A JavaScript Gameboy Emulator, Detailed In 8 Parts

Two9A writes "JavaScript has shed its image of being a limited language, tied to DOM manipulation in a browser; in recent years, new engines and frameworks have given JS a reputation as a language capable of bigger things. Mix this in with the new elements of HTML5, and you have the capacity to emulate a game console or other system, with full graphical output. This series of articles looks in detail at how an emulator is written in JavaScript, using the example of the Gameboy handheld: starting at the CPU, and (as of part 8) running a copy of Tetris."

Comments

There are already tons of Game Boy emulators...

[Anonymous Coward]

...but whenever I use one, I can't help but think "I sure wish this was written in Javascript, so there wouldn't be any way to save my game. Saved games are for pussies. And sure, it wouldn't support sound, but who needs that when you've got the beautiful noise of your computer fans running on full blast, thanks to its excessive CPU usage!"

Your jokes are out of date.

[pavon]

Both sound and client-side data storage are features of HTML5.

Sound?

[Mr. Sketch]

I'm curious how he plans on handling dynamically generated sound from the GB ROM. Doing CPU and Graphics are usually the easy parts of emulating, but getting smooth dynamic sound without much latency is the challenge I've had to deal with when doing web-based emulators. Most web-based systems are designed to load a static set of sounds from a server, not dynamically generate them in the code.

Flash 10 provides some dynamic sound capability, but it has a rather large latency (~250ms). I blogged about this while writing my NES emulator in flash.

I read through these articles hoping for some insight on dynamically generated sound, but it doesn't look like he's gotten that far.

... why?

[Mongoose Disciple]

I've said it before, and I'll say it again:

You can write damn near anything in JavaScript if you really want to, but the better question is if you should.

And yes, that includes half (but only half!) of the stuff you'll find done in JavaScript in web apps.

Ode to JavaScript

[CobaltBlueDW]

JavaScript is truly a horrifyingly discussing,
intrinsically retched,
soul darkening, succubus from the abysmal depths of conceivable depravity.

To know its stench
is to know the crippling limitations of our future.
To recognize its sloven decadence
and remain indifferent
is to burn the righteous.

No faith,
however moving and spectacular,
could light a path of its continuation.
No argument,
however complex and equivocated,
could elevate such a encumbering and wearisome burden.

There is no failure so inadequate,
or stagnation so bereft of utility
as that of JavaScript.

Thankyou.

Vic20 in Javascript

[Anonymous Coward]

And here's a Vic20 emulator in Javascript HTML5
http://www.mdawson.net/vic20beta/vic20.php

Compile the JavaScript

[Anonymous Coward]

Saying that you shouldn't write this in JavaScript because of the limitations of JavaScript in web browsers is like saying people shouldn't write Apps in Java because Applets are limited. It's not JavaScript that is the problem per se, but the limitations of the Interpreter. If you want to write something like this in JavaScript, you should consider compiling the JavaScript instead.

Using the Unity Framework ( http://unity3d.com ), you could write the emulator in JavaScript, compile it, and have a cross platform emulator that would work on Mac, PC, Wii, Iphone, Android, and PS3 with hardware accelerated 3d, support for sound, etc. Something like 20-25 of the top 100 Iphone Apps were made using Unity, and it is a pretty good platform for making 3d games.