[Staff] Vinegar: CHIP-8/SCHIP interpreter ('emulator')

Post by **benryves** » Mon 27 Feb, 2006 12:16 pm

Yet another (*cough*) side project; this time it is a genuine side project as I only worked on it for a couple of days

Download binaries for TI-83/TI-83+
Documentation

Vinegar is a simple CHIP-8/SCHIP interpreter with a range of options; it should run most CHIP-8 games fine. SCHIP games are cropped to 96x64 (pan-and-scan with the arrow keys) - I'm up for ideas on how to display the 128x64 screen! My quick-and-dirty scaling methods were very ugly, so I removed them from this beta.

Please note that because of the way this works it can potentially cause RAM clears. I have done my best to catch any errors, but this is still in beta. It does check all bounds before writing to memory, and has a built-in error system.

None of the games I have played with it have crashed my calculator, though.

Post by **tr1p1ea** » Mon 27 Feb, 2006 12:29 pm

So ... many ... projects ... in ... such ... a ... short ... amount ... of ... time!

Very hard to keep up with you ben!

CHIP-8 is an awesome idea, i vaguely remember someone talking about it a while ago ... but maybe that was for GBA instead.

Wow! - There are a lot of games included!

.

kalan_vod · Post by **kalan_vod** » Mon 27 Feb, 2006 12:54 pm

Really nice Ben, yeah I remember someone talk of this also. This looks amazing!

GuillaumeH · Post by **GuillaumeH** » Mon 27 Feb, 2006 1:26 pm

Awesome, this means a new wave of games is coming to our Tis

Good job benryves, you're really on fire these days.

Post by **kv83** » Mon 27 Feb, 2006 1:40 pm

wow very nice

Post by **benryves** » Mon 27 Feb, 2006 1:45 pm

GuillaumeH wrote:Awesome, this means a new wave of games is coming to our Tis

The problem is that for SCHIP games, you can't see what you're doing

For some games (eg Ant) this isn't much of a problem. Joust can get annoying, as you start off screen. Blinky (the SCHIP version) is not great to play, either.
Note also that some of the ROMs included in the package are useless (X-Mirror, IIRC?). I just batch converted a load of them, most work but I haven't tried them all.

*shakes fist at TI for giving the 83 series 96-pixel wide screens*

Timendus · Post by **Timendus** » Mon 27 Feb, 2006 2:37 pm

Like I spammed in the Emerson thread: Bloody amazing!

I think you've already earned the titles "best programmer" and "most active programmer" for 2006

Post by **benryves** » Mon 27 Feb, 2006 2:53 pm

Timendus wrote:I think you've already earned the titles "best programmer" and "most active programmer" for 2006

Heh, thank you

One thing I have noticed; I've been looking for some more documentation on CHIP8 (for better information about the way it works) - according to this site, FX55 and FX65 need to modify I; they don't in my implementation.

I'd also like to rewrite the sprite routines; they're currently mutilated versions of ionPutSprite and ionLargeSprite, and don't wrap in the same way as most PC implementations do.

A CHIP-8/SCHIP interpreter is not a difficult project, but I wanted to give it a go as a bit of fun.

Post by **kv83** » Mon 27 Feb, 2006 3:19 pm

What consoles/pc's did use chip-8?

Post by **benryves** » Mon 27 Feb, 2006 3:24 pm

kv83 wrote:What consoles/pc's did use chip-8?

Originally, COSMAC VIP and Telmac 1800.
However, the SCHIP extensions were developed for the HP48, and since then there has been an interpreter for pretty much every platform under the sun, though it appears that the only TI one was for the TI-85, by Andreas Ess.
The TI-85 has a 128x64 display, so has the benefit of not having to crop the display and can double the pixel size for the regular CHIP-8 mode to implement half-pixel scrolling.

kalan_vod · Post by **kalan_vod** » Mon 27 Feb, 2006 4:00 pm

Well none the less, this is a great job! Btw could you not just adapt the screen size to fit that of the 83+? Like instead of using the way you have it, nake it where the screen is full. So when your playing joust you could just "blow" up the screen. I am unsure if I am making myself clear...Let me know if I am not.

Post by **benryves** » Mon 27 Feb, 2006 4:14 pm

kalan_vod wrote:Well none the less, this is a great job! Btw could you not just adapt the screen size to fit that of the 83+? Like instead of using the way you have it, nake it where the screen is full. So when your playing joust you could just "blow" up the screen. I am unsure if I am making myself clear...Let me know if I am not.

Do you mean scaling (shrinking) the screen?
I tried using 3 different approaches; setting the LCD into 6bpp mode and shifting each byte right was very ugly but fast; doing a full scale "proper" was very slow and still very ugly (both methods lose pixels). The best looking method was to scale the entire thing down to 50%, but add an offset of either one x or one y (so four different frames) each loop, creating a flickery greyscale view. For some games this looked OK, for others (such as Ant) it made the graphics a horrible mess.
In the end, I removed that code completely and just use the pan-and-scan method.
One method I haven't tried would be to work out where the last sprite was drawn, and to scroll the screen towards it if it was off-screen.

kalan_vod · Post by **kalan_vod** » Mon 27 Feb, 2006 4:20 pm

Well I just meant that could you fill the screen. Like not shrinking it 50% but shrinking it 75% or so?

Post by **benryves** » Mon 27 Feb, 2006 4:27 pm

kalan_vod wrote:Well I just meant that could you fill the screen. Like not shrinking it 50% but shrinking it 75% or so?

That's what I tried. The problem is that you lose pixels in doing so; if you look at the SCHIP "Blinky" (Pacman) you'll see the dots and walls are one pixel thick and they end up being erased.

CoBB · Post by **CoBB** » Mon 27 Feb, 2006 4:31 pm

Blasphemy! Screenshot made with TISShot!