MAMEWorld Forums - Programming - Re: Writing My Own Emulator From Scratch

Okay, so it's been an interesting past couple of days.

Let me review what's happened so far:

1. We've identified the game we wanted to emulate.

This was centipede. I do have to admit that I actually picked the processor first and then searched around for games that I liked that used that processor.

2. We've located schematics for the game.

3. We've located tons of information on the processor we'll be using. This thing is documented all over the place and their are lots of "emulators" for it out there already.

4. We've begun analyzing the architecture for the game.

This has been the toughest part (for me). If someone were to ask me how to do this then, at this point, I would end up pointing them to the internet. For example, we identified the speed of the crystal, but I don't know how I knew it was the crystal from the schematic. Maybe the schematic I have just isn't the best. (For example, the CPU is on one corner of one page and the page with the crystal is on another corner of another page. This made (makes?) it difficult for me anyway to actually trace where the pin 37 on the 6502 is actually coming from).

I've also glanced ahead just a tiny bit. Even though I'm nowhere near ready to start coding, I still wanted to identify the language I would use to code the whole project. The majority of time it is probably recommended to use C or assembly. But I've decided to see how Delphi will work (Delphi 2005 specifically). I really like using Delphi to prototype applications and there's a wealth of free components out there that can make your life easier. After deciding this, I also came up with a silly name for the project. So for now, it'll be called Delphipede!

I then wanted to really decide if I wanted to write my own 6502 emulator or if I just wanted to use something already written. Two things came into play here. The goal of the project is to learn, but at the same time I still want to keep things simple. So what I'm going to do to start with is go in the middle. I've found the source code to a 6502 emulator written by Neil Bradley. It's written in C. Since, I'm going to use Delphi, I'll be converting this C to Delphi which will give me a real good chance to understand everything that is going on.

ArcadeGamenut