BigO
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Posts posted by BigO
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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.
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With analog comes calibration....
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Your 'offset' is going to be different for each machine.
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.
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Was any additional cartridges ever released for this system?
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.
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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 from game to game.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.
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Create an analog joystick for the 2600 that uses the paddles movements for x and y axis'.
This would be great for space shooters.
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.
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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
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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.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?
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.
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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?
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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?
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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.
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Thanks for your kind offer, but I just opened one of my cartridges to verify the measurements I received. If I do a small production run, I'll buy new cartridges from vgawiz though - unless they're charging a ridiculously high prize for them.
I can't promise if there will be some kind of kit - I never intended to do that. I just planned to release the schematics and PCB layout, so everyone can make his/her own cart. Since I'm getting so much positive feedback, I think I'll go further than that ...
Sounds great. I'll be following the progress.
Go forth and multicart.
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I used to feel guilty for cannibalizing these "rare and valuable treasures" (haven't you looked on ebay?). Came here, got over it. Plan to try to make a deal on a recently spotted pile o' Combat carts so I can do my own repros of the rarest of the rare for myself. Will it minimize your guilt if someone else commits cartricide for you? I can go pick up one cart at any time for 50 cents just a short hop from my house. [EDIT]: Though if you're located in deepest, darkest Africa, transportation might be a bit pricey...
C'mon, you know you want one. You don't get to lament people's unwillingess to share information if you can have said information right at your fingertips.
Add me to the list of people who'd be interested in technical specs required to build my own version of your multicart toy. Have thought about it myself, but haven't mustered the interest or energy to that level. Don't speak FPGA yet, but could always use an excuse to learn.
Thanks for sharing. (If you offer a kit or completed unit at a low enough price, I'll be asking to be moved to one of those lists instead.
)... I hope so, it depends on what you need. If you just need some measurements, I can do that. Unfortunately I don't have any CAD or mechanical drawings, though... What are you looking for?
No, I'm not expecting you to do the measurements for me. I just thought you might have already made a Atari 2600 PCB yourself and thus already know the exact dimensions of the board outline such that it fits into a shell. I'd also like to know the position and diameter of the drill hole for the shell screw, but I guess I'll have to figure that out myself, since noone seems to be willing to share this kind of information :-(
So...somebody could just gut a $0.00 - $0.50 Combat cart and send you the empty shell so you can measure for your specs?
Thank for your help! I hoped someone was in posess of a "official" mechanical specification for the cartridge shell and the pcb, but it looks like those documents haven't survived or even did never exist. Since I don't want to cannibalize old cartridges, I'm planning to buy new cartridge shells for my MultiCart. I wonder if the ones from vgwiz and PixelPast are compatible to each other. I somehow doubt that - even old cartridge shells were slightly different to each other, so I'll have to design my pcb to fit one of these in advance.
On a different thread, a user called bah posted his measurements of a Atari 2600 and 7800 pcb - I'm going to use that as a reference.
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... I hope so, it depends on what you need. If you just need some measurements, I can do that. Unfortunately I don't have any CAD or mechanical drawings, though... What are you looking for?
No, I'm not expecting you to do the measurements for me. I just thought you might have already made a Atari 2600 PCB yourself and thus already know the exact dimensions of the board outline such that it fits into a shell. I'd also like to know the position and diameter of the drill hole for the shell screw, but I guess I'll have to figure that out myself, since noone seems to be willing to share this kind of information :-(
So...somebody could just gut a $0.00 - $0.50 Combat cart and send you the empty shell so you can measure for your specs?
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I was going to ask about the end label being destroyed. It's a bit of a tough spot, opening the cartridge to prove its value when in the process some of its value would be destroyed if its legit.
I wonder if the seller knows any surgeons who could use a 'scope to take pictures inside?
[Edit]: I now see that the end label question has been addressed to some degree by the seller. But, it's still on there so would make opening the cart difficult, wouldn't it?
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I'd be interested in:
Flag Capture
Real Sports Football
Space Attack
Towering Inferno
I'm sure my puny collection of duplicates wouldn't be of much interest to you in trade: Asteroids, Battlezone (non-dust cover carts with slots in the shell if that means anything), combat, Carnival, Donkey Kong, Dodger Cars (Sears), Night Driver (Sears), Galaxian, Eggomania, Pole Position.
What methods of payment are accepted and what would shipping charges be? (ZIP 85051)
Forgive my ignorance/blindness, but do I just go that link and somehow make the purchase there?
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While I surely hate that anyone would rip off anyone else, I don't see a problem with making reproductions. Maybe a (relatively recent) date printed on the label would be a strong enough indicator without totally ruining the effect.
I don't see it as being any different from furniture or cars or anything else that is reproduced. There are thieves everywhere you look. I don't intend to let their moral shortcomings change what I enjoy about life. I was happy to find the Atari 2600 community so active in repros and homebrews.
In fact, I think I have at least minimal computer/electronics skills and access to a high end digital press for making labels so have thought about making repros of some cartridges for my personal collection. They'll play just like an original, so they're good enough for me. I may even create a game of my own. Been doing a bit of studying existing source trying to get a feel for it, picked up some vintage 6502 books, downloaded Stella programming reference materials, got my SuperCharger handy and waiting for me to do Colbert's mod... Say, I probably should stop spending so much time reading and writing these posts and get after that programming stuff.
I'm also working on a controller that will let me do a bit of a "core" workout while playing my Atari. Ripped up some surplus electronics today to get at some pieces for the prototype. Can't let the Wii people burn all the calories can we?
Back to the topic at hand: if I were contemplating spending even hundreds, let alone thousands, on an Atari cartridge from eBay, I'd surely do my homework. Obviously, I have internet access if I'm buying on eBay. It couldn't take more than 20 or 30 minutes to find an image of the genuine article online and enough history to realize that it at least *might* be a scam. (Actually, I'd ask someone to just shoot me for contemplating such a thing, but I'd expect normal people to do their homework.)
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I'm also in the market for an EPROM/PIC programmer. The Willem devices certainly looked good enough on "paper".
Though I haven't done any deep research in to the details of this aspect but they seem to be "open" which has some appeal in terms of longevity and allowing me to create support for future chips if necessary.
On the other hand, in the back of my mind waves a tiny red flag emblazoned with "Cheap Junk - Danger!" And, I'm having an awfully difficult time discerning which device is which model and how many different models actually exist.
What problems have any of y'all had with the Willem units?
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"[...] the site looks hmm idk if i can trust it."
Based on a very recent experience (less than a month ago), I say you can most assuredly trust the Hozer Video site. I got my CD with no hassles whatsoever.
It's a rare thing to get more than you pay for these days. I was quite pleasantly suprised by the quality of what I got for the mere pittance of $5.00. I mean the thing comes in a jewel case with professionally printed liner a 32 page soft cover manual, also very nicely printed.
Subtracting out the cost of the mailing envelope, labels, tape and $1.59 postage (and whatever chunk PayPal takes) from the total $5.00 that I paid and accounting for the time it took him to package these things up for mailing, it felt like I took advantage of Randy rather than the reverse. I'm still tempted to send him more money . . . if only I weren't so cheap.
Just cough up the 5 bucks. You'll be happy that you cashed in your empties or dug change out of the couch or your car's ashtray to make the purchase.
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Does there happen to exist a repository of commented (heavily/tutorially/talk to me like I'm 4) source code for some of the classics, e.g. Space Invaders?
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BigO is an old nickname. Bestowed upon me by others. Really, it was.
...okay, so it's not really a sordid story. O is the initial of my last name and I got the nickname long before I ever heard of that other meaning of the term.
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Not a lot of luck with thrift finds here. Best I ever did was a Tomy Tutor with original cassette interface cable and controllers and 3 game carts.
Only once have I found any Atari stuff and that was last night where I picked up 9 relatively common cartridges that I didn't yet have. Up to ~60 in a few months of collecting.
Anybody have recommendations for a good readily available cartridge storage/organizer/display thingie?
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Control scheme idea
in Hardware
Posted
"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.