual Studio 2022.
3. Open the .sln project file in Visual Studio 2022.

Building and Running

1. Set the build configuration to Debug or Release.
2. Press Ctrl + F5 to build and run the emulator in the console window.
3. You can interact with the emulator using the CLI commands described below.

CLI Commands

Below is a list of available commands that can be used within the emulator's CLI:

1. load

Loads a program into the emulator's memory at a specific address.

Syntax:

load <hex_program> <start_address>

• <hex_program>: A string of hexadecimal values representing the program (e.g., 3E42420680C9).
• <start_address>: The memory address where the program should be loaded (in hex).

Example:

load 3E42420680C9 0000

This command loads the following program at address 0x0000:

• LD A, 0x42
• LD B, 0x42
• ADD A, B
• RET

2. run

Runs the loaded program continuously until the program ends or encounters a RET instruction.

Syntax:

run

Example:

run

This will start executing the loaded program from the program counter (PC).

3. step

Executes a single instruction from the program and updates the registers.

Syntax:

step

Example:

step

This will execute one instruction and print the current state of the CPU after execution.

4. registers

Displays the current values of the CPU's registers, including the program counter (PC), stack pointer (SP), accumulator (A), and general-purpose registers.

Syntax:

registers

Example:

registers

This will output the current values of all CPU registers in hexadecimal format.

5. reset

Resets the CPU registers and clears memory.

Syntax:

reset

Example:

reset

This will reset the emulator to its initial state.

6. calc

Performs basic arithmetic calculations using addition and subtraction with integers or floating-point numbers.

Syntax:

calc <expression>

• <expression>: A mathematical expression containing numbers and +/- operators. You can use both integers and floating-point numbers.

Example:

calc 5 + 3.2 - 1.1 + 6

This will output:

Result: 13.1

7. exit

Exits the emulator.

Syntax:

exit

Example:

exit

This will terminate the emulator and return to your terminal.

Example Workflow

1. Load a program:

   load 3E42420680C9 0000
   

   This loads the program at address 0x0000.

2. Step through the program:

   step
   step
   

3. View the register values:

   registers
   

4. Run the program continuously:

   run
   

5. Perform a simple calculation:

   calc 5 + 5 - 2
   

6. Reset the emulator:

   reset
   

7. Exit the emulator:

   exit
   

Future Work:

This project is part of ongoing research. Future work:

• Adding a GUI: A graphical user interface (GUI) using ImGui will be added in a future update.
• More Complex Math: Support for multiplication (*) and division (/) will be added to the calculator program soon.
• Support for more Z80 instructions.
• Implementing more accurate timing and interrupts.
• Adding memory-mapped I/O and display simulation.
• Improving the CLI with additional commands for debugging.
• External GUI for displaying CPU Calls and Memory R/W actions.

License

This project is for educational and research purposes only.