BigO

PM sent requesting some 2600 games: Golf Indy 500 Kaboom Megamania River Raid Word Zapper

Just in case someone curious person wanders in here: I forgot I had taken a picture of the cartridge guts. The Flash memory chip is a M5M29GT320VP-80. The other side of the board is nothing but the connector that plugs in to the console.

Commodore 64: Fast Load Cartridge by Epyx UPC 8056100119, if that means anything to anybody. Excellent condition. In box, which is itself in pretty decent condition. No manual (assuming there ever was one). Don't have a system to test it on, but think I know where I can find one if necessary. I'm not up on C-64 pricing and didn't see anything with box on the web in a quickie search, so will have to entertain offers (possibly trade for 2600 games). "You're tired of waiting three minutes for you programs to load." "Transforms your Commodore 64 disk drive from a lumbering hippo into a leaping gazelle." What more could you ask for?

If there isn't a resistor internal to the 2600, then one will be required externally. Not just to protect the TIA, but also to produce proper operation. The goal of the circuit is to charge the cap about 1/200 of the way with each pulse. With no resistor or other current-limiting circuit, the cap would probably charge too quickly. If the circuit is supposed to have similar behavior on the 2600 and 2600A, it may be necessary to use a current-limiter circuit instead of a mere resistor. I'd suggest something like this: . +V . ,-R2-+ . | R1 . | | . | E .PWM--R3--+---B . C----- Paddle The transistor should be a small PNP type (2N3904 or equivalent). As a guess, I would suggest R1=100ohm, R2=1K, and adjust R3 as needed. The PWM should be low to charge and high to not charge. Thanks. Duly noted and now available for my future reference. (Thankfully, I won't have to rely solely on my memory.) Since my circuit will have to have calibration capability anyway to do the centering and physical to screen position correlation, I think that same adjustment should by its nature compensate for the variation in behavior between the two internal resistor scenarios. On that basis, I was thinking a fixed resistor might suffice for protection. The same conventional paddle controllers will work on either 2600 or 2600A so the minimum resistance of the potentiometer itself seems to be sufficient protection for the TIA on the 2600A. I take it "low to charge" means to apply a suitably small resistance between pins 5,7 and/or 5,9 and "high to not charge" means to leave the 5-7 and 5-9 connection open (or highest possible resistance). I believe I'm track. Cool. Now all I have to do is finish my mechanical version, write my first game then acquire the necessary equipment to work on this excuse-to-play-with-microcontrollers project...say, since my wife's ~$13K long-arm quilting machine just arrived yesterday, now might be a judicious time to spend a few bucks on my own hobbies.

GASP! Your poor TIA!!! -Chris The 5 to 7 short was only in reference to the earlier discussion about the circuitry to emulate a paddle controller, not the keyboard controller scenario. I was just saying that if the RIOT supplies 5 volts on pin 4 which is shorted to pin 5 via the * key, that might effectively be the same as shorting 5 to 7 in the earlier discussion. But, I guess you must understand that because you addressed that concern regarding the RIOT's pull up capability. I'm convinced, a current limiting mechanism of some flavor will be in order if I try to emulate the paddle controller signal with active hardware. I believe the TIA has forgiven me for my miswiring episode as it still permits me to play Circus with my standard paddle controller and with my prototype homebrew potentiometer based controller.

Did you find some commented source code? There's a repository of disassemblies, including commented disassemblies, go here and scroll down to "Source Code" for some links: http://www.atariage.com/2600/programming/index.html Michael Thank you for pointing that out. I had found some here and there, but not that whole group.

Never heard of it until today, but I might be able to snag one tomorrow. (Having an employer-supplied phone with unlimited web access is soo cool.) They seem to be a somewhat hacker friendly thing (A web server ???!). http://en.wikipedia.org/wiki/3Com_Audrey I spotted one tonight at a Goodwill near by. It's in its original box, with manual, stylus, power supply, keyboard. I fired it up and it works. Not pristine, but not bad. Didn't test the keyboard, which is missing the battery cover. I'd have picked it up for myself, but most definitely don't need another project right now. I could probably be persuaded to pick it up for someone who's been desperately searching for one. Don't know if the $20 price is good or not. Might cost that much again or more to ship too, I don't know. You'd have to send me a money order to pay for it and cover the shipping costs and wait for me to get paid before I ship and wait for me to get it shipped...in other words be patient with me. Send me a note tonight and I'll try to check back soon enough to hit Goodwill early if someone is interested. If you're in the Phoenix area, I'll just tell you where it is.

He may be busy updating his website as I don't see this item on there yet.

Be careful...not all 2600's have those resistors. Some of the joystick port pins are directly touching the TIA chip.It wouldn't be a bad idea to add a small resistor just to be safe. -Chris Ah, I see in the schematics (AtariAge archives) that the CX-2600 does have the resistors and the CX-2600A does not. Good to know. Of all things in a 2600 that I'd want to let the smoke out of, the TIA would be pretty far down my list. There's no protection on those pins in the TIA hardware? It must be considered nearly impossible then for a potentiometer to actually supply a zero resistance. I note that the Keyboard controller pulls pins 5 and 9 high through 4.7K resistors to pin 7, but shorts 5 or 9 to any one of 1,2,3,4 depending on keypresses. With 5 and 9 both being inputs to the TIA, that would mean that 1,2,3,4 (pa0, 1, 2, 3 of the 6532 RIOT), configured as outputs, are pulsing the rows (or columns, whichever) of the key matrix. Pressing the * key shorts pin 5 to pin 4. Pin 4 is presumably alternating between 0 and 5 volts. So, when pin 4 is high and I press *, would that effectively be the same as shorting pin 5 to pin 7 in the scenario discussed earlier where pin 7 is supplying 5 volts? Or is the RIOT port not quite that assertive? I guess it's all academic, really . . . just trying to bolster my gut-level understanding of this animal. I probably should take any deeper discussion over to a separate topic. (I can say with certainty that my console can withstand a dead short between pins 5 and 7 while playing a paddle game with no ill effects. )

supercat, switching between zero resistance and hi-z was was one of my earliest inclinations but I thought I'd first try zero resistance and max resistance as that more closely modeled the pot (in my mind anyway). I reckon though that switching between a short circuit (minimum charge time on the internal cap) and hi-z (cap never charges) would be more effective. In other words: switching between [charge-as-fast-as-possible] and [charge-not-at-all] vs. switching between [charge-as-fast-as-possible] and [charge-slower-than-as-fast-as-possible] In terms of the discrete component approach, FET? Or just a reg'lar old transistor switching the connection on and off, driven into/out of saturation by a variable frequency input? I'm not much good with analog stuff, but am definitely up for simpler+cheaper=better. In my more digitally inclined mind, I want to think tri-state buffer...alternate between hi-z and 0.

My wife, with considerable experience in both crochet and knitting, says it's definitely all crochet.

Thanks, guys, for the great discussion. Yeah, it makes a lot of sense to me that the PPM type scheme would be better at avoiding timing issues. Good point, supercat, about the two modes of the potentiometer. The Atari paddles use resistance mode. Clearly, they're prone to jitter. I'm always in favor of using the simplest and cheapest possible technology that will get the job done so if pots is it then pots it is. It occured to me to try a cap to clean up the paddle jitters in the standard controller but couldn't work out in my head what effect this would have on the linearity of the control and I've already cleaned all three of my sets anyway.

It occured to me earlier today that one might be able to improve the safety of head to head play with this thing by using an add-on "image splitter" of some sort to allow the camera to pick up both players in the frame while they're separated by, say, 3 or 4 feet, but could both still clearly see the TV screen. Possibly a thin reflective wedge with it's pointy end near to and centered on the lens could provide the same separation, but would reverse the image(s), so I guess that would be unworkable. (Can you tell I don't know a lot about optics?) Might be interesting to see what games could be controlled effectively with a half-screen wide field for each player.

"fixed-pulse-width period modulation": does that mean that the duty cycle within the pulse remains constant, say 50%, and the period of the waveform is increased and decreased? And that would be in contrast to a constant frequency/period waveform with a variable duty cycle? Thanks for the one microsecond estimate. I had no clue where a reasonable starting point would be in tinkering with this. I think we're essentially on the same page, which gives me a whole lot more confidence that such a scheme might actually be workable. To eliminate the jitter issue completely, I would probably need to consider sensing the controller position with an absolute position encoder or an incremental encoder with detection of a "home" position (to keep the system aware of the actual physical position of the controller), whichever is cheaper and/or easier to implement. They're probably becoming more common than potentiometers these days anyway.

Before I get lost in the 2600 coding time sink, I want to say "Thanks" to all of the people who've put in the time to share code samples, tips and tricks and write tutorials for boneheads like me. I wouldn't in a million years have figured out some of that stuff. Know that your time and effort is appreciated.

Oh, most definitely. This is complicated further by the usable range differing from game to game. I think I have a fairly simple method to make the needed adjustments in an electronic implementation. Of course it often seems easy until it comes time to implement. In my mechanical implementation, I can't just slop at the ends of the potentiometer rotation as the device has a restricted range of motion and needs to correlate its absolute orientation to the absolute position of the player on the screen. So, I have to control both the centering and the total travel of the potentiometer. The centering adjustment is done by setting the controller to its physically centered position and centering the player on the screen by rotating the potentiometer housing in its mounting. The overall range of motion is adjusted by adjusting another part of the mechanism which governs how many degrees the potentiometer rotates relative to the user interface of the controller as it moves through its full range of motion. The ratio of motion, (potentiometer:mechanical user interface) ranges from 1:1 to theoretically 0:1. But, I doubt that I'll need to ever even approach that 0:1 for actual game play. The finished design may limit that adjustment so as to prevent the appearance that the device isn't working at all. (On the other hand, allowing that 0:1 position would obviate the need to lock the controller in place for the centering portion of the adjustment.) Because the range of motion of my controller is relatively small, I had to use a higher value potentiometer to match the 1 Megohm delta afforded by the standard ~330 degree paddle controllers.

Yes, the website lists 8 other games and proclaims "Plus more games coming soon!" http://www.toyquest.com/GoGoTV/games/default.htm Interestingly, most if not all of the other games include special equipment for playing each of the games: tennis racket, mallet for whac-a-mole, baseball bat, etc. It appears to still be a living, breathing console system with games available at major retailers (according to the website anyway). Some additional games/accessories can be found at Amazon.com. The console and accessories appear sometimes spelled "go go tv" and sometimes "gogo tv" and sometimes "go-go tv". The logo contains the words Go Go separated ambiguously by a possible space overlaying or overlaid by the word TV. Some ebay'ers refer to it as "TV GoGo". Probably a poor choice in terms of creating a clearly recognizable brand. Even with the additional paraphenalia that goes along with the new games, they seem to be less than $20.00. I find the more physically interactive control mechanism to be the most compelling part of the game play (hence, my tinkering with a "balance board" analog controller for the 2600). That's the thing that makes the Wii the only "modern" game console that I found interesting: it exercises more than kids' thumbs. I see it as a Wee Wii in that regard. One thing I'd say is missing from the GoGo games I've seen is head to head play. I think they might be able to implement that with colored gloves or somesuch. Of course, the proximity of multiple players might lead to similar injuries as those associated with Wii-play. The peripherals with the GoGo games require batteries, so there is presumably some sort of light being transmitted to allow the device to be clearly recognized by the game consoles image processing stuff. That sort of mechanism might also be used to distinquish multiple players if the console has the horsepower. Maybe the horsepower isn't all that limiting if you consider what the early pioneers and probably more so today's homebrewers have done with/to the Atari 2600. Given what (little) I understand about the Wii's architecture, I imagine that it could support a web cam and thus duplicate the interactive, on screen control methodologies of the "GoGo TV". Not that the GoGo unit is setting the market on fire, but it seems like Nintendo could take the GoGo out of the market if they could match the functionality and price point of the games. And, of course, full blown desktop computers and more practically "media center" computers could do this same thing.

The right approach is almost certainly to use a small microcontroller to manage things. This will avoid many of the "jitter" issues that always seem to plague paddles, and also allow good control of centering and range. Non-microcontroller approaches may work, but would most likely be more complicated. Yes, sir, I completely agree. Hence the topic on the other thread where you were assisting me. My current project, however, is designed to be constructed with simple hand tools by someone with basic mechanical skills. I admit it was more of a mental challenge for me to come up with a workable mechanical design.

I prefer the analog joystick model to the digital "Atari" joystick. I was just thinking of this same thing the other day while looking at the array of analog joysticks in a thrift store. If I remember correctly, the typical analog joystick doesn't have a 1 Megohm delta between the min and max resistance as the paddle controllers do. I've found recently while analyzing the paddles for a project of my own that the when the player is in the center of the screen, the paddle controller is nowhere near the center of its travel. On Circus and Breakout and the games don't use anywhere near the full range of rotation of the potentiometer. Basically, the paddle controller doesn't bump against mechanical limits because of the unused slop on either end of the range. The player maxes out long before the controller does. Circus uses about 90 degrees of rotation. The resistance delta is about 270K but is not at all centered around the 500K center of the pot. I can't find my notes now, but the game-used range was skewed quite a bit toward the counter-clockwise travel limit of the pot (I want to say about 70K on the bottom end of the range). Breakout was fairly close to Circus in its usage of the potentiometer, but Casino was way different. I think it required nearly the full 1 Meg/330 degree delta. This effectively requires variable gain and variable centering to implement the full range of on-screen motion across different games. I said all of that because I had hopes of making an analog joystick that could double as a paddle controller (effectively it would be the Player 0 and Player 1 paddles or the player 2 and Player 3 paddles acting together. In designing a different sort of controller, I came up with a way to implement both the variable gain and centering in a fairly simple mechanism. It hadn't occured to me until just now that it might be scaled down to work in a joystick. I have a preliminary design in my head for an electronically more sophisticated unit (I was discussing in another thread) that would make all of the adjustments much simpler to do as you switch between games with differing requirements. That concept would be more easily applied to the joystick model than my mechanical model. If new games made use to the entire range or at least roughly centered the motion, it wouldn't be a big deal to replace the potentiometers in a regular old PC joystick to get the necessary resistance change within the limited range of motion afforded by the joystick form factor. I'm running something like a 7.2 Meg pot in my controller and haven't acheived the full 1 Meg delta in my limited (<60) degrees of rotation. I think I'm maxed at about 500K delta, but it's all still pretty sloppy and in an exploratory, proof of concept stage.

Dunno if it's a bargain or a rip off, but saw this stuff on craigslist in my area while cruising for 2600 stuff: 50 carts for $150 http://phoenix.craigslist.org/clt/284586003.html

You could make this work. If you connect a resistor from the port to the PWM signal. The R/C forms an integrator (low pass filter) which averages the PWM voltage over time. You just need to make sure that the average voltage is above the detector's trip point or it will never trip. The farther above, the shorter the delay. But I think if you're going to go to all this trouble, you might as well just set a timer on the external digital signal and yank the capacitor voltage when the timer expires. This is probably easier both in hardware and software. -Chris Thanks, Chris. (If it seems I was repeating you or ignoring you at all it's just that our replies overlapped.) Between you and supercat, you've given me a clearer picture. I think it would in fact be simpler to follow the more directly timer oriented methodology both of you have suggested. [Edit] Then again, I'm not sure how I'd be able to know when the Atari was going to read and synchronize with that. Now I'm back to the concept of a sufficiently high frequency, variable duration switching to hopefully get the cap charged in a manner similar to what an analog pot would do. If I get around to the project, I'll try these things and post back here with any interesting results.

supercat, thanks for the feedback. "PWM" might be misleading in that I most commonly see it used in the context of power delivery and this is indeed somewhat different. I guess what I'm proposing would amount to some some oddball sort of current limiting. But, I think we're talking about basically the same concept. My plan was to pull pin 9 up to the level supplied by pin 7 (+5v I believe) through a 1 Meg resistor to mimic the potentiometer at its maximum resistance. Speaking here of the Right paddle controller, shorting pin 7 to 9 is equivalent to the potentiometer at minimimum resistance (zero). My reasoning was that I'd use a transistor or analog switch IC (or something) to bypass the 1 Meg resistor (short across it) in a pulsing, PWM'esque manner. I reasoned that this would affect the charge rate of the capacitor by altering the power that is delivered to the capacitor in the same manner that a PWM voltage is to deliver variable effective power to a motor. I have no clue what frequency would be appropriate or if it would even work at all. I figure if I alternate between the min and max resistances at some frequency and a variable duration, I might be able to simulate the presence of a pot. (It's for a more sophisticated version of the purely mechanical controller that I'm tinkering with now.) It strikes me as being similar to an analog tachometer circuit in that the console's internal capacitor converts the pulses to a DC level. But, I figured there might be problems with ripple at certain frequencies so thought a purely variable frequency model might be a bad plan. Have I clarified my proposal at all?

Does anyone happen to know the maximum resolution that the 2600 can read from an analog input such as a paddle controller? I understand generally how the 2600 reads this information: it does an A/D conversion by timing how long the capacitor takes to charge (as determined by the potentiometer setting). I assume the resolution is a property of the number of bits in the counter that times the charge cycle, but not quite sure how to put this information together. It might help if I phrase the question a different way: If, in place of a potentiometer, I were to use a bazillion position rotary switch with a different resistance level attached to each of the positions, how many discrete positions could the 2600 detect? Partly, it's just a general knowledge or academic type question, but I may apply the knowledge to a controller that I'd like to build at some point. On a related note, does anyone have any thoughts about the effectiveness of using a PWM signal to simulate the variable resistance ordinarily presented by the potentiometer in a paddle controller?

I just picked up a "Go Go TV" video game at the local thrift store. I remember seeing it advertised some time back and was interested in the user interface. As it's only obvious game controller mechanism, it uses a video camera built in to the unit to point at the player(s) and react to motion detected in appropriate regions on the screen. http://www.toyquest.com/GoGoTV/index.htm Can't tell much about the "blob on the board" processor in the unit. I took the included "4 in 1" cartridge apart. It's a 4 Megabyte Flash memory chip. http://www.datasheets.org.uk/search.php?q=...&sType=part I don't currently have the equipment to read the Flash memory. In the "Penguin Maze" game, there are "ghosted" triangles at the 4 edges of the screen. Waving your hand (motion) in space such that the motion appears on the screen in one of the triangles causes the player to move in the direction that the triangle is pointing. It would be an interesting, albeit highly challenging project to build a more universal controller that worked this way and could be used with other video games (thinking of the Atari 2600 specifically.) Just curious if anyone around here has any specific technical knowledge of this unit's inner workings or any knowledge of a "universal" controller system that uses the motion detection/video overlay methodologies. Seems unlikely that anyone has ever homebrewed games for this little gizmo.

Sounds great. I'll be following the progress. Go forth and multicart.