WIP "Console" processor, written in C#

I decided I wanted to make a console-like system. So, I started planning & creating it in c#. Currently, all that it is is a processor of sorts. It reads all bytes from a file (R:disk00), and then executes them, somewhat like a CPU. display.pyw is a simple pygame application which reads R:disk01 and displays the characters therein.
(To run this, you need to have an R: drive mounted and at least disk00 and disk01 files. disk01 should be 512 bytes long.)

I’ve never actually done anything like this, so I’m proud of this project. Currently, though, I want it to be faster. Since eventually, I’ll be creating full games in this, I need it to be fast. I’ve made it fairly fast, but I’m sure that it can be improved. Also, my code is normally overengineered, so I’m sure there’s a bit I can improve.

I can’t exactly paste 600+ lines of code here, so I’ll link the Github repo. This is my first post here so I’m hoping I didn’t mess it up. Thanks!