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Retron77 Compatibility List


godslabrat

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@SIO2

 

"A7" I was referreing to in my post is an I/O pin on the MCU on the retron 77 board (pin "7" of I/O port "A"), not A7 (address line 7) on the Atari cart. Sorry for the confusion.

The pins on the cart that are connected (and that I think the r77 uses to detect the cart) are GND (pin 12) and SGND (pin 24). You might try disconnecting those (by cutting the trace) and put the switch there.
post-10599-0-71834000-1531979661.jpg
The fact that the console detects an unpopulated board seems to indicate that my assumption is correct. As I've said, that's another source of incompatibility that should be taken care of with a software update

Edited by alex_79
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@SIO2

 

"A7" I was referreing to in my post is an I/O pin on the MCU on the retron 77 board (pin "7" of I/O port "A"), not A7 (address line 7) on the Atari cart. Sorry for the confusion.

 

The pins on the cart that are connected (and that I think the r77 uses to detect the cart) are GND (pin 12) and SGND (pin 24). You might try disconnecting those (by cutting the trace) and put the switch there.

 

Thanks. I will try that this evening after work and let you know the results. :)

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@SIO2

 

"A7" I was referreing to in my post is an I/O pin on the MCU on the retron 77 board (pin "7" of I/O port "A"), not A7 (address line 7) on the Atari cart. Sorry for the confusion.

 

The pins on the cart that are connected (and that I think the r77 uses to detect the cart) are GND (pin 12) and SGND (pin 24). You might try disconnecting those (by cutting the trace) and put the switch there.

attachicon.gifatari_cart_board.JPG

The fact that the console detects an unpopulated board seems to indicate that my assumption is correct. As I've said, that's another source of incompatibility that should be taken care of with a software update

 

 

 

So this would be why the older text labels and some homebrews don't even get recognized by the system (screen doesn't even go black)? That is relieving as I thought it was a hardware problem with the cart slot and could never be fixed.

 

post-30305-0-75716300-1532006061_thumb.jpg

 

That is the inside of Slot Machine. I can't understand the minimal of playtesting that went on when original text label games don't work. I do like mine a lot; I'm not loosing sleep over Slot Machine or the other 8 text label carts I have, but it would stink if I went text label whenever possible and found this out. I was guessing it was the missing tooth in the picture. I don't know things. :)

Edited by gorfcadet
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So this would be why the older text labels and some homebrews don't even get recognized by the system (screen doesn't even go black)?

Yes, I think it's likely the cause, altough I can't verify it myself as I haven't a retron 77 (but I might consider buying it if someone manage to make it run Stella 5.x)

 

I was guessing it was the missing tooth in the picture.

The missing pin is unrelated: some of the early games are 2kb in size and therefore they need one less address line than 4k or bigger ones. If you look at the pictures I posted above, the missing pin on your "slot machine" board is address line "A11".

 

The pin on the extreme right on the top of the board and the one at the extreme left on the bottom in the photo you posted, are typically connected together internally and (I believe) the r77 rely on that to detect the cart. Unfortunately there are a few exceptions (including the Harmony/Melody).

post-10599-0-25024000-1532019109.jpg

I checked with a multimeter some of my carts and found one that shows infinite resistance (that is, no connection) on those pins. It's a text label PAL "night driver". Curiously, I have another copy of that game, text label too, that has the pins connected. I don't want to damage the labels, so I havent looked at the boards.

Edited by alex_79
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I guess it depends on how the MCU input pins behave when not connected to anything. If they keep a known state, e.g. HIGH, then it would read $FF for all the addresses when no cart is plugged in.

If the dumper MCU keeps reading the cart frequently, should be able to signal the console when a cart is plugged in or removed.

If the inputs are undefined when unconnected, a workaround is to have the ability to manually select the cart from the menu in those cases when the autodetection using the GND/SGND lines doesn't work.

A mechanical or optical switch in the port to phisically detect the presence of a cart could have been a solution too, but it's too late for that.



Edited by alex_79
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I don't think there's anything else on the cart connector that can be used.
Old clone 2600 consoles with built-in games relied on the GND/SGNG connection too, as well as the official atari "single chip" 2600 Junior (initially designed to have an on-board rom).

Unfortunately that method it's not compatible with all the games.

Edited by alex_79
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So do you think there is a software fix possible to get the 77 to read the carts that it currently doesn't read as there?

 

Maybe tell it to read for a cart whenever it is powered up, regardless if it sees one or not. Then if nothing comes up move on to the menu??

Or make it do something when a certain button is pressed in the rom menu.

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Maybe tell it to read for a cart whenever it is powered up, regardless if it sees one or not. Then if nothing comes up move on to the menu??

Or make it do something when a certain button is pressed in the rom menu.

Either of those sound like good ideas. I think the menu only loads bins right now though I did rename an .a26 to .bin and Stella loaded it fine. I wonder if it is possible to pass instructions to Stella the same way you load a rom. Kind of like executing a batch file or a script. Might be useful for other things as well.

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I don't think there's anything else on the cart connector that can be used.

Old clone 2600 consoles with built-in games relied on the GND/SGNG connection too, as well as the official atari "single chip" 2600 Junior (initially designed to have an on-board rom).

Unfortunately that method it's not compatible with all the games.

Maybe two or more methods combined would work?

 

Just trying to read from cart permanently might require some additional logic.

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Either of those sound like good ideas. I think the menu only loads bins right now though I did rename an .a26 to .bin and Stella loaded it fine. I wonder if it is possible to pass instructions to Stella the same way you load a rom. Kind of like executing a batch file or a script. Might be useful for other things as well.

 

This really seems like an artificial restriction in the menu code. Stella will accept files with any extension (even though its ROM launcher will filter out certain names). But when passing a ROM on the commandline to it (which essentially is what the R77 menu code is doing), any filename would work. Even ZIP files would work. But if you name something other than '.bin', then the menu seems to filter it out. This should probably be fixed.

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Maybe two or more methods combined would work?

 

Just trying to read from cart permanently might require some additional logic.

The SGND method currently implemented can still be used, because if that pin is LOW there surely is a cart in the slot, and in that case you could avoid reading it continuosly, but when it's HIGH, you can't know if a cart without the internal connection is in the slot.

 

In that case I can't think of any other way to reliably detect a cartridge other than actually trying to read it. (That's what the 7800 bios does too).

 

The way I imagine it to work is something like this (keep in mind I only have a very general understanding on how this device works):

 

the dumper MCU must store a flag to remember what state was the slot on previous reading (cartrige plugged or not)

 

 

1 wait some time (e.g. 1 second)

 

2 start reading the cart

(in this stage there's no heuristic to detect the bankswitch, no saving of the data, no sending anything to the main r77 cpu. Just go on until something different from $FF is read or you reach the end of the 4k address space.)

 

3 - if data != $ff is read before the end of cart address space -> cart is detected -> check the cart state flag

{

- if the cart wasn't present before, then

{

- save the new flag

- start the code with heuristic to detect the bankswitch

- signal the r77 that a cart has been plugged

- dump the rom and send it to the r77

}

- goto 1

}

 

- if end of cart space is reached with all data == $ff -> cart not present -> check the flag

{

- if the cart was present before

{

- save the new flag

- signal the r77 that the cart has been removed

}

- goto 1

}

 

 

 

Edited by alex_79
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attachicon.gifIMG_20180719_162606.jpg

 

The reset cart works. I inserted a 330 ohm resistor in line with the button. Probably didn't need that but it worked out nice.

 

attachicon.gifIMG_20180719_164644.jpg

THis is very similar to the detection methods used by the REtron5 and REtrofreak. I had a variety of Famicom carts (and a few Genesis ones) that were not recognised by the Retron. Some of the Famicom games I would fashion a pass through connector out of a 60-72 pin connector piggybacked on a 72-60 pin connector. Sure enough, the Retrofreak detected the presense of the games that previously did not work because the adapters bridged the separate grounding pins. One fun thing to do was remove the NES cart from the Famicom adapter and continue playing my game as long as the adapter remained in the slot.

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This really seems like an artificial restriction in the menu code. Stella will accept files with any extension (even though its ROM launcher will filter out certain names). But when passing a ROM on the commandline to it (which essentially is what the R77 menu code is doing), any filename would work. Even ZIP files would work. But if you name something other than '.bin', then the menu seems to filter it out. This should probably be fixed.

If you have Hyperkin's ear you should suggest that. Also, ability to use folders would be nice.

 

I can't imagine they have time to read all the stuff we are posting in here. Also, Retron 77 is probably not their only project. So, I just wonder if you or someone is helping them filter and focus.

Edited by SIO2
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Can't really say I 'have their ear'. I am not a customer after all (my system was donated). I think perhaps they are more willing to listen to paying customers, either current or potential.

 

What I would suggest though is that they release their menu code under the GPL or some other permissive license, so end users can make changes and re-distribute them.

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Can't really say I 'have their ear'. I am not a customer after all (my system was donated). I think perhaps they are more willing to listen to paying customers, either current or potential.

 

What I would suggest though is that they release their menu code under the GPL or some other permissive license, so end users can make changes and re-distribute them.

That is a good idea. BTW, I am glad you have a Retron 77. :) Everyone should but especially you as maintainer of Stella.

Edited by SIO2
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I have a number of entries I would like to add to the list, if you can grant me access great if not I will list them here.

 

Thanks

https://docs.google.com/spreadsheets/d/1lzJdxHuRL9I-EdJ0f1abb2a9Gv46qLj-gmAj-PSBbN0/edit#gid=0

 

request access via the link and i'll add you, (goes for anyone that wants to edit and update).

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