6 ms·

16-Bit VM in JavaScript

84 points by mzehrer 9y ago

pjmlp 9y ago
Very interesting read and props for choosing opcode D, S.
- FrancisStokes 9y ago
  Thanks, I've had mixed feedback about that choice!
mysterydip 9y ago
Something I've always wanted to do (16 bit as well, even) but never got around to. Thanks for the writeup!
jasonhansel 9y ago
Congratulations! I've been working on a similar (though less well-documented) project in Rust: https://github.com/jasonhansel/kineticvm https://github.com/jasonhansel/kineticvm
- FrancisStokes 9y ago
  Ah very cool! Rust seems like an awesome language, especially for something like this. I'l going to take a dive into your project at some point in the week
- carussell 9y ago
  Props for choosing `->` instead of either of the historical mistakes `opcode s, d` or `opcode d, s`.
orionblastar 9y ago
This is in a way that they make emulators in Javascript like that too? Might be possible to emulate Mame and Mess machines if they haven't already?
- khedoros1 9y ago
  Yes, there are some similarities to how you would write an emulator for a real piece of hardware. It would be possible to write an emulator for whatever hardware you can find enough information about.
- FrancisStokes 9y ago
  Indeed, the core concepts are essentially exactly the same. This is a lot simpler of course because it doesn't need to do anything with drawing or sound. I really like this project https://github.com/juchi/gameboy.js/ https://github.com/juchi/gameboy.js/ . I'd like to do something similar myself but more in the coding style I've used on the 16-bit VM.
m1dnigh7 9y ago
Is this a VM in the sense the JVM is a VM, or is it a VM in the sense of a CPU emulator? It seems to be the former, but I'm not well read in VM implementation.
- gmiller123456 9y ago
  That's a very fuzzy, if not non-existent, distinction. The only real difference is the designers' original intention. Of course the Java VM was originally only destined to exist only in software, but hardware versions do exists [1]. And of course x86 was always destined for hardware, but there's more software implementations of that than can be counted. There's also a third type in the LLVM sense, where the VM is just an intermediate step in compiling from a high level language down to machine code. And that's where the JVM (mostly) falls today. The VM described in the OP could easily fit in any of the three. [1] http://www.jopdesign.com/ http://www.jopdesign.com/

84 points by mzehrer 9y ago

pjmlp 9y ago

Very interesting read and props for choosing opcode D, S.

FrancisStokes 9y ago
Thanks, I've had mixed feedback about that choice!

mysterydip 9y ago

Something I've always wanted to do (16 bit as well, even) but never got around to. Thanks for the writeup!

jasonhansel 9y ago

Congratulations! I've been working on a similar (though less well-documented) project in Rust: https://github.com/jasonhansel/kineticvm https://github.com/jasonhansel/kineticvm

FrancisStokes 9y ago
Ah very cool! Rust seems like an awesome language, especially for something like this. I'l going to take a dive into your project at some point in the week
carussell 9y ago
Props for choosing `->` instead of either of the historical mistakes `opcode s, d` or `opcode d, s`.

orionblastar 9y ago

This is in a way that they make emulators in Javascript like that too? Might be possible to emulate Mame and Mess machines if they haven't already?

khedoros1 9y ago
Yes, there are some similarities to how you would write an emulator for a real piece of hardware. It would be possible to write an emulator for whatever hardware you can find enough information about.
FrancisStokes 9y ago
Indeed, the core concepts are essentially exactly the same. This is a lot simpler of course because it doesn't need to do anything with drawing or sound. I really like this project https://github.com/juchi/gameboy.js/ https://github.com/juchi/gameboy.js/ . I'd like to do something similar myself but more in the coding style I've used on the 16-bit VM.

m1dnigh7 9y ago

Is this a VM in the sense the JVM is a VM, or is it a VM in the sense of a CPU emulator? It seems to be the former, but I'm not well read in VM implementation.

gmiller123456 9y ago
That's a very fuzzy, if not non-existent, distinction. The only real difference is the designers' original intention. Of course the Java VM was originally only destined to exist only in software, but hardware versions do exists [1]. And of course x86 was always destined for hardware, but there's more software implementations of that than can be counted. There's also a third type in the LLVM sense, where the VM is just an intermediate step in compiling from a high level language down to machine code. And that's where the JVM (mostly) falls today. The VM described in the OP could easily fit in any of the three. [1] http://www.jopdesign.com/ http://www.jopdesign.com/