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Curt Vendel

7800 Expansion Module

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Okay, units are assembled, I'm waiting for delivery of the PLCC socket and DB9 connectors to arrive. New HSC design is done, working on the TTL version of the RAM/Pokey system, then need to look at the secondary audio processor...

post-23-127784365655_thumb.jpg

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Glad to see that this project continues to move forward. Can't wait to hear feedback about the prototypes! Keep up the good work. :)

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Thanks for all the hard work you do for the 7800 community to mr. vendel and all involved. I can't wait!! :lust:

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5. I've solved the interconnect issue with both the proto bus boards and what will go into the final production exp module units to allow them to be mated to a bridge board to plug into the 7800 cartridge slot and extend the slot up through the top of the 7800 exp module case with its own cartridge slot.

 

I've been meaning to ask about the cartridge slot for the expansion module. My question might sound a little silly. So the question is, will that slot be designed to take in every 2600 cart ever made? It would be nice if that module fixes that engineering oversight.

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Can you explain? I planned to use the same 7800 cartridge guide as the 7800's used and the opening with be the same 2600/7800 cartridge size.

 

The 7800 cart ports are actually 36 pin 5200 cartridge ports, which simply have the 4 pins removed.

 

 

Curt

 

5. I've solved the interconnect issue with both the proto bus boards and what will go into the final production exp module units to allow them to be mated to a bridge board to plug into the 7800 cartridge slot and extend the slot up through the top of the 7800 exp module case with its own cartridge slot.

 

I've been meaning to ask about the cartridge slot for the expansion module. My question might sound a little silly. So the question is, will that slot be designed to take in every 2600 cart ever made? It would be nice if that module fixes that engineering oversight.

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It's not the pcb board slot that is the problem with carts not fitting. It's the dust cup that sits around the slot in some later 7800 models that is too tight. That won't be a problem here, as the modified 5200 slots Curt is using don't have the cup around them.

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Yeah, if I recall correctly, Tigervision carts won't fit into the 7800 cartridge slot at all.

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So the later 7800 cartridge guide plastic that goes over the slots are too tight? Wow, never knew that ...

 

I noticed how hard the 7800 carts go in and out when I got my system last year. I only have a few 2600 carts but those plug in easy like I remember in the old days. I initially thought the difference was due to the 7800 carts having more pins and thus more contact area with the connector. But I did some experiments by plugging in boards without the shell, and force levels seemed fine. It does seem that the 7800 carts have a tighter fit with the plastic guide.

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So the later 7800 cartridge guide plastic that goes over the slots are too tight? Wow, never knew that ...

 

Yep, that's why a lot of people will cut one side of the cart guide so some of the 2600 games will fit properly. Imagic games in particular are a problem. The later TigerVision games have a different issue and do not work on any 7800s without modding.

 

Mitch

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Probably something we need to consider in the plastics drawings. Perhaps add a millimeter or two of space

to ensure these other games fit....and hopefully execute.

Edited by Gorf

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Just to be clear, the culprit is not the cart slot opening in the outer shell of the 7800 casing. It's the cup that is attached to the motherboard, sitting around the cart slot that is the problem with the wider carts not fitting.

 

This thing:

 

img_1521.jpg

Edited by Underball

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That is called the Cartridge Guide.

The problem with the cartridge guide is that it is Octagonal in shape, when all the carts are rectangular; and also that it is tapered inward towards the bottom/motherboard.

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Could the 2600 cartridge guide be used?

I believe that both the 7800 and 2600 cartridge guides are made of a single piece of injection molded plastic, and that the 2600 one would need to be modified to allow the extra contacts/pcb width of the 7800 carts.

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Seeing a piece of Atari equipment like the 7800 - with SIO port on it - is very interesting!!!!!

 

Add me to the "impressed" crowd.

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Just adding in the future interfacing to the Pokey chip, it ain't just for sound ya know ;-)

 

What's the SIO port for? It looks that's something for an another add-on.

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Anyone see this on the CoCo3?

 

 

No big deal when you can actually watch 3 movies (and more) at the same time on a MSX (8-bit computer). :)

 

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W-O-W !!! The GUI is great and I can't believe its pulling that much bandwidth across the bus and handling it like that, amazing!!!!

 

 

Anyone see this on the CoCo3?

 

 

No big deal when you can actually watch 3 movies (and more) at the same time on a MSX (8-bit computer). :)

 

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