Video Chess

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VideoGameCritic
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Video Chess

Postby VideoGameCritic » January 28th, 2015, 6:52 pm

I was just reading this story about how somebody programmed a game of chess in just 487 bytes!  That is remarkable, and it makes me wonder if I should revisit some of the classic video game chess titles like Video Chess for the Atari 2600.

Are they still enjoyable, or is the only thing left their novelty value?

Sut1
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Video Chess

Postby Sut1 » January 28th, 2015, 7:14 pm

I think you should hook up Atari 2600 chess and Channel F chess and play them off against each other and see who wins !

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Video Chess

Postby VideoGameCritic » January 28th, 2015, 8:08 pm

[QUOTE=Sut]I think you should hook up Atari 2600 chess and Channel F chess and play them off against each other and see who wins ! [/QUOTE]

This is actually a really interesting idea!

Astrosmasher1
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Video Chess

Postby Astrosmasher1 » January 28th, 2015, 9:15 pm

An Awesome idea.  Then at the end of it you can see if any of them gain sentience and start calling themselves Skynet.

goldenband1
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Video Chess

Postby goldenband1 » January 28th, 2015, 11:33 pm

[QUOTE=videogamecritic]Are they still enjoyable, or is the only thing left their novelty value?[/QUOTE]

Depends on whether you enjoy chess games to begin with -- but if you do, then sure, there's something worthwhile about all of them.

Actually old chess carts can be more fun than modern programs, which are so lethally effective with tactics and raw calculation that you literally have no chance to beat them unless they dumb themselves down -- and the way they do that usually feels unnatural, and bears no resemblance to a human player. At least you have a chance against the Intellivision or NES, even when each is at its best. 

I've been playing my way through many older chess games, and have beaten most of the console titles up through the 16-bit era (plus Battle Chess for 3DO, which stinks). When you come down to it, the only real difference between most of them is playing strength, interface options, and the occasional bug. Otherwise, anything prior to the 32-bit era is in the same ballpark, with the Chessmaster games at the high end of the spectrum.

The Atari 2600 and Intellivision games take insane amounts of time on the highest difficulty, but if you're not playing on the toughest levels (which I like to do, simply so I can say I've beaten each game definitively), it should be possible to get even those games to move within a reasonable amount of time.

I know it's irritating when games take a while to move, but taking a few minutes is normal in chess, and in tournament chess people can spend an hour or more on one move -- if they have the spare time on their clock, that is. It's too bad no games use chess-clock timing, where one side has 15 minutes (or whatever) to play the whole game, and that's it; Chessmaster hints at it, but doesn't implement it formally. 

BTW some folks on AtariAge have pitted console chess titles against each other, with interesting results. I haven't tried the Odyssey 2 one, which has its own dedicated Z80 processor to beef it up, but unfortunately isn't NTSC-compatible. I'd love to try the Channel F one someday.

Bottom line, a reconsideration of Video Chess would be welcome (clunky though it may be), and I'd love to see any others you haven't covered added to the list. The Intellivision's USCF Chess is a classy little package -- they really tried to do a good job -- and I think that's the most notable absence from your list, especially since you're creeping up on a complete Intellivision review library.

scotland171
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Video Chess

Postby scotland171 » January 29th, 2015, 5:22 am

This may be a time to use the Atai flashbacks or emulation. I think the 2600 uses the TIA chip to help which is why you get the screen flickers. I don't recall the flicker on the Flashbacks...even the FB2, but I may be wrong.

There is a fun scene in a comic where a guy is trying to showoff by playing two people at once. The trick is he played white on one board, black on the other....actually he was just acting as a go between and the players were playing each other but did not know. Its cool in that the middleman is guaranteed to come out looking smart with no work involved.

One thing that is neat is that the early programs are so small that it would not have room for a library of openings or endings. The difference in difficulty levels seems to be raw calculations of strength of resultant positIon. Thats great for chess nobodys like me and simulates playing a friendly game. You can try oddball openings, lose initiative or whatever and not get feel like Bambi meeting Godzilla.

What Goldenband has done is impressive. Kudos. I think playing the Fairchild is a great idea but start simple with tic tac toe. How about checkers? The odyssey has a hangman game. Does the Studio II have any of the classics?


Sut1
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Video Chess

Postby Sut1 » January 29th, 2015, 8:02 am

[QUOTE=scotland17]Does the Studio II have any of the classics?[/QUOTE]

Haha the Studio II even messed up with it's obligatory Pong clone, the thought of it trying to play chess makes me shudder. Hell I think it would even struggle with 'Snap'.

SpiceWare1
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Video Chess

Postby SpiceWare1 » January 29th, 2015, 11:17 am

[QUOTE=scotland17]I think the 2600 uses the TIA chip to help which is why you get the screen flickers. I don't recall the flicker on the Flashbacks...even the FB2, but I may be wrong.[/QUOTE]

On the Atari most of the CPU's time is spent shoving data into TIA in order to generate the display scanline-by-scanline.  This slide from my presentation shows the usual program flow:
VCS Program Flow.png 

Game logic usual runs during the 37 scanlines of Vertical Blank and the 30 scanlines of Overscan, 67/262 shows we only get 26% of the CPU time for the game logic.

A typical NTSC game will generate 262 scanlines in total.  You can see this in Stella by hitting COMMAND-L on the Mac or ALT-L on Linux & Windows.  Scanline count and other info will show up in the top-left corner of the window:
Screen Shot 2015-01-29 at 9.52.42 AM.png 

Video Chess needs so much CPU time that they decided to only update the background color, and not even bother with the sync signal, while calculating the next move.  Without the Vertical Sync the Atari's no longer generating a valid video signal.  Older TVs will roll, but you probably wouldn't notice that due to the background color changing all the time.  Newer TVs will think the signal went away and show a "no signal" screen instead.  

In Stella you can see the scanline count goes crazy when Video Chess is calculating the next move:
Screen Shot 2015-01-29 at 9.52.52 AM.png


The benefit of this for Video Chess is obvious - moves can be calculated in 1/4th the time vs if they kept displaying the chess board.

SpiceWare1
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Video Chess

Postby SpiceWare1 » January 29th, 2015, 11:56 am

Since the Atari's video signal is totally under programmer control, a common tradeoff is to shrink the visible portion of the display in order to give more processing time to the game logic.  We've been playing Jr. Pac-man for the HSC over at AtariAge.  The maze is noticeably smaller than other games:
Jr. Pac-Man (1984) (Atari).png 

If you measure out the visible part, you'll get 340 lines.  That screenshot is doubled up, so that's really 170 scanlines - 22 less than the 192 used in the program flow image of my prior reply.  One scan line of time = 76 cycles of 6507 processor time, so:

67*76 = 5092 cycles per frame for game logic of a typical game
89*76 = 6764 for Jr. Pac-Man

Which means Jr. Pac-Man gets 33% more processing time than the typical game.

Sut1
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Video Chess

Postby Sut1 » January 29th, 2015, 3:03 pm

Thanks for the informative post Spiceware, it's very interesting. I'm always amazed at these little tricks to get more out of a consoles hardware.


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