A very simple 8-bit CPU simulator

A very simple representation of an 8-bit CPU (I guess you could also say it's a virtual machine). It has two registers, register_a and register_b, and the following instructions:

Opcode	Description
0	No operation
1	Set value in register A
2	Set value in register B
3	Set memory address to register A
4	Retrieve position stored in register A and store the item at that position into register A
5	Add values in registers A and B, storing the result in register A
6	Subtract value in register B from register A, storing the result in register A
7	Jump to a position in the memory
8	Jump to a position in the memory if the value in register A is zero
9	Print the value in register A
10	Print the character corresponding to the ASCII value in register A
11	Halt and print a new line
12	Increment value in register B by 1

Example

The main function in the main.rs file includes an example program that prints out the string "Hello, World!".

Future plans

It would be cool to expand the capabilities of this CPU later. Here are some things that I have in mind:

• Additional instructions such as multiplication, division, logical operations, shift operations, etc.
• A flags register that gets updated after each operation. These could include zero flag, carry flag, sign flag, etc.
• Error handling for invalid opcodes, memory out of bounds access, underflow/overflow of values, etc.
• A simple assembler that can take in a program written in an assembly-like language and output the corresponding Vec<u8> that can be executed by the CPU.
• A GUI that visually represents the registers, memory, and the operations being performed, perhaps even allowing you to step through the execution one operation at a time.
• Unit tests.