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Breakout board for N64 Expansion Port.

Cybertronic

Newly Registered


I have been racking my brain on how to build a connector that fits under the N64 for development purposes.

Long story short, I need to be able Connect a Cartridge to the underside of the N64 in order to make use of Expansion Cartridges like the Modem Cartridge or Video Capture Cartridge WITHOUT the 64DD. ie: 64Drive/EverDrive + Modem Cartridge connected at the same time allowing for 64DD cart conversions to use the accessories.

Is that expansion port 100% custom or does something out in the wild happen to fit it? I have looked at 50 pin SCSI cables, I have even looked at the 50 pin telco connectors on phone punch blocks.

At this point I wonder if I am better off just developing a Daughter board with two cartridge ports that sits on the top or a ordering a custom PCB that is the right thickness for the EXT port at the bottom. The ports share the same lines, just mirrored and take turns communicating so It may not be such a bad idea to go that route.

Originally I wanted to make a CF Card Based hardware re-implementation ($$$) of the 64DD that Connects under the N64 and could use the Accessory Cartridges, but then I thought, why not just have a 64Drive or EverDrive talk to them instead? So I could theoretically boot a cartridge from the bottom connector, but that will require custom hardware, or I could put two cartridges up top, which also requires custom hardware, but easier to source parts.

Your feedback is greatly appreciated.
 

josiahgould

Spirited Member


Spitballing here... Could you somehow use a GameShark as a passthrough and access the cartridge attached to the back?
 

abveost

Robust Member

<div class="bbCodeBlock bbCodeQuote" data-author="Cybertronic">

<div class="attribution type">Cybertronic said:

<a class="AttributionLink" href="goto/post?id=988793#post-988793">↑
</div>
<blockquote class="quoteContainer"><div class="quote">I have been racking my brain on how to build a connector that fits under the N64 for development purposes.

Long story short, I need to be able Connect a Cartridge to the underside of the N64 in order to make use of Expansion Cartridges like the Modem Cartridge or Video Capture Cartridge WITHOUT the 64DD. ie: 64Drive/EverDrive + Modem Cartridge connected at the same time allowing for 64DD cart conversions to use the accessories.

Is that expansion port 100% custom or does something out in the wild happen to fit it? I have looked at 50 pin SCSI cables, I have even looked at the 50 pin telco connectors on phone punch blocks.

At this point I wonder if I am better off just developing a Daughter board with two cartridge ports that sits on the top or a ordering a custom PCB that is the right thickness for the EXT port at the bottom. The ports share the same lines, just mirrored and take turns communicating so It may not be such a bad idea to go that route.

Originally I wanted to make a CF Card Based hardware re-implementation ($$$) of the 64DD that Connects under the N64 and could use the Accessory Cartridges, but then I thought, why not just have a 64Drive or EverDrive talk to them instead? So I could theoretically boot a cartridge from the bottom connector, but that will require custom hardware, or I could put two cartridges up top, which also requires custom hardware, but easier to source parts.

Your feedback is greatly appreciated.[/quote]

</div> Whatever you do will require "custom hardware". If you only need one borrow the adapter inside a v64.
 

abveost

Robust Member

<div class="bbCodeBlock bbCodeQuote" data-author="Cybertronic">

<div class="attribution type">Cybertronic said:

<a class="AttributionLink" href="goto/post?id=989688#post-989688">↑
</div>
<blockquote class="quoteContainer"><div class="quote">That would require streaming the 64DD disk rom through the Parallel port on the back of the game-shark while the cart is attached to the top, but that could technically work given the right software, barring any bandwidth or I/O limitations<br/>


Its difficult to track down the adapter that fits between the V64 and the Expansion port. They are almost as rare as the unit itself and I cannot mass reproduce those.

I am aware either solution will require custom hardware as stated in the original post, but it seems easier to get something that fits in the top cartridge slot, so I will probably just go that route. I can get cartridge connectors all day. That way it would be possible to connect say the 64DD modem cart and boot a 64DD game on a flash cart. I just need to review the pin-outs and draw up a PCB<br/>

<a class="externalLink" href="http://n64.icequake.net/mirror/www.crazynation.org/N64/" rel="nofollow" target="_blank">http://n64.icequake.net/mirror/www.crazynation.org/N64/

I know its possible to make one since the N64 Double slot adapter was an actual dev hardware.

<a class="externalLink" href="http://n64devkit.square7.ch/tools/parts.htm" rel="nofollow" target="_blank">http://n64devkit.square7.ch/tools/parts.htm</a>

I just need to get better pictures of one.

Edit: found some:

<a class="externalLink" href="https://ultra64.ca/gallery/kyoto-microcomputer-co-ltd-k%C2%B5c/" rel="nofollow" target="_blank">https://ultra64.ca/gallery/kyoto-microcomputer-co-ltd-kµc/

Not much to that board. I like the idea of using a 50 pin IDE connector to angle it.
I think I can build one of these fairly easily and add the appropriate pin connections, it wont need the CIC chips or switch. Once prototyped and tested working, off to the pcb mills![/quote]

</div> Nice to hear v64s are getting rare. Makes me glad I haven't sold any of mine recently.
Those links don't provide many details about the board or the things that plug into it but AFAIK the SRAM cart is for saves and doesn't use the same bus as the flash cart. I don't think that adapter does what you seem to think it does.
 

Cybertronic

Newly Registered

<div class="bbCodeBlock bbCodeQuote" data-author="josiahgould">

<div class="attribution type">josiahgould said:

<a class="AttributionLink" href="goto/post?id=988812#post-988812">↑
</div>
<blockquote class="quoteContainer"><div class="quote">Spitballing here... Could you somehow use a GameShark as a passthrough and access the cartridge attached to the back?[/quote]

</div>
<div class="bbCodeBlock bbCodeQuote" data-author="abveost">

<div class="attribution type">abveost said:

<a class="AttributionLink" href="goto/post?id=989708#post-989708">↑
</div>
<blockquote class="quoteContainer"><div class="quote">Nice to hear v64s are getting rare. Makes me glad I haven't sold any of mine recently.
Those links don't provide many details about the board or the things that plug into it but AFAIK the SRAM cart is for saves and doesn't use the same bus as the flash cart. I don't think that adapter does what you seem to think it does.[/quote]

</div> No of course not, I will need a different pinout. I will be building something similar, not an exact copy, but the fact of the matter is that the ext port where the 64DD connects and the cartridge connector up top share the same data lines back to the CPU.

Not all 50 pins are used by the cartridge some are for the ext port and for communication with the cartridge. The ports mirror each other.

This is why if you look on the pinout you will note that the power pin is exactly in the middle of the connector and there is a pin for two separate CIC chips. The 64DD has a CIC chip as does every game cartridge.

The placement of VCC ports also mirror eachother as do the ground points this was done exactly for the purpose of communicating with the cartridge and the 64DD.

The contents of a 64DD disk is essentially the same as a rom image found on a cartridge. This is why we have cartridge conversions of the Disk dumps.

The whole 64dd unit itself is essentially one big magnetic cartridge with a reverse pinout.
 

Cybertronic

Newly Registered

<div class="bbCodeBlock bbCodeQuote" data-author="josiahgould">

<div class="attribution type">josiahgould said:

<a class="AttributionLink" href="goto/post?id=988812#post-988812">↑
</div>
<blockquote class="quoteContainer"><div class="quote">Spitballing here... Could you somehow use a GameShark as a passthrough and access the cartridge attached to the back?[/quote]

</div> That would require streaming the 64DD disk rom through the Parallel port on the back of the game-shark while the cart is attached to the top, but that could technically work given the right software, barring any bandwidth or I/O limitations

<div class="bbCodeBlock bbCodeQuote" data-author="abveost">

<div class="attribution type">abveost said:

<a class="AttributionLink" href="goto/post?id=988867#post-988867">↑
</div>
<blockquote class="quoteContainer"><div class="quote">Whatever you do will require "custom hardware". If you only need one borrow the adapter inside a v64.[/quote]

</div> Its difficult to track down the adapter that fits between the V64 and the Expansion port. They are almost as rare as the unit itself and I cannot mass reproduce those.

I am aware either solution will require custom hardware as stated in the original post, but it seems easier to get something that fits in the top cartridge slot, so I will probably just go that route. I can get cartridge connectors all day. That way it would be possible to connect say the 64DD modem cart and boot a 64DD game on a flash cart. I just need to review the pin-outs and draw up a PCB

<a class="externalLink" href="http://n64.icequake.net/mirror/www.crazynation.org/N64/" rel="nofollow" target="_blank">http://n64.icequake.net/mirror/www.crazynation.org/N64/

I know its possible to make one since the N64 Double slot adapter was an actual dev hardware.

<a class="externalLink" href="http://n64devkit.square7.ch/tools/parts.htm" rel="nofollow" target="_blank">http://n64devkit.square7.ch/tools/parts.htm</a>

I just need to get better pictures of one.

Edit: found some:

<a class="externalLink" href="https://ultra64.ca/gallery/kyoto-microcomputer-co-ltd-k%C2%B5c/" rel="nofollow" target="_blank">https://ultra64.ca/gallery/kyoto-microcomputer-co-ltd-kµc/

Not much to that board. I like the idea of using a 50 pin IDE connector to angle it.
I think I can build one of these fairly easily and add the appropriate pin connections, it wont need the CIC chips or switch. Once prototyped and tested working, off to the pcb mills!
 

abveost

Robust Member

<div class="bbCodeBlock bbCodeQuote" data-author="Cybertronic">

<div class="attribution type">Cybertronic said:

<a class="AttributionLink" href="goto/post?id=989712#post-989712">↑
</div>
<blockquote class="quoteContainer"><div class="quote">No of course not, I will need a different pinout. I will be building something similar, not an exact copy, but the fact of the matter is that the ext port where the 64DD connects and the cartridge connector up top share the same data lines back to the CPU.

Not all 50 pins are used by the cartridge some are for the ext port and for communication with the cartridge. The ports mirror each other.

This is why if you look on the pinout you will note that the power pin is exactly in the middle of the connector and there is a pin for two separate CIC chips. The 64DD has a CIC chip as does every game cartridge.

The placement of VCC ports also mirror eachother as do the ground points this was done exactly for the purpose of communicating with the cartridge and the 64DD.

The contents of a 64DD disk is essentially the same as a rom image found on a cartridge. This is why we have cartridge conversions of the Disk dumps.

The whole 64dd unit itself is essentially one big magnetic cartridge with a reverse pinout.[/quote]

</div> The cart and ext connectors being mirrors of each other has been well known for a long time. That's how all those copiers that sit under the console work. I just don't understand how a dev tool that doesn't do what you're trying to do helps you in any way. If you want something that lets you plug two carts into the top of an N64, and doesn't do what you want, you don't need an obscure dev device. Any region adapter that uses the CIC from a second card will do.
 
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