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KevKelley

Intentional Glitches

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I accidentally screwed up on a line of code garbling up my lives counter. 

 

A little while back I was playing around with code that had an unintended consequence of reversing my playfield and having the sprites scroll down all garbled, kind of like in the Matrix.

 

Got me wondering...

 

Had anybody found any interesting graphical (or other types) of glitches that had a cool effect? 

 

Is it worth it to explore these issues as a way to add some special effects and is it worth it with time and space restrictions?

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That code you didn't expect could be an Fx routine  in your next game.

 

In the 80's we used artifact colors by exploiting NTSC "glitches" that PAL color circuitry lacks. 

 

Today a concern might be weather your game will still run on the Flashback Portable or the Retron77 as well as a classic Atari console.

 

bitd we were careful to make sure our software would still run without extra features from glitches when they weren't available. imo that's still a good idea today so that folks can enjoy the games on as many Atari platforms as possible.

 

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40 minutes ago, Mr SQL said:

That code you didn't expect could be an Fx routine  in your next game.

 

In the 80's we used artifact colors by exploiting NTSC "glitches" that PAL color circuitry lacks. 

 

Today a concern might be weather your game will still run on the Flashback Portable or the Retron77 as well as a classic Atari console.

 

bitd we were careful to make sure our software would still run without extra features from glitches when they weren't available. imo that's still a good idea today so that folks can enjoy the games on as many Atari platforms as possible.

 

I hadn't thought of Flashback or Retron compatibility with glitches.  I had only experienced it in Stella and I corrected the issue before trying it on hardware but I noticed no cycle issues and it didn't impact the main loop (since it was in the Game Over screen).  Currently I only test on the AFP and hardware.  I have a FB9 but I hadn't tested on that yet but you make a great point and I should probably start testing on more options as that would increase the amount of potential enjoyment.

But if all works well that would be pretty neat.  I didn't stick with it since the effect didn't quite fit with my game. It didn't make sense why the screen would constantly redraw backwards and the sprites act all Matrix-like for a warehouse game.  I do think it would be more of a pain trying to discover such glitches and then see if they a) fit in with the game and b) work. 

 

I did wonder if there were any known glitches.  In Crossdock, I use pfcolors and pfheights.  I forgot about defining the color and changed some things that resulted in the top row changing colors.  RT's site mentioned it was a known bug with the top row.  I had actually liked it and incorporated it into my game but I as wondering about things that might have been more impressive than a row changing colors, more like the graphical issues I experienced.

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9 hours ago, KevKelley said:

I hadn't thought of Flashback or Retron compatibility with glitches.  I had only experienced it in Stella and I corrected the issue before trying it on hardware but I noticed no cycle issues and it didn't impact the main loop (since it was in the Game Over screen).  Currently I only test on the AFP and hardware.  I have a FB9 but I hadn't tested on that yet but you make a great point and I should probably start testing on more options as that would increase the amount of potential enjoyment.

But if all works well that would be pretty neat.  I didn't stick with it since the effect didn't quite fit with my game. It didn't make sense why the screen would constantly redraw backwards and the sprites act all Matrix-like for a warehouse game.  I do think it would be more of a pain trying to discover such glitches and then see if they a) fit in with the game and b) work. 

 

I did wonder if there were any known glitches.  In Crossdock, I use pfcolors and pfheights.  I forgot about defining the color and changed some things that resulted in the top row changing colors.  RT's site mentioned it was a known bug with the top row.  I had actually liked it and incorporated it into my game but I as wondering about things that might have been more impressive than a row changing colors, more like the graphical issues I experienced.

Yes the Cosmic Ark effect discovery was unexpected - many new discoveries happen unexpectedly even when they are not from a glitch.

 

I think the Atari's unique architecture has potential waiting to be explored and that we will see many new exciting discoveries :)

 

Though now antique, the Classic Tube Television also has potential for new discoveries with Atari because of being tightly coupled to race the beam via the TIA.

 

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17 hours ago, KevKelley said:

Had anybody found any interesting graphical (or other types) of glitches that had a cool effect?

Rob Fulop had a bug during Missile Command creation. This bug is the basis of Cosmic Ark's starfield.

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Wanted to share this example of an interesting glitch with cool graphics Fx I discovered unintentionally with BASIC in the 80's and shared in a magazine at the time.

 

This thread reminded me about this program - hopefully someone in the CoCo community will upload a video. 

 

 

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There is another fun glitch with BASIC programming present in ARKANOID_AIRHEADS that created more versions of the game with alternate palettes depending upon which console or emulator you play on -

ARKANOID_AIRHEAD_FLASHBACK_PHAT_BINARY.thumb.jpg.f6fd0bd860a4ee9068c0cdc4e797563e.jpgARKANOID_AIRHEAD_FLASHBACK_EMU_ANOMALY.bin

 

The BASIC program is the same, the first version is the SuperCharger version which looks the same on all consoles and emulators.

 

The other three screens show the three different game palettes present in the same CBS RAM binary recompiled with Flashback BASIC to play on the Flashback Portable console, also shown on the Retron-77 console, and Classic consoles with an Uno or Harmony cart and Javatari (used an emu pic for all three to exclude CRT differences).

 

To create the phat-binary with multiple game palettes depending on the Atari console or emulator platform used, I leveraged a glitch where programmers had different ways to initialize the 256 bytes of CBS RAM - some would float the bits high, some would float them low and some would randomize it to some degree.

 

The latter may be the correct model, I remember the RAM on the CoCo being randomized on powerup. The 256 byte CBS RAM chips used in the 80's may have retained data for a duration or were cleared or randomized - the RAM was tested with a dumper, but the hardware might also affect the outcome.

 

Since this discrepancy exists it can be used to create phat binaries like the phat carts from bitd that had different versions of the game depending upon which system you plug the cart into: 

 

Here's are some interesting videos of a phat ARKANOID cart that was released with multiple versions of ARKANOID in the 80's by programmer Steve Bjork:

 

Stevie Strow discusses the phat cart and plays the first version of ARKANOID in the cart.

@AtariLeaf plays second version with the enhanced colors.

 

In this case both ARKANOID binaries were actually present on the phat cart and which system would determine which version could be played.

 

When leveraging glitches and idiosyncrasies present in the hardware and firmware being different across consoles and emulator platforms, the system determines the different version from the same binary based on the glitch :)

 

Only one of the three alternate palette versions of Arkanoid AirHead may be correct, but it's a lot of fun to have all three versions present and see them transform on the different Atari consoles the game is played on!

 

 

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