7800 myths shattered....

[+-^CrossBow^-]

Okay this post is simply to inform and is in no way to offend anybody. But I have had some time recently to test out another 7800 model which from the board part numbers indicates it is a Rev B -002 board which was made in Aug of 88 (3088 stamped on back).

 

What I have found may surprise, not surprise, put to rest, reassure, and also possilbe devalue our 84 models we have been holding so dear.

 

I have been debating to post this for a while due to the vary ramifications which may arise from it. I hope I can be proven wrong but I feel that my findings will be confirmed in the long run.

 

There has long be a debate over the compatibility of the various 7800 models which were made over the course of its short lifespan. It has always been assumed that the only real true 100% compatible 7800 was the original 84 Rev A -001 models made in the July-Oct 1984 timeframe. These models are easily itentified by thier exposed expansion port on the left side of the console. Also internally they feature sockets on which all the ICs are plugged into.

 

We know there are at least two other models. Of those two models there appears to be only actual physical difference. That difference is the lack of the expansion port actually being placed on the main PCB of the 7800.

 

so to clarify we have 3 models known to exist:

 

84 model - exposes expansion port and manufacture dates show an 84 make date. Also they have all the main ICs in sockets instead of being soldered directly to the main PCB. Their board part number will end with a -001 and have a Revision stamp of "A" on them.

 

86 - ? models - have the expansion port installed but show manufacture dates of 86. all the ICs are now soldered directly to the main board and no sockets exist save for one which is on the 6502 proc itself I believe.

Show board part number ending in -002 and a Revision code of "B".

 

88-? models - same as the previous models in every respect except that they do not have the expansion port installed and instead just have a silkcreen layout of where it would have been placed. Again they only have just the 6502 in a socket and all other ICs are soldered directly to the main board. Their main board part numbers also end with a -002 and are listed with a Revision code of "B" as well.

 

Now this is all very boring and why the heck am I bringing this up? Well now for some shockers...

 

Curt Vendel told us in another posting on this board and also has it listed on his page that only the true 84 boards have the initials DJS in the traces on the backside of the 7800 mainboard. This isn't truth. I have seen these initials on every 7800 board I have heard or seen. Even the Aug 88 board I have with the Rev "B" on it..and no expansion port has the DJS initials in the traces on the backside.

 

Also stated was that some Activision Carts would not function on the later model 7800 unless they were the blue label or later Re-releases of the Activision carts. These games are Shuttle, Decathalon, and Robot Tank to name the main culprits. This too isn't true since again the Aug 88 board I have seems to play all of these just fine. And yes my Robot Tank is an old mottled 83 picture label release.

 

What I am trying to say is this guys. Compatibility isn't the issue with these 7800s. I have also studied and examined the mainboard between my original 84 and this newer 88 boards. All the traces are the same and all the components are the same and in the same numbers quantity wise.

 

It is therefore my belief that all 7800s should have 100% compatibility and the reason for the different results before on the other tested units in the past is because of another issue that 7800s suffer that none of the other Atari Consoles really seem to have. The contacts on the 7800 do wear out...and badly I might add. Also Activision PCBs are noticably thinner than those made by Atari. I think the lines...blue screens...and lockups were due to tested 7800s with dirty contacts or contacts not making good contact with the Activision carts since their PCBs are thinner.

 

I know stickers were placed on many early remaining Activision games stating not for use on the 7800. But I haven't had any probs with these titles on either 7800 I have. I simply think that the issue with the contacts was never thought of or checked into in any depth.

 

I hope I can be proved wrong on this as this basically will devalue all the original 84 model 7800s out there. My intention in this testing was only to lay to rest these compatibility issues so that nobody would feel they had an inferior 7800 over another.

 

The only test still left that I cannot test myself...but would. Is the almight Supercharger test. I is believed that only the true 84 models can use the supercharger without damage to it or the 7800. All others have reported problems. I don't see how this could be since all the traces are the same and the coponents are the same as well. The only difference I noticed on the two is that the 6502 and the TIA chips were from different manufactures. This could have something to do with it but I suspect not.

 

Only other differences in the models is that the 84 models have the board part number and manufacture date in the same corner as the fuji logo and Atari Inc. 84 copyright. The later models scattered this info around on the back of the board. For instance the board part number is almost directly under the cart connector on the back solder side. The Manufacture date stamp is off to the right of that in small numbers in a small block seperate from the others. The fuji logo is still there...but it is much larger in size and both 88 boards I have seen still said copyright 1984 Atari Inc. on them. Even though they were made in 88 and by then Atari Inc. didn't exist and was actually Atari Corp. I have heard that there are some 7800s with the Atari Corp. listed on their backsides and that these are the real compatibility culprits. Until I have one of these models myself. I say that all the 7800s are compatible and should pose no problems for use. If you have a cart that locks up or displays bars...then you either have a dirty cart or the contacts in the 7800 cart connector are dirty or bent back too far away from use. Either of these is repairable and should bring to life the cart you are having probs with.

 

I invite all inquires and flames on this. I know this will generate some but it isn't my full intention to do so. I simply felt that this issue was getting out of hand and that it needed to be really investigated further.

[cschell]

There are other differences. Many of the 7800's are lacking a logic chip on the right side of the board, and in it's place is a resistor jumper. I have also opened 7800s that had no sockets at all. I have not tried replacing this chip to see if it fixed things. (I believe that there was another change somewhere else when this chip was removed - but it's all hazy now.)

 

As for compatibility, I have one that will not run the Supercharger or the Cuttle Cart. It's not a connector port problem, although I do agree with you that many of the 7800 problems are caused by that. I recently had to replace the connector port on a 7800 in order to get it to reliably run Pitfall 2.

 

I have one of the end of line 7800's, with no expansion port, and it runs everything with no problems, so it's not just the 84 models.

 

I thought perhaps it could be the different 6502 that was causing the problems as well, as the one 7800 I have that doesn't work with the Supercharger has a CPU from Mexico, all the ones that work don't. But I know of someone with a 7800 that works with everything with the Mexican CPU. I'd like to hear from more people with 7800s on what CPU they have and whether or not it's compatible, as well as whether or not the logic chip is present or not.

 

The reason I suspect the CPU is because of how the FE games (Decathlon, Robot Tank) and Supercharger work. They are the only carts that use a state machine triggered by specific sequences in the address bus states. If the CPU had a different stepping, it could alter the order of the address bus changes, and possibly break these state machines. I know that newer 6502s do have a different order of executing certain instructions, and some of the really new ones even have different cycle counts. I don't think the cycle counts have changed, as that would break the display of several games, but it's definitely possible the execution order changed.

 

I've traced the circuit on a 7800 and compared it to the schematic available from Best Electronics, there are differences although I don't recall what they were. I have not traced the schematic on a non-compatible model to see if it's different, and have no intention of doing so.

 

So I guess in closing, I know that there are 7800s that don't work with the Supercharger, and that it's not a connector issue. I don't know why that is the case though. (It could also be timing related, the 6502s in the 7800 have different transient responses than the older 6507s in the 2600.) I have not had a 7800 damage a supercharger or vice versa. I don't know of anyway they could do that either. I've found both machines to be pretty hardy. I've beat the heck out of a Supercharger and it still works fine. Plugged it into the "bad" 7800, plugged it in backwards, shorted various pins while powered, etc. etc. No damage. I've abused a 7800 as well, and it's still going strong. (Note: I'm a trained professional - Don't try this at home. I'm not responsible for any damage you do while attempting this yourself. )

 

Chad

[SED]

While we are on the subject of compatibility with the 7800, has anyone had trouble with their 7800 High Score Cart. I have the 7800 without port that has the open space for the connector(86'?), and the 7800 with no port or open space (88'). I do not have an 84' version. On the 86' version the cart works great for about 2 to 3 weeks, and then I loose all my scores do to the batterygoing dead. I have the newer HSC cart as well. On the 88' version of the 7800, my scores eventually get all scrambled up. Not sure how long it would keep them though. The 88' version works with the Cuttle cart and Super charger just fine also, and those do not work with the 86' version at all.

 

Just wondering if anyone has had there scores last on the cart for more than a month using a "newer system" besides the 84' version. I have tried leaving it in the system as well as pulling it out after every use, and it only holds the scores for about 2 weeks.

[Tempest]

My Highscore cart doesn't seem to hold scores with my 84 7800. It works just fine until you shut th esytem off and then everything goes away. I have one of the newer versions too. I guess I'll have to ask Curt about it.

 

Tempest

[+-^CrossBow^-]

I do not have a High Score cart although it is one of my wants on my "Want list".

 

As for the CPU thing...I believe the CPU on my 84 model is a AMI or some other but not from Mexico. The 88 model I tested Robot Tank on did have the Made in Mexico on its CPU, however.

 

So without a Cuttle Cart or Supercharger I can't test beyond that. Interesting that the cuttle cart doesn't work on some 7800s either...I thought he had wired around that issue. But sincenobody really knows what that issue is, I guess it can't be wired around. hehe..anyway thanks for the input all the same.

[cschell]

quote:

---

Interesting that the cuttle cart doesn't work on some 7800s either...I thought he had wired around that issue. But since nobody really knows what that issue is, I guess it can't be wired around. hehe..anyway thanks for the input all the same.

---

 

Exactly. I was unable to determine what was wrong, so I couldn't fix it. It's probably a timing problem, possibly in the deglitching setups. The Cuttle Cart works a little better in my "bad" 7800 than my Supercharger does, but is still broken. The original Supercharger won't even load a game, whereas the Cuttle Cart will load a game, but most of the Supercharger games play incorrectly. (Non-supercharger games will sometimes load and play fine though.)

 

Chad

[Eckhard Stolberg]

But you are forgetting the Atari Corp. board number C300633-001 Rev C from 1989. This is the board that can be equipped for NTSC as well as PAL. Therefore all PAL 7800s are using this board. It is certainly incompatible with the Activision games. I wrote a little experimental routine for my cartridge reader based on this board, that allows me to read Decathlon, Robot Tank and Space Shuttle with it. The resulting binaries work fine on the emulators, but I still can't get the games to play normally in the 7800. Therefore I'm pretty sure that there must be a bigger problem than just worn out contacts.

 

 

Ciao, Eckhard Stolberg

[ubersaurus]

My 7800 still doesn't run Kool Aid Man correctly, though it works fine on my 2600.

[Trebor]

How's this for a twist (Although it could possibly agree with Tempest's theroy of connectors wearing thin)...

 

Atari 7800 system where Ballblazer locks up and Food Fight freezes on the opening screen. Additionally, on this same console, Jr. Pac-man for the 2600, the colors are wrong. I believe (*not 100%*) this models is one where there expansion port is 'etched' into the case, but there is no hole, and the expansion port is completly vacant from the board.

 

I have another 7800 which is one of the original 84 models - no problems with everything I have (Although I don't have Robot Tank or Decathalon to test with).

 

-Trebor

[Trebor]

"How's this for a twist (Although it could possibly agree with Tempest's theroy of connectors wearing thin)..."

 

Sorry, meant **Crosbow's** theory.

 

-Trebor

[+-^CrossBow^-]

Colors being screwy are usually a problem with the chromo or luma pot adjustment for the 2600 side. However, if the colors are only hosed up for just Jr. Pac...then it could be a problem with the contacts. Although I usually just get lockups, intermitten drop out of the game to the wonderful multi color bars or simply a black screen upon power up.

 

As for the BallBlazer and Food Fight locking up...I do think that is a problem with dirty or bent out contacts. Actual 7800 games should work just fine on any model 7800 regardless of make.

[atari70s]

Hey Crossbow. heres something im not sure you added. i got a 1987 7800 ( soon to sell ) where it has the external port on cut away so you can use it . you were talking about how the 1988's like you have cover this up. What would the understanding be Since this is a REV A i think . yet dated in xx87 (dont remember teh week)

[KAZ]

Let me get this straight....

 

You are saying that because certain models "seemed" to have better compatibility with Atari 2600 they would be considered to have MORE VALUE...

 

And you are attempting to disprove this, and you think that people would then think their Atari 7800 has a lesser value?

 

Well I don't know about anyone else, but from a collector standpoint, it makes no difference.

 

I wouldn't get a 7800 based on its % capability with Atari 2600 games anyways.

 

As a collector I might want the first version of the 7800, and perhaps the very last version. Or maybe all the versions (if I felt like being obsessive about it, which I'm not). So then I could "show" someone that a game works on one but not the other, and explain why. For those that may collect only one, maybe it makes a TINY TINY difference.

 

And then there are still others who, in an attempt to "disprove" your theory, would actually purchase a 7800 that has less than 100% compatibility, and try to mess with them to try to get games that are said not to work on them, working.

 

From a gamers perspective, maybe all this does make SOME difference, but not much right? So you can play 400 2600 games instead of 415, so what?

 

I'd say to that gamer, get off your bum and hook up the Atari 2600 if you want to play that game so bad.

 

I want to collect an Atari 2600 Heavy Sixer, but there are problems with cartridges fitting too tightly. But I don't care, because I want to have "1 out of 100,000" of that version of Atari 2600, for collector purposes (I have a black version, but want a wooden one).

 

I like playing Atari games, I wouldn't collect if I didn't like playing them (occasionally, when I'm in the mood), but I more like collecting (like a classic gaming anthropologist, seeing what systems were like in the past).

 

Sorry this is becoming long, but I saw an Odyssey 2 live in person at The Midwest Classic on Saturday, and it was BEAUTIFUL. It was so cool looking, that I almost think I want to collect it someday. It had some sort of voice attachment, which made it even cooler!! I'm sure the games are really primitive, but if I were looking for graphics and stuff, I'd get a modern system.

 

[ 06-10-2002: Message edited by: KAZ ]

[+-^CrossBow^-]

Damn...Who brought this thread back from the dead?

 

Okay..first off I only really had 2 different model 7800s I could test with at the time. The 88 model had all the signs of being a non robot tank, Decathalon, Shuttle compatible 7800.

 

You stated what was the point of my post..it was this. Many times on Ebay 7800s will go for way more if they are thought or proven to be one of the 84 made models. These models from initial testing by me and others...seem to be the only 7800s fully compatible with everything for the 2600. From a gaming standpoint this doesn't mean much since your right..most will break out the VCS to play those few incompatible games. But it was rumored that only about 5000 84 models were ever made. So naturally if that is/were true then those units would be in very high demand for their history etc...

 

Main reason is that the true 84 units are Pre Tramiel..and hence mark the last home gaming console made under the Warner Inc. ownership.

 

I am fairly certain now that my 7800 with it's 2584 WWYY stamp on the bottom is an actual 84 model board made in July of 84. However, either it was never put into a case shell during assembly or it was a defective unit that was later reworked and sent back out as new. Point is that my 7800 has 100% compatibility...heck I just dumped and confirmed the existence of an FE bankswitched Shuttle with it...and it plays it I might add.

 

This post is old and much information has been discovered about the incompatiblity issue. For instance the extra circuit that Mr. Schell found was also were the incompatibilty was found. He discovered that clipping one of the points off a Capacitor in this circuit would shut that circuit off. Upon doing that...shuttle and the other game...and the supercharger and Cuttle carts were working again.

 

But then I believe Eckhard discovered that the reason for the circuit is actually because the older 7800s are now incompatible with some later 2600 releases..like Dark Chambers and Secret Quest. Ironic when you think about it...

 

However, in all fairness I do see KAZ's point as well. An 84 model 7800 is valuable regardless of the compatibility it contains simply because it is an 84 model and has that aura of Mystique to it...

[Curt Vendel]

Hmmmmm DJS is on ALL of the MB's??????? Hmmmm, now I must crack open a few of my later units including 2 PAL's I have to see too.... It was my understanding that later rev's were not just minor mod's of the orig PCB layout, but hey.... we all learn something new each day.... Crossbow, don't feel bad cause your bringing new and important info to light.... this is why these forums are so great, we all get to put in info we learn about the hardware, software and history and in the end, everybody wins dude!!!

 

Interesting......

[Curt Vendel]

Atari 7800 system where Ballblazer locks up and Food Fight freezes on the opening screen.  

-Trebor

 

I have a few Food Fights and for some reason they lock up after a while randomly, I've tried them on an 84 and an 88, same thing..... anyone else have this problem???

 

 

Keith Swayer of GCC was the programmer of 7800 Food Fight.... I wonder if perhaps he may know of any issues or maybe he still has the original code.

 

 

Curt

[+-^CrossBow^-]

I only have one game that has ever given my 7800 fits..and it was a Scrapyard dog. It basically loads up title and I get he screen with the ransom note...but then when it switches to game mode...I get a black screen.

 

Also there is a tune that plays on scrapyard dog when you turn it on..and that tune plays different everytime I turn on my copy. Mine isn't a problem with the 7800..it is a problem with the rom...as I dumped it and it was basically incomplete in that there were blanks in the code where it should have been directing the console for more info for the game...

 

Is it possible there was a batch of badly made games..that escaped out the door to haunt us?

 

And yes Curt...everyone I have talked to...has found the DJS Initials on the trace of their boards. That 88 model I had also had them there...

 

So for now...it is a cool hardware easter egg!!!

 

[Curt Vendel]

Hey, its possible.... I bought them all in the same batch from O'Shea's a few years back, I bought 6 each of them when they were dirt cheap, so its possible that there could've been a bad batch, I'm just curious to see if anyone else has had Food Fight lock ups.

 

 

 

Curt

[Joey Kay]

I have never had a Food Fight lockup on my 7800, and believe me, I've put a lot of miles on that cart (it was the second cart I got for my 7800 after PPII back in 1989)

 

However, I have had Pole Position II lock up more than once (maybe 15 or 20 crashes in the last 13 years), and Desert Falcon seems to crash on me enough to be memorable...

 

Cheers!

 

Joey

[Agent X]

I've never had any problems with Food Fight locking up.

[geosteve]

The 7800 I bought back in '86/87 never had any mentionable lock-up trouble, that's with over twenty 7800 carts I owned

 

(past tense - owned - I gave the whole thing to my kid sister and she eventually sold it, but I kept a few carts and did buy another 7800)

 

all the pics on my site are genuine screenshots from my original, I had the thing hooked up to a VCR and copied hours of geniune 7800 gameplay.

here's a link...

http://www.geocities.com/geosteve_99/vgc/p...em/a7800_1.html

 

I did this page back in 98/99 at webjump.com, a free site, that went out-of-business. Every screen had links to more screenshots but not any more, sorry about bad links. Recently I moved it to geocities but had to make a lot of cuts, out of memory space. Hope to fix it soon

[holygrailvideogames.com]

I am just wanted to know if anyone was able to get Sean Kelly's 2600 multicart (new version) to work on their 7800 system. It won't work on my 7800, but works great on the 2600.

[Goochman]

Sean indicates on his page that the 2600 multi cart wont work on 7800 systems.