Odyssey 2: Under Appreciated?

[jbanes]

So can you explain very briefly for all of us non-techies why there is virtually no flicker or slowdown in O2 games, even when the action is lightening fast (Killer Bees, Attack of the Timelord) and even when the built in character set is not being used?

 

I'm not sure that I'm the best person to answer this, given that I currently know jack-all about the O2's rendering hardware. However, I can make a few generalizations.

 

First and foremost, as the Killer Bees programmer explained in an interview, speed is merely an illusion. If you want something to go faster, merely move it more pixels per frame. The only tradeoff is in the smoothness of the movement. Large jumps can occasionally become detectable by the human eye. Thankfully, television screens run at 60FPS interlaced. Far above a frame rate that humans can see, but bordering the edge of what the brain can perceive. So we don't normally notice a bit of oddness in the movement. This can be further obscured by using sudden changes in direction and acceleration to screw up the brains ability to detect where the object *should* be.

 

Secondly, different rendering technologies make for strengths in different areas. In machines like the 2600, it was able to smoothly render a few objects on screen at a time, because the signal generator was capable of converting a few chunks of memory into a partial video signal. The remainder of the signal was just filled in with a solid color. The background ability of the 2600 allowed for that color to switch between two options in increments of 1/20th of the width of your television. (More colors could be shown if you were willing to waste precious CPU power on fiddling with the signal generator.)

 

Something like the Intellivision, however, was able to fill the screen by rendering repetitive chunks of memory for the background, then allowing for 8 more chunks of memory to be arbitrarily tracked and rendered on the screen. The Nintendo did something similar except that it used tiles of multi-colored imagery instead of single-color "on/off" pictures. (You know, the more I think about it, the more I realize that the NES designers must have been Intellivision fans.)

 

The ultimate rendering technology, however, is the framebuffer. By quantifying each pixel into a memory location, the entire screen can be manipulated. The advantage to this is that you can show anything that can possibly be shown by a television monitor. There are no limits on how many objects can be rendered, and there's no difference between the background and the moving objects. It's all the same. The disadvantage to a framebuffer, however, is that it takes an incredible amount of time to move an image from main memory to video memory. For a 16x16 pixel image, that's 256 operations! Now compare that to the sprite hardware of most game consoles where the game merely modifies a single register (1 operation) to point to an image in ROM. That's a big difference!

 

However, if you have enough memory for a framebuffer, then you can also afford to miss a frame. If you don't render the next frame, the video memory still contains the information. Thus the signal generator shows you the last frame until it gets updated. If the CPU is particularly busy and can't update the frame, this will look like the game has slowed down.

 

Now most older consoles didn't use framebuffers due to memory costs. (320x200 at 256 colors is ~62K of memory!) However, they could store data for rendering an entire frame instead of storing only enough for one line. (The 2600 registers had to be updated on each line, or the next line would end up looking just like the previous one.) Once the data was stored like this, then more advanced graphics processors could render a frame of data independent of what the main CPU was doing. Thus the GTIA (Atari 8-bit), MARIA (7800), and PPU (NES) were all capable of missing a frame without failing to display anything. When they missed a frame, they'd appear to "slow down" much in the way that a framebuffer would "slow down".

 

Umm... does that sort of make sense, or is it too technical?

[doug0909]

I'll have to read this after some brain cell relaxation this weekend

But considering the flicker in 2600 games and the slowness and chopiness of some Intellivision games, the O2 designers were doing something right...

[jbanes]

No, "missing your deadline" on the 2600 just causes things to get drawn in the wrong place, or in extreme cases the entire display to get pushed down a scanline or two. In either case, this is symptomatic of a buggy kernel.

 

*sigh* How did I know that was going to bug you? I was trying to keep it simple. If you miss your deadline, what you want to get rendered doesn't get rendered. Thus you can't miss your deadline.

 

Flickering is the VCS's answer to slowdown.

No it isn't. Flickering is the 2600's answer to limited sprite hardware.

 

From the perspective of a non-techie, though, the two are very similar. The 2600 runs out of graphical power before it runs out of CPU power. Other systems run out of CPU power before they run out of graphical power. Thus the tradeoffs are similar, even if they're not precisely the same.

 

Not that I expect you to agree with such an abstract viewpoint.

 

EDIT:

I'll have to read this after some brain cell relaxation this weekend

See? Now we've overloaded the poor smuck's cognitive stack! He's lucky he doesn't have smoke pouring out of his ears!

 

Edited May 12, 2006 by jbanes

[ZylonBane]

The disadvantage to a framebuffer, however, is that it takes an incredible amount of time to move an image from main memory to video memory.

Unless the particular system uses memory-mapped video-- in which case writing to "video memory" takes the same amount of time as writing anywhere else. Of course this still isn't as fast as a sprite-based system.

 

From the perspective of a non-techie, though, the two are very similar.

Perhaps, but the important detail is that they are NOT AT ALL similar. It's like an astronomer telling someone that the sun and the moon are basically the same thing because they both light up the sky. When offering an explanation to someone, the goal should be to clarify their understanding, not confuse it.

[+batari]

3. At the same time, the O2 was capable of more than most people realize. Check out the completed ROM of Tutankham, which blows away the 2600 version. Additionally, you could make strong arguments that O2 Atlantis and Qbert are more playable and fun than the 2600 versions, with some features the 2600 lacks (despite the less detailed sprites). In fact, of games made for both systems, the 2600 only clearly comes ahead on Demon Attack (which is fantastic on the 2600 and just good on the O2), Frogger (no flicker and very playable on the O2 but split into two screens) and Popeye (which is ok on the 2600 and crud on the O2). [super Cobra on the O2 rocks, but it is so different than the arcade and 2600 versions I cannot even consider it the same game.]

Tutankham doesn't scroll like the arcade and 2600 versions do. Honestly, this game is so different that you can't really compare. And I don't see how it's so much more fun than the 2600. The only thing that's really better is the title screen.

 

I agree that Demon Attack and Atlantis are good on the O2, but they are the only good ports. Qbert is OK. Everything else is either so different or just plain awful that you can't even call it a port. Frogger, Super Cobra (taken as a port), and especially Popeye are just plain awful. The 2600 does have bad ports too, but it has many more good ports.

 

I had to chuckle about the suggestion to add kids' rides to Crazy Balloon. In the O2 version, the gameplay makes no sense at all. It's basically impossible to even get past the first screen. What are the rides for again, except to allow the balloon to fly into a wall? The gameplay over aesthetics argument doesn't apply here. Play Manuel's port of the game on the 2600 - it's excellent and needs nothing.

 

The O2 does have good games, but arcade ports are really the O2's weak area. The best O2 games are designed with the O2's hardware in mind.

[Flojomojo]

This non-techie is really enjoying this thread.

 

I'm changing my avatar back to the old Wizard of Odyssey.

[jbanes]

Unless the particular system uses memory-mapped video-- in which case writing to "video memory" takes the same amount of time as writing anywhere else. Of course this still isn't as fast as a sprite-based system.

 

The difference is beside the point since you don't store sprites in the visible buffer. I was speaking only in terms of operations. 256 operations to blit an image is still more than 1. (Or 1 per line if we want to get specific about 2600 hardware.)

 

From the perspective of a non-techie, though, the two are very similar.

When offering an explanation to someone, the goal should be to clarify their understanding, not confuse it.

 

Fair enough. Simplifying for non-techies is a difficult thing to do. If you feel you can do better, please feel free to interject your own explanation.

Edited May 12, 2006 by jbanes

[Thomas Jentzsch]

So Thomas is right, there is no such thing as slowdown in any Atari 2600 game as the game progresses? It's that simple?

Actually, there is one, unreleased homebrew, which is programmed so sophisticated, that it sometimes might suffer some (display) slowdown. It's a non Boulderdash game.

[jbanes]

Actually, there is one, unreleased homebrew, which is programmed so sophisticated, that it sometimes might suffer some (display) slowdown. It's a non Boulderdash game.

 

How interesting.

 

I assume that you're checking every so often to see if the computations need to be split-up between frames?

[doug0909]

"Tutankham doesn't scroll like the arcade and 2600 versions do. Honestly, this game is so different that you can't really compare. And I don't see how it's so much more fun than the 2600. The only thing that's really better is the title screen.

 

I had to chuckle about the suggestion to add kids' rides to Crazy Balloon. In the O2 version, the gameplay makes no sense at all. It's basically impossible to even get past the first screen. What are the rides for again, except to allow the balloon to fly into a wall? The gameplay over aesthetics argument doesn't apply here. Play Manuel's port of the game on the 2600 - it's excellent and needs nothing.

.....

The O2 does have good games, but arcade ports are really the O2's weak area. "

 

1. Unlike Super Cobra, I don't think the lack of scrolling makes Tutankham a new game. That is because you are confined to certain areas anyway until you hit a portal, and the monsters in both versions patrol a limited area. And I think you would be hard pressed to find anyone who has played both versions and doesn't find the O2 version much more fun, as it is far easier on the eyes and (unlike Super Cobra) has the same basic gameplay elements.

 

2. You are half right about Looney Balloon; I have no idea why the programmer made it so hard to get out of the maze (I have gotten to the exit tunnel but never through it). But the problem is the maze design, not the kiddie rides, which do add an interesting element to gameplay as you have motivation to go to screen areas you would not otherwise go to. The motivation? You get points! As with any good game, it taps into the player's greed....

 

3. Arcade ports are the O2's weak area??? I think O2 Turtles is one of the greatest classic 8-bit ports, ever. I have never met anyone who was not impressed by it. And Popeye is the only O2 port that truly sucks....

Edited May 12, 2006 by doug0909

[ZylonBane]

3. Arcade ports are the O2's weak area??? I think O2 Turtles is one of the greatest classic 8-bit ports, ever.

Turtles is good on the O2 because the game design calls for what the O2 excels at-- maze walls and simple moving objects. Note that the enemy beetles are created by flickering (aha!) between two different built-in symbols (the ball and the X, if I recall correctly).

 

The O2 could probably manage a decent version of Venture, or Mappy, or even Elevator Action. But anything that requires a background that can't be represented with lines or huge blocks is pretty much beyond it.

[doug0909]

Maybe the problem with Looney Balloon was they couldn't pull that line back a few pixels so you could get past level 1? Is there some standard Odyssey 2 grid (used in maze games like Turtles and the KC Munchkin games) that doesn't allow you to tweak where the lines go? (Though if that's it, I guess the solution would be to make the balloon bounce a few less pixels.... I bet someone could hack this and make a playable cartridge...)

Edited May 12, 2006 by doug0909

[kirin jensen]

3. Arcade ports are the O2's weak area??? I think O2 Turtles is one of the greatest classic 8-bit ports, ever.

Turtles is good on the O2 because the game design calls for what the O2 excels at-- maze walls and simple moving objects. Note that the enemy beetles are created by flickering (aha!) between two different built-in symbols (the ball and the X, if I recall correctly).

 

The O2 could probably manage a decent version of Venture, or Mappy, or even Elevator Action. But anything that requires a background that can't be represented with lines or huge blocks is pretty much beyond it.

 

Man. Your hostility toward the O2 is mindstunning. "That's only a good game on the O2 because the O2 is good at that sort of game." And Pick Axe Pete sucks because you haven't made past the low 100s.

 

I don't care what it is that makes you like this about the O2. I'm specifically not responding (after this message) to any comment you have to make about the O2, ZylonBane. I no longer care if it's because your father was killed by an O2 or your mother was frightened at the circus by an O2 before you were born or your neighbor's O2 ate your Atari, I just don't.

 

We get it. You HATEHATEHATEHATE the O2. You find inferior in every single way, including several imaginary ones. There's really no more for your 'heroic' services here.

 

Now can you go back to stroking the woodgrain sides of your heavy sixer and whispering 'My precious' and leave the universe alone?

[supercat]

So can you explain very briefly for all of us non-techies why there is virtually no flicker or slowdown in O2 games, even when the action is lightening fast (Killer Bees, Attack of the Timelord) and even when the built in character set is not being used?

 

On the Odyssey2, most games construct screen displays by setting up everything for a frame before the end of vertical blank, figuring out what all needs to happen on the next frame, waiting for the start of the next vertical blank, and then repeating the process. None of the games for that system really 'do' all that much, so there's plenty of time for the game to do all the necessary computations.

 

On the Atari 2600, the processor is usually 100% involved with the display of any part of the screen that isn't just a pattern of repeated scan lines. Even though its CPU is slightly faster than the one in the Odyssey2, it has less time each frame in which it can prepare for the next.

 

It's not really any more work for the Odyssey2 to display custom character shapes than for it to display the built-in ones. Unfortunately, the Odyssey2 is limited to showing four 8x8 custom shape objects on the entire screen. A few cartridges get around this limitation (e.g. Slot Machine can show nine) but if one abides by the documentation the only way to alter any sprite properties mid-frame is to disable all sprites (custom and non-custom) while doing so; this will result in a horizontal area of the screen within which no sprites can appear. Not a problem for Slot Machine, but would be a problem for many other games.

 

BTW, I think UFO! uses three of the custom-shape sprites to show the player's shots (which appear as a single pixel each). I think the bottom of the airplane wing standard shape would also have been usable for such purpose if there had been a desire to use more custom sprites for something else.

[doug0909]

Interesting.... Thanks.... It sounds like, if the O2 only allowed for more custom sprites, it could have done more than any other classic system without the flicker...

[jbanes]

On the Atari 2600, the processor is usually 100% involved with the display of any part of the screen that isn't just a pattern of repeated scan lines. Even though its CPU is slightly faster than the one in the Odyssey2, it has less time each frame in which it can prepare for the next.

 

 

Odyssey2: Intel 8048 8-bit microcontroller running at 1.79 MHz

2600: MOS Technology 6507 @ 1.19 MHz

 

Or are you comparing cycle counts per instruction? (As I said, I know jack-all about the O2 architecture.)

 

Interesting.... Thanks.... It sounds like, if the O2 only allowed for more custom sprites, it could have done more than any other classic system without the flicker...

 

It's kind of the same for the 2600, though. If it had more sprites available, more work could be done. Instead, programmers had to pull tricks like flickering, reusing missiles as sprites, and a repeating-sprites-on-one-line-trick-who's-name-escapes-me-at-the-moment-but-it-was-used-in-space-invaders trick.

[ZylonBane]

We get it. You HATEHATEHATEHATE the O2. You find inferior in every single way, including several imaginary ones. There's really no more for your 'heroic' services here.

Is it just my imagination, or is Kirin being a bit... insane?

 

It sounds like, if the O2 only allowed for more custom sprites, it could have done more than any other classic system without the flicker...

There would still be the problem of its very low playfield resolution. Without a higher playfield resolution, even a straight port of Pac-Man is impossible.

[+batari]

On the Atari 2600, the processor is usually 100% involved with the display of any part of the screen that isn't just a pattern of repeated scan lines. Even though its CPU is slightly faster than the one in the Odyssey2, it has less time each frame in which it can prepare for the next.

 

 

Odyssey2: Intel 8048 8-bit microcontroller running at 1.79 MHz

2600: MOS Technology 6507 @ 1.19 MHz

 

Or are you comparing cycle counts per instruction? (As I said, I know jack-all about the O2 architecture.)

The 8048's instructions all take one or two cycles each, while on the 2600, they take 2-7 cycles. But, suppose you want to do some calculation on a 6507. Chances are, you will need many more instructions to perform the same task in the 8048. The 8048 is paricularly bad at some things, especially subtraction and indexing (since it doesn't have these features at all) and has very few addressing modes. It can still do the job, but in a weird, round-about sort of way. This is probably why the 8048 was used in exactly one video game system, and found its niche not as the main CPU in home computers, but as their keyboard encoders.

[doug0909]

Thanks so much, I have a far better understanding of the two systems' basic capablilities and limitations now. Yes, Kirin does sound a bit insane, but I hope that, like Van Gogh, he channels his insanity into some great art. Like, say, kick ass O2 homebrews. Kill the Attacking Aliens, Mr. Roboto, and others prove that even with a limited playfield and limited custom sprites, there's still some flicker-free goodness to be created out there. Or maybe Kirin can fix that damn Looney Balloon rom.

 

And if anyone wants to go "the other way" and port some of the O2 greats over to the 2600, more advanced systems, or the PC, please let this O2 fanboy be your tester...

Edited May 13, 2006 by doug0909

[ZylonBane]

batari and supercat should both register at Wikipedia and beef up the Odyssey 2 entry over there. The current article is woefully lacking in technical detail.

Edited May 13, 2006 by ZylonBane

[supercat]

batari and supercat should both register at Wikipedia and beef up the Odyssey 2 entry over there. The current article is woefully lacking in technical detail.

 

The Wiki page contains a link to the page from which I got nearly all of my information about the O2, so I couldn't really add much.

[NovaXpress]

E3 must have stoked everyone's fanboy instincrs. I strongly feel that the O2 is underappreciated and was never recognized by the American masses for being the fun machine that it is. But it doesn't come close to being technically equal or superior to the 2600. That's just an embarassing argument to make.

 

Forgetting the software for a moment, how about giving the O2 some appreciation for the Master Strategy Series. They were the ones clever enough to think of this concept first and back in the day, only the O2 offered the video/board game hybrids. All three in the series are classic games for group play.

[doug0909]

Huh???!

 

I loved the O2, but the board game for Quest for the Rings was just OK (the "Ringmaster" just sat around placing playing pieces, so it was more fun to just kill monsters with one other player) and the board game for Conquest of the World downright SUCKED. Did you ever try to play it? It's painful... And I am one of the few people out there who likes the video game portion of Conquest...

 

The only board game that worked was The Great Wall Street Fortune Hunt, but that was more of an educational title and you just responded to text on the screen...

 

The idea of mixing a board game with a video game was pure genius in an era where the systems could only handle so much, but it wasn't executed very well on the O2... Maybe if the O2 had lived a little longer.... I heard there is an unreleased Master Strategy game called Sherlock Holmes out there, maye it would have been better than the board game portions of Quest or Conquest....

Edited May 14, 2006 by doug0909

[NovaXpress]

Yes, the boards were pretty much just firewood, but it was original and exclusive to the O2. And the games were fun, though come to recall we eventally ditched the boards altogether.

 

Has anyone actually played a full game of Quest for the Rings since 1983?

[doug0909]

I guess my conclusion, from what I've read here and from what I think I understand, is that the O2 is not technologically superior to the 2600. However, it could do some things, particularly games with a large number of big, colorful, flicker free, fast moving sprites - which would be hard or impossible to reproduce on the 2600. At the same time, the O2 just could not produce the number of static sprites (including backgrounds, playfield objects [pacman dots], and custom sprites), or the scrolling screens, in some 2600 games (or the 2 channel sound unless you had a Voice)....

Edited May 14, 2006 by doug0909