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2 Port Cartridge Expander


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Last year I was able to accomplish moving my 99/4A, Speech and PEB assembly to an older PC AT case


Message thread HERE


With help from Tursi answering my questions I was able to work out a design (all hard wired) for a 2 port cartridge expander that plugs directly into the 4a cartridge port on the main board. With a flip of a 3PDT switch I can switch between the 2 ports. Installed a reset switch with it.


Well, I finally took some time to design an actual PCB for it. I had to design the 36 pin Eagle library for it too. I still need to design a small PCB (cartridge end that will be soldered to the middle of the board by a 90 degree pin header.


I still need to verify the board again and again. Once I verify all traces a few more times then I may send it off to Oshpark to get made.


Wanted to share it.


I have updated the photos to a smaller footprint as to reduce cost as well as space required within my all in one unit.


This will require a cartridge extension board. A simple 36 pin (18x2) board. This board will plug into the F3 connector that plugs directly into the 99/4a mainboard.


Added photos for my hand wired development board that I am currently using in my All-In-One PEB. I used 30 AWG solid core wire wrap wire to make the connections.










Edited by Shift838
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This is precisely what I want to do for the 4 port version but I need to learn the software. Are you going to make the file available? Would be a great starting point.


Yes, once I verify all traces again and again, i plan on releasing the drawing, schemattic and even the eagle library files I created.


I need to figure out how to make the doublesided cartridge board in eagle now with the finger type contacts..

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I have updated the photos and schematic. One, was that to reduce the cost to tool the board I reduced the footprint. I was also going off memory last night and did not look at my connectors. My middle connector (F3) I thought was the standard spacing and well, it was not. So I fixed that.


also added the cartridge extension PCB to use between the mainboard and the 2 port expander on F3.

Edited by Shift838
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