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FB2 Cartridge-fied with Autodetect


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#26 supercat OFFLINE  

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Posted Sun Aug 14, 2005 10:00 PM

Tried it on an eprom multicart, no voice.  Also noticed that the Galaxian .bin has the same problem as the official cart: screwed up with an extra column of bad guys.  This makes me think my problems are long wires and not the 4.2v VCC.  Time to shorten things up.

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What is the exact behavior of the extra column of bad guys? I would think that if the problem appears with both an EPROM cart and a real cartridge, it's more likely an inaccuracy in the new chip's TIA emulation circuitry. The old TIA probably had some race conditions which may not behave the same way on the new design.

#27 ATARIeric OFFLINE  

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Posted Sun Aug 14, 2005 10:11 PM

maybe make a section for people to show off their work.

Curt


Please do have a section for us to show off!

I cant wait to get my units. 8)

#28 jsoper OFFLINE  

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Posted Mon Aug 15, 2005 11:03 AM

What is the exact behavior of the extra column of bad guys?  I would think that if the problem appears with both an EPROM cart and a real cartridge, it's more likely an inaccuracy in the new chip's TIA emulation circuitry.  The old TIA probably had some race conditions which may not behave the same way on the new design.

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I'm kinda thinking that way now too, a multicart based on a CMOS eprom shouldn't care about a 4.2v VCC and the wires weren't that long. Other people have posted and sent PMs along that line. Here are screenshots of Galaxian and Cosmic Ark, I'm not sure the TIA circuit is all there (still a great product for the price though).

Posted Image


Posted Image

Edited by jsoper, Mon Aug 15, 2005 11:06 AM.


#29 retrocon OFFLINE  

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Posted Mon Aug 15, 2005 12:56 PM

Maybe this was the QA problem that T.J. was alluding to... The TIA recreation just didn't meet his high standards and provide a perfect Thrust experience. Is that it?

Does it support the illegal opcodes? Does it run Thrust on cart? Does it run Video Pinball and Cosmic Ark perfectly?

It would be interesting to make a list of all the games that have flaws of some sort or another.

Note: This is still a great product and I'm picking up a couple when the new batch is released. For $30 this is definitely nitpickville.

Edited by retrocon, Mon Aug 15, 2005 5:08 PM.


#30 DEBRO OFFLINE  

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Posted Mon Aug 15, 2005 1:40 PM

Does it support the illegal opcodes?

Yes, or at least the small set I use. I couldn't run Atari Climber without it ;)

#31 Bruce Tomlin OFFLINE  

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Posted Mon Aug 15, 2005 3:24 PM

I'm kinda thinking that way now too, a multicart based on a CMOS eprom shouldn't care about a 4.2v VCC and the wires weren't that long.  Other people have posted and sent PMs along that line.  Here are screenshots of Galaxian and Cosmic Ark, I'm not sure the TIA circuit is all there (still a great product for the price though).

It looks like the FB2's HMOVE circuit isn't fully bug-compatible with the TIA.

#32 ehenciak OFFLINE  

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Posted Mon Aug 15, 2005 8:59 PM

I'm kinda thinking that way now too, a multicart based on a CMOS eprom shouldn't care about a 4.2v VCC and the wires weren't that long.  Other people have posted and sent PMs along that line.  Here are screenshots of Galaxian and Cosmic Ark, I'm not sure the TIA circuit is all there (still a great product for the price though).

It looks like the FB2's HMOVE circuit isn't fully bug-compatible with the TIA.

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OK....I have worked on TIA myself....not the one in Flashback, but one for the public to use since I wasn't too thrilled with the "public" one being pulled a few years ago. I am in no way complaining about Flashback 2....in fact, I friggin LOVE the machine...for $30 the case and the joysticks are worth that alone! Moreover, I am begging you not to interpret this criticsm or me bashing "competition" ... I am not that petty (except when it comes to that friggin "RetroGames" design...sorry).

My best guess is that there are problems due to the designers using a lot of asynchronous logic and not closing timing properly. In fact, I would bet that they simply copied the schematics without taking a more modern CMOS process into consideration. Moreover, if there is process drift, you'll see strange behavior from chip to chip. You can use a lot of async. logic (by this I mean latches and the like) and get *something* to work...however, if something gets routed differently when building the chip or if temperature changes or if the process changes, you will get a broken circuit. Trust me...one build I had, if certain clear signals were not routed on global routing in FPGAs, you'd get really cool things happening like the lower 40 scanlines of pitfall being skewed and the like...

My FPGA solution seems to be very stable now (actually has been for the past two months)...it was not until I made everything synchronous and spent hours of debugging every little friggin detail in TIA. I kid you not, if you don't get the timing down perfect on every single subcircuit, throw out your design....it will break with one of the 500+ games out there. These programmers exploited evry little nook and cranny of that chip. Moreover, you absolutely need a debugger like Z26 running on the side to verify every single cycle....I cannot see how anyone could develop a chip without paying that much attention to detail. I was a 1/2 cycle off on HMOVE circuitry once that broke Enduro!

So, for a $30 product, buy about 6 Flashbacks...I guarantee you the next one will be even better...this thing will sell a ton regardless. They are going to be awesome Christmas gifts and nobody should think they'll be disappointed with it! Think about what you are getting for the $30....two brand new, quality joysticks, a killer case, and 40 (well in my case 39) games that are pretty much dead on!

However, I don't think you should get your hopes up thinking that you can make portables out of this. I am sure compatibility will be sky high of 75% of the games...however, based on the problems I have seen, I don't think 100% compatibility is a reality.

Finally, please take none of this as bashing of the chip...there were deadlines and schedules to meet...trust me...working for big companies suck.

Ed

PS Yes, I will get my FPGA solution out there...please have patience...and no, I am not going the "pirate your ass of with a USB interface"....but close ;P ! I am hoping the developers will like some of the features I am adding...

PPS As a quick test, try spraying some electronics freeze spray on the new 2600 chip with Galaxian running....I am half tempted to try that with my buggy Secret Quest and Radar Lock....that might fix the problem in the near term for a few frames...

#33 Thomas Jentzsch OFFLINE  

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Posted Tue Aug 16, 2005 1:27 AM

Maybe this was the QA problem that T.J. was alluding to... The TIA recreation just didn't meet his high standards and provide a perfect Thrust experience.  Is that it?

No, I wasn't expecting compatibility problems like that. It didn't even came to my mind then. I just wanted to prevent Thrust being released with some NES-on-a-chip emulation or something like that.

Does it run Thrust on cart?

I would like to know too.

#34 supercat OFFLINE  

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Posted Tue Aug 23, 2005 7:38 PM

I know many carts short pins 12 and 24, but one is 'called' ground and the other is called something like 'shield ground'.  Is it possible that some carts connect one to a metal shield but not the other (for EMI reduction, that would generally FWIU be a good idea).

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Kevin Horton wrote that every cart he had ever checked shorted them together.

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Out of curiosity, did he check the Xonox double-enders? If I were designing one, I'd use one 8K ROM and one inverter chip; the A12 of the ROM would be have a pullup and would be connected to one of the ground pins at one end of the cartridge. Thus, when plugged in one way the pin would be grounded; plugged in the other way, it would float high.

#35 jsoper OFFLINE  

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Posted Tue Aug 23, 2005 8:55 PM

Interesting idea, I don't know if the Xonox guys were that smart though :)
I've tried two double-enders and they both worked except Artillery Duel rolled. The single cart version didn't though which is strange.

I do have doubts about that ground enable scheme though, a lot of my text label games (Sears right?) don't activate, the FB2 menu comes up instead. However they work when I plug them in with a 2600 cart extender I made for my 7800, and that does connect the two ground pins because it's a hacked up Asteroids cart. Keep forgetting to take carts to work or bring home an ohmmeter to check.

#36 A.J. Franzman OFFLINE  

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Posted Tue Aug 23, 2005 9:17 PM

Interesting idea, I don't know if the Xonox guys were that smart though :)
I've tried two double-enders and they both worked except Artillery Duel rolled. The single cart version didn't though which is strange.

I do have doubts about that ground enable scheme though, a lot of my text label games (Sears right?) don't activate, the FB2 menu comes up instead.  However they work when I plug them in with a 2600 cart extender I made for my 7800, and that does connect the two ground pins because it's a hacked up Asteroids cart.  Keep forgetting to take carts to work or bring home an ohmmeter to check.

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Artillery Duel is known to be buggy. I don't know if there is more than one version, but at least one version sold as NTSC makes too many scanlines - in between the correct numbers for NTSC and PAL.

Not all text-label games are Sears. Most or all of the Sears ones:
Say "TELE-GAMES" near the top of the large label
Do NOT have the game name in large text on the large label (it just happens to appear in the variations list on a few games)
Do not say "game program™" near the top of the large label
Say "SEARS, ROEBUCK AND CO." near the bottom of the large label

BTW, did you use a 4016 or a 4066 for your hack? The 4016 has much higher resistance; that could be the cause of the "some cartridges not detected" problem.

Edited by A.J. Franzman, Tue Aug 23, 2005 9:28 PM.


#37 Bruce Tomlin OFFLINE  

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Posted Wed Aug 24, 2005 6:58 AM

Out of curiosity, did he check the Xonox double-enders?  If I were designing one, I'd use one 8K ROM and one inverter chip; the A12 of the ROM would be have a pullup and would be connected to one of the ground pins at one end of the cartridge.  Thus, when plugged in one way the pin would be grounded; plugged in the other way, it would float high.

And that's why you're not designing digital circuits. :-)

It was MUCH cheaper to design a case to take two regular single-ender boards that they already had, not to mention that longer boards would have cost more. (I think I saw the insides of one once, and there's like two inches of empty space between the boards.) It also let them mix and match, which in fact they did.

When you're dealing in large quanitity (or at least hoping to), you have to be aware of what adds cost to a design. I seem to recall that they used glop-tops a lot, too.

#38 Thomas Jentzsch OFFLINE  

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Posted Wed Aug 24, 2005 7:33 AM

..., but at least one version sold as NTSC makes too many scanlines - in between the correct numbers for NTSC and PAL.

Actually it displays too little scanlines (241 instead of 262). That's something many NTSC TVs don't like too.

Edited by Thomas Jentzsch, Wed Aug 24, 2005 7:34 AM.


#39 jsoper OFFLINE  

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Posted Wed Aug 24, 2005 10:45 AM

Thanks for the Artillery Duel tip, and I used 4066s. Some carts DO have the ground pins separated, mainly text label games plus a couple Activision ones. So much for that brilliant scheme. :x

It's funny, testing all these 2600 carts made me realize I don't play them enough. Some of the little known games like Laser Gates and Shooting Gallery were lots of fun.
Too bad Pitfall2, Stargate, Pacman Jr, and HERO don't work at all. But Snake and SW Earthworld are healthy :D

Edited by jsoper, Wed Aug 24, 2005 10:46 AM.


#40 A.J. Franzman OFFLINE  

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Posted Wed Aug 24, 2005 12:27 PM

..., but at least one version sold as NTSC makes too many scanlines - in between the correct numbers for NTSC and PAL.

Actually it displays too little scanlines (241 instead of 262). That's something many NTSC TVs don't like too.

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Thanks for the correction. I calculate that to be 65.2 Hz - almost 10% too fast, not surprising some TVs don't like it!

#41 Curt Vendel OFFLINE  

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Posted Wed Aug 24, 2005 1:17 PM

I'm going to update the site this weekend with some new pic's and more details...

I've gotten a few emails asking for more clarity on the destination point of the wire from the IC2 rom and also I'm going to recommend to those doing the cartridge hack a slightly better way to adding the cart lines to the board which is to use a 1/32 hobbyist drill bit and drill through the pads in the center out of the back of the board, mark each pad # one at a time with a fine point felt tip or fine point sharpy, then feed the cartridge connection wires up through the backside of the board and solder.

Its more work upfront for the drilling, but will make soldering for those not as confident in their soldering skills a little bit easier time and will help reduce bridging/shorting of the pads for those soldering...

This method will also make it easier to reassemble the system back together as well.



Curt

#42 supercat OFFLINE  

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Posted Thu Aug 25, 2005 10:39 PM

And that's why you're not designing digital circuits.  :-)


Uh, I do design digital circuits.

It was MUCH cheaper to design a case to take two regular single-ender boards that they already had, not to mention that longer boards would have cost more.  (I think I saw the insides of one once, and there's like two inches of empty space between the boards.)  It also let them mix and match, which in fact they did.


Well, I forget how much different chips cost when, but the cost difference between two 4Kx8 PROMs and two inverter chips, versus one 8Kx8 PROM, one inverter chip, and one resistor would in at least some years have been sufficient to more than make up for the cost of the extra board area even with double-sided boards.

When you're dealing in large quanitity (or at least hoping to), you have to be aware of what adds cost to a design.  I seem to recall that they used glop-tops a lot, too.

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Atari used die-bonded chips in the later years, and has also used custom silicon in their carts (btw, did all released Asteroids carts include the bank-switching logic in the chip or did earlier ones have external circuitry? If the latter, is there any way to identify the internal design of a cart?). Activision used custom silicon in Pitfall II; I don't know if they used custom bankswitching silicon in their other carts.

Other than Atari and Activision, did any other vendors reach the volumes necessary to justify custom silicon or die bonding?

#43 jsoper OFFLINE  

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Posted Fri Aug 26, 2005 12:53 AM

Ahhh, but the tipoff to that Xonox double-ender design is the fact that CPUWIZ was making conversions a couple years ago.

I thought most of the major 2600 game companies used custom silicon. Most of them had there own bankswitching scheme (Parker Bros, Tigervision, CBS, INTV) usually implemented with the rom and sometimes glop-topped, sometimes not.




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