Atari 2600 Tarzan released!

[SmakyTaky]

indeed...only difference is this pin which is A13... thus enabling 16K access... I did not dump the Mr. Do EPROM... it might very well they just have the 8K image dupped. so it should work on a 16K board even if the A13 pin floats as the data would be the same regardless of the value of this address l8ne.

 

I am wondering.... do you have any other cart with a 91399 board?

[Supergun]

Yes, that’s exactly what I was thinking myself. And so I’m going to be checking them now.

 

 

So far I have found these:

 

 

[Ballblaɀer]

Photos of the board taken from the top, in case they’re still needed…

 

Let me know if more close-up detail is required.

 

 

[SmakyTaky]

I really appreciate you taking the time to go and take them, these photos helped me munderstand a bit more of those connections that were not visible on the bottom-up photos. With them, I was able to figure out a few additional nets -i.e. the cap/R nets. And confirm a few connections on U3 (74LS133).

 

Going down this path and before resorting to the multimeter (which we will eventually need to)... would it be possible to remove the EPROM and 74LS133 from their sockets and take photos of what goes on beneath them? (Again photos from top-down and bottom up help sort out the nature of the connections).

 

[SmakyTaky]

On 6/20/2024 at 7:25 AM, Supergun said:

... And so I’m going to be checking them now.

Did you find any cart with the 91399 board? What games would come with it? I am thinking of looking for one myself to play around and test.

[Ballblaɀer]

Chips removed — more photos.

[Supergun]

6 hours ago, SmakyTaky said:

Did you find any cart with the 91399 board? What games would come with it? I am thinking of looking for one myself to play around and test.

I still have not found a cart with that board. In reality, none of the released 2600 Coleco games should have used it and they certainly didn’t need it. I think the one cart he found with it was an anomaly. Perhaps it was simply a factory mistake. Here’s what I do know:

 

The 91204 and 91205 boards use these 4 IC’s: 74LS02, 74LS04, 74LS11, 74LS30

 

While the 91399 board uses these 4 IC’s: 74LS02, 74LS74, 74LS123, 74LS133

 

So only 1 of the 4 chips is the same on both boards. The other 3 are different chips (2 of them with more pins even) so they work very differently with the data on a larger (16kb) 27128 eprom chip. And while it is highly possible (though as of yet unconfirmed) that a smaller (8kb) 2764 eprom chip could also work on the 91399 board, the reverse would almost certainly not be true. (although again, as of yet unconfirmed)

 

EDIT: I believe the reason that the owners other board “doesnt work” with the Tarzan eprom is because it was mismatched in the past. It may very well work 100%, but only with a proper 2764 EPROM installed.

Edited June 22 by Supergun

[SmakyTaky]

Among other things, the 74LS30 and 74LS133 are both NAND gates... where the later has more inputs compared to the other. These are used to combine several adress lines as part of the banking logic. I have reverse enginered the 91205 board... and schematic and when I manage to complete the 91399 I will be able to tell the differences. It seems the 9133 is using the NAND gate in a similar fashion but using more address lines. The photos provided by Ballblazer will help narrow the schematic for the 91399 even more.

[maiki]

The sound in this game is fantastic. I can hardly believe they are just using 2 TIA channels.

[SmakyTaky]

On 6/22/2024 at 1:21 PM, Ballblaɀer said:

Chips removed — more photos.

Thank you so much... these are very helpful. I was able to identify a few nets behind the EPROM and 74LS133 ICs... 

   

At this point, the photos were able to reveal quite a bit about the circuit. However, the remaining connections cannot (at least, I couldn't) be infered from the photos alone and the multimeter may be the only way to complete the schematic. There are a few connections on the top row of the EPROM that I was not able to figure out... a few more under 74LS133 and ingeneral on the top side of the PCB for the other ICs.

Edited June 23 by SmakyTaky

[SmakyTaky]

I got a parcial success on reproducing the board. I just got the package with the 91205 Rev B reproductions boards from JLCPCB delivered yesterday. I assembled the board using the original ICs I've got from the Broken Mr. Do cart I used as the basis to reverse engineer the board and burned a 2764 EPROM with Mr. Do image to it... this cart worked like a charm... booting my 2600 Jr. to Mr. Do right away. 

 

This means the reproduced board worked fine, and booted the 8K image without issues using mapping logic implemented from the ICs on the board.

 

     

 

So, next step was to burn Tarzan's unmodified ROM image to a 27128 EPROM an tested again... unfortunately, as with the original boards, I was unable to get the ROM to boot on my 2600 Jr. Which after thinking it for a bit, in lieu of this board design, makes sense. This board has Pin 26 of the EPROM tied to VCC, which would end up pointing to the upper half of the 16K image in the 27128 EPROM. Of course, the booting part would never be read and the console would not be able to boot properly.

 

So this probably explains why the EPROM with the Tarzan image would not work on the 91205 board while it works properly on the 91399. I knew it was a long shot.. but the results... although not what I wanted, are expected. On the 91339 board, pin 26 is actually going somewhere to the mapping logic implemented by the ICs... which makes sense as the 16K should be mapped to allow for the image to be read and run the game.

 

So bacl to the 91399 board... I have been struck... as without the board to being able to sort out the missing nets... I cannot finish the schematic for it.

[SmakyTaky]

On 6/4/2024 at 6:09 AM, Thomas Jentzsch said:

Hotspots are $fff0, $fff1, $fff8, $fff9

Is there any place with documentation about about this particular bank switching scheme, how it works and how it differs from F6? I think understanding the bankswitching logic may help me continue reverse-engineering the recreated PCB schematics I am working on to reproduce this cart.

[+wavemotion]

10 hours ago, SmakyTaky said:

Is there any place with documentation about about this particular bank switching scheme, how it works and how it differs from F6? 

F6 hotspots (read or write access) are $fff6 (bank 0), $fff7 (bank 1), $fff8 (bank 2), $fff9 (bank 3)

JANE hotspots (read or write access) are $fff0 (bank 0), $fff1 (bank 1), $fff8 (bank 2), $fff9 (bank 3)

 

It's "documented" in Stella and sundry other emulators that have recently included the unusual banking scheme.

 

[SmakyTaky]

6 hours ago, wavemotion said:

F6 hotspots (read or write access) are $fff6 (bank 0), $fff7 (bank 1), $fff8 (bank 2), $fff9 (bank 3)

JANE hotspots (read or write access) are $fff0 (bank 0), $fff1 (bank 1), $fff8 (bank 2), $fff9 (bank 3)

Thank you , with this information and a bit of research on programing GALs... I was able to modify the F6 PLD Code for 20V8 and 22V10 (based on the code from Pixel Past). Programmed the GAL and A 27128 EPROM with the original ROM from the article and got it to work on my Atari 2600 Jr.

 

So I am a bit closer to this. At least I know the Original ROM I burned works with the JANE logic wich I need to replicate on the 91399 board I am working on.

[4ever2600]

Oh cmon really? Tarzan, Jane?? 🤣  Love it!

Edited July 21 by 4ever2600

[SmakyTaky]

I managed to finlalize the first prototype of the recreated 91399 board. Thanks for the invaluable help of Ballblaɀer probing the missing traces I was unable to identfy from the photos. The schematic is now complete and the gerbers are ready to be sent to JLCPCB for fabrication. Once I get them.. I'll post my findings!

Thank you again  Ballblaɀer!

Edited July 27 by SmakyTaky

[Supergun]

Thanks for not giving up. I myself had thrown in the towel on this one.

 

Once confirmed as functional, if you decide to make a small run, put me down as first in line to buy one.

[+sramirez2008]

33 minutes ago, Supergun said:

Once confirmed as functional, if you decide to make a small run, put me down as first in line to buy one.

I’d like one too, if possible.

[SmakyTaky]

Well... I am not thiking on selling these... I've got 5 prorotype boards for testing purposes. Once I get them test and fix whatever issues I find, I'll probably order a few more (now with gold finish) I have no issue sharing some of them or ordering a few additional boards. Just PM if you like.

 

In any case, let's first wait until the boards prove to be working. In the meantime.. I have repurposed one of my many King Kong carts to use it for the shell.. together with the label I created.

Using the 91205 Rev B boards I previoulsy recreated as part of this journey I was able to have Looping and Cabbage Patch Kids protos working with it. So I am just short on Turbo (which probably will have to live on a GAL PCB) to have the proto COLECO collection recreated.

[Supergun]

I’ve already been there / done that when it comes to that. But I simply used original boards over the years.

(missing Tarzan as it’s too big)

But your sticker quality is certainly much better than mine. I can’t get that glossy look with mine.

[SmakyTaky]

That's only because of the laminated vynil I am using to create them... Cricut machine does it possible.

 

BTW, what board did you use for Turbo? When I had an EPROM with Turbo on the 91205 Rev B board I recreated it would not work properly. I guess the banking logic for it is not the same used on this board so it will boot, show the initial semaphore but when it cycles through it, it reboots. And trying to start the games does that too. so probably it needs a different board. Do you know what board is the one that your cart has?

Edited August 2 by SmakyTaky

[Supergun]

16 hours ago, SmakyTaky said:

BTW, what board did you use for Turbo? When I had an EPROM with Turbo on the 91205 Rev B board I recreated it would not work properly. I guess the banking logic for it is not the same used on this board so it will boot, show the initial semaphore but when it cycles through it, it reboots. And trying to start the games does that too. so probably it needs a different board. Do you know what board is the one that your cart has?

Oh boy, here we go.

(flame proof suit now on)

 

The problem you are having with Turbo is not the board. It’s the rom data you are likely using.

 

There are several different rom builds of Turbo floating around, and their functionality ranges from blank screens, to hang ups, freezes, crashes, etc. It’s the manner in which the banks were compiled together. Most, if not all, were done wrong.

 

However, it only affects real hardware, not emulators, so most people don’t give a care.

 

Theres a thread here where I discuss it. I’ll provide a link to it later for you to read up on it.

[SmakyTaky]

2 hours ago, Supergun said:

Theres a thread here where I discuss it. I’ll provide a link to it later for you to read up on it.

Thank you, I believed this was related to baking.. what was not aware is there were many ROM images with different approaches to it. I will read your post that's for sure.

[SmakyTaky]

9 hours ago, Supergun said:

Oh boy, here we go.

(flame proof suit now on)

 

The problem you are having with Turbo is not the board. It’s the rom data you are likely using.

 

There are several different rom builds of Turbo floating around, and their functionality ranges from blank screens, to hang ups, freezes, crashes, etc. It’s the manner in which the banks were compiled together. Most, if not all, were done wrong.

 

However, it only affects real hardware, not emulators, so most people don’t give a care.

 

Theres a thread here where I discuss it. I’ll provide a link to it later for you to read up on it.

I think I found the thread you are referring to. After reviewing it and testing with different ROMS applying the bank swapping on the ROM images . I would not like to deviate from Tarzan in this thread so I sent you a PM to discuss about it,

[CPUWIZ]

My Coleco PCB is tiny and only uses one additional chip.  Interesting that someone would attempt to re-create the original though.