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Matchie and Pixel 79.5



I've restarted work on my Matchie game after finding a solution for an annoying TIA quirk. Although the 2600 shows 160 pixels across the screen, SCORE mode can corrupt the color of the last HALF-pixel on the left half of the screen. If the last playfield pixel on the left half of the screen is set, the 77th through 80th pixels should appear in P0 color. Unfortunately, the right half of that playfield pixel will show up in an indeterminate color which may be affected by COLUPF even though the playfield should appear entirely in P0 and P1 colors.


For quite awhile i shelved the game because I couldn't get it to look good on a real 2600. Finally, though, I figured out the solution: display Missile 0 at pixel 79 on any scan line where that playfield pixel is set. Problem solved.


I'm curious, though, does anyone know any other race conditions that can cause Atari 2600 to be "split"?


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Here's a WIP version which will work nicely on emulators but show the pixel 79.5 problem on a real machine. There are some odd quirks in this version, and parts of the code need cleaning up, but I'm a bit more motivated since I know the column-79.5 behavior is fixable.


The goal of the game is to remove all the colored blocks. Blocks may only be removed in groups of two or more same-color blocks touching horizontally. To remove a group of blocks simply move the cursor over any block in the group, then press and release fire.


There are 10,000 starting configurations of blocks. To choose one, press SELECT, move the joystick up/down/left/right, and then push RESET. The fire button should work there but doesn't.


There are two styles of color display. Use Left Difficulty to select.


At present, there is a MAJOR cheat enabled. Pushing and holding the fire button while moving the joystick will allow the player to "paint" blocks on the screen. This will obviously not be in the real game, but allows for testing of the block-removal logic.

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Ooh - Same Game :ponder:


Blocks may only be removed in groups of two or more same-color blocks touching horizontally.

I was able to remove groups of 2 blocks that were touching vertically as well as horizontally.

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I was able to remove groups of 2 blocks that were touching vertically as well as horizontally.


Sorry. Groups touching horizontally or vertically (but not diagonally). These groups may be of any shape subject to that criterion. Removing a few large groups will award many more points than removing many small ones, so one should try to consolidate blocks of one color so that many can be removed at once. With the scoring in its present form, 10,000 is a pretty decent score.

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Very nice game! I notice the title screen says 2005 :ponder:


Yes, well I started the game over a year ago, and then decided the nasty seam at pixel 79.5 made it too annoying to play on real hardware so I shelved it. Anyone who tries the version posted here on real hardware will likely see the problem (though I'd be interested in reports either way). I have a version that fixes that problem but it won't work on the common release of Z26 (workarounds for a Z26 bug and the hardware bug each take a few cycles, and I fall a little short of doing both; I'll pobably just include both kernels in a later version and have the cart auto-select, or else find a cycle somewhere I can eliminate since I'm only one short on the worst case. I could perhaps eliminate a WSYNC except the problem scan line takes variable time.


Incidentally, the kernel concept was illustrated on one of my early posts here. http://www.atariage.com/forums/index.php?showtopic=70712 to be precise.


Also, ironically, just before I found the (what should have been obvious) solution to the SCORE mode bug, I came up with a different kernel idea which in some ways I like better than this one, though this game is close enough to completion I may as well finish it. But watch for MatcHex in the near future. :lol:

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