I have found that the slot extenders for the Apple 2 have been out of stock for some time now.
So I designed a PCB with Kicad and had 5 cards made by PCBWAY .
All worked well but the card edge to fit the slot was a little to short at each end and whilst it was electrically sound did not sit well with me as a finished product.
So a second version has been run up in Kicad and hopefully the card edge to slot will now be a snug fit.
Whilst I do not intend to sell any of these slot extenders, I will make the Kicad files avaiable on GitHub if any one is interested?
I thought it might be interesting to show you the proposed item and find out if there are things that should be included in the design.
The PCB's are fabricated as one part which can be sepearte into two parts and then joined with a 30 cm 50 way ribbon cable.
Power lines are isolatable and also provide a point at which to measure current to the board under test.
I have also included provision for soldeless breadboard patch pins to be pluged in to monitor the signals on the Apple bus.
Also is "Apple 2 slot extender" the righ name to describe the PCB.
Would it be useful to have a ribbon cable to solderless breadboard connector?
![Apple][ slot extender PCB](https://www.applefritter.com/files/styles/95-percent/public/2025/08/05/Screenshot%202025-08-05%20142922.png?itok=WvspkUmF "Apple][ slot extender PCB")
![Apple][ slot extender 3D render](https://www.applefritter.com/files/styles/95-percent/public/2025/08/05/Screenshot%202025-08-05%20143440.png?itok=NLfOzz3N "Apple][ slot extender 3Drender")
Very Nice! Let us know if you plan on offering PCB's to the community.
I'm suggesting you use ENIG surface traces for anti-corrosion and that "gold" look.
The expense difference is usually a minor increase from tin coated traces.
Thanks for the input .
I did indeed have the first cards finished in tin and will try ENIG for the second run of 5 cards and the price difference will be interesting to see.
I expect to develop a few more options around this passive card and they will all eventually be on GitHub under free collect commons conditions. So available to all.
I would expect if anyone runs a commercial operation with these designs, when published, that they donate a small percentage of any profit to Kicad.
I will probably be sending the design to PCBWAY this weekend, but I may opt for slow post, as £25 for 5 cards is quite a hit, so it may be 5 weeks or so before I can say more.
Regards Crusty
This looks pretty nice.
You could even use two of these cards with a 50 pin IDC cable to put a slot outside the case.
The original post mentions it is part of the design to be able to separate one board into two pieces and use a cable to extend the slot.
Justin
Yes, I see that now. I didn't get that from reading the original message but now that you pointed it out I see where you can cut the board in two and join it with the cable. The connectors make sense now. I was wondering why the IDC connectors were orriented like they are but it makes sense now.
Is there anything that needs to be added to this passive design?
If not I will be sending the file to PCBWAY this weekend and if card edge is correct when it arrives I will put design on GitHub and advise AppleFritter with a link.
It may be a couple of weeks as being on a pension postage will be slow boat from China.
Many thanks to all that have shown interest in this tiny project.
Crusty
how about adding silkscreen text for each pin?
Sadley too late for version 2 ,as has gone to AISLER for fabrication.
I will try to see if i can get a silkscreen text for the test pin area in.
To keep costs as low as possible I need to keep board size to the minimum .
I will move the card edge socket down nearer to the 50 way socket and move the pin/socket header down the board and then see if I can get the standard apple bus names against the pins.
Next addition is the 50 way cable to solderless breadboard PCB and I will make sure the breadboard plug in pcb has pin text for the bus names.
Thanks for the input.
Version 2 of my Apple Slot Extender has arrived from AISLER and the cardedge detail is now acceptable, with just the smallest margin lengthwise to allow insetion into an Apple 2* 25 slot.
Version 2 looks no different from Version 1 except for the ENIG gold colour on the traces and card edge traces.
The cost of ENIG from the previous China fabricators along with a very high postage cost, made me look for a UK or EU supplier.
AISLER have done a terrific job of taking the Kicad 9 project to completion with only a few Euro's differnce when asking foe ENIG finish and very resonable postage costs from Germany to UK.
I have designed but not had made a Version 3 with the slot names as suggested by "dorkbert".
I feel sure that the card edge will be fine as it uses the same size adjusted card edge profile as Version 2.
Not all of the design is my work as I asked GitHub contributor "markdev " if I could use one of his card edge footprints and you can see his very kind reply agreeing to my use of his hard work.
"Hey there, yes that would be OK. The footprint is in this file https://github.com/markadev/AppleII-VGA/blob/main/AppleVGA/AppleVGA.pretty/AppleIIBus_Edge.kicad_mod which you can copy into your own project.
I also have another footprint in this library: https://github.com/markadev/KiCad-AppleII HOWEVER it contains some small size adjustments from the one used in this project and I never got around to creating a board to test it. So it's a bit more of a risk to use."
I am not going to make a plug in module for solderless breadboard as a 2 * 25 way plug is hard to push into and release from the breadboard .
With already having pins or sockets on the extender card standard Dupont patch wires should be enough to facilitate connection to solderless breadboard.
PLEASE BE SURE TO PLACE ANY CARD INTO THE 50 WAY SOCKET THE CORRECT WAY ROUND AS THERE IS NO CASE BACK TO MAKE SURE THE CARD POINTS TO THE KEYBOARD>
A CARD INSERTED IN THE WRONG DIRECTION WILL PROBABLY KILL THE CARD AND THE APPLE COMPUTER?
As previously mentioned I have made version 2 and 3 available at GitHub, please be aware that it is the first time I have posted on GitHub and if I have missed some of the Kicad files needed to complete the project let me know and I will add or subtract files as required on Github.
I would suggest running up your own project from my files to ensure the resulting PCB can be sent without error to your fabricator.
Link to Kicad version 2 and version 3 on GitHub
Regards Crusty
3D V3 slot extender.png
Looks great. It would also be pretty useful for the Laser 128, especially if a box was made for holding the external slot. A version for the Laser 128 with two slots and splitting the two that the Laser 128 supports would be cool. I know others have done that before but in some ways those are not quite as nice as this project. Another cool option would be to make the external slot portion easily support the external cards being powered by an outside power supply. So many things that can be done with something like this.
Crusty, I used to have use of a 6" tall 50-pin slot extender board that plugged into any Apple IIx backplane slot and provided a 50 pin female Cinch slot connector with shared centerlines, on the other end. Keeping the raised female slot connector in the same vertical plane as the Apple's insured that any adjacent boards in adjacent slots would not be interferred with. This was a terrific aid and reduced time-on-task when troubleshooting 6 layer co-processor boards consisting a 65C02 CPU, w/32KB of SRAM, four 8-bit Multiplying DAC outputs, a 4 channel analog mux that controlled the DAC multiplying input's signal source, and 3 digital I/O outputs when a board issue came to light.
I've got a stack of these boards I've been needing to finish fixing and you extender looks like a winner.
Unfortunately the 6" slot extender I used 40 years ago belonged to my co-designer friend. I found a similar one on Ebay a few years ago but it was only a 4" tall slot extender and not nearly as useful due to its shortness.
I think I like your solution even better! Thanks again!!
And a shoutout to dorkbert for the pin text labels!
ps: I've also created an Apple II double-sided edge connector and board layout in KiCAD 8. I've never had any boards made of it yet, however. I'm more than happy to share if anyone is interested.
ps2: I've downloaded your GitHub zip of the KiCAD project, but when I open the project and select to view the PCB all I see are the board outlines and Front Silkscreen text. No traces. Possibly missing footprint libraries, too?
Hi,
As I said, first time trying to post a project to GitHub.
I also included a zipped archive file of each project, have you tried to unarchive this file.
Perhaps some one could walk me through the best process of getting my project files into GitHub so there are no errors.
I can also post the files I download to my PCB Producer if this helps.
I find Github can be a bit difficult to work with.
I have just upload a new V3 project which is in the previous V3 project and this time I hope I have included the footprint and schematic items needed.
I have a RPi4 to download to as a sandbox but it not running version 9 of Kicad, so if someone can try to open the V3 project that now contains Library.pretty we may be getting there.
If openable then I will start a new repositry knowing how I am doing things to get it right to share.
Regards stay with me Crusty.
Hi all,
I have had yet another go with uploading my Kicad 9 project to GitHub
https://github.com/MrCrusty/APPLE-SLOT-EXTENDER/tree/main/Bus_Extender_V3
It's now in a folder BUS_EXTENDER_V3 and I think this will have the symbol and footprint files.
Regards
That my normal thing to do is get the zip archive.
Good news. Your updated version of the Apple_Extender_Socket_V3 contains the edge connector and footprints in the PCB.
There was no way to download a zip version of your last efforts, and like you I'm no expert on GitHub. I could see files and folders, possibly update them but not download them.
The APPLE_EXTENDER_SOCKET_V3 and Bus_Extender_V3 folder project files looks great as well, 3D viewer and all. Good work and thanks!
Hi All thanks for coming along on my learning process.
I have just updated the repository at GitHub V2 & V3 bus extender link.
There have been a number of issues to deal with.
Kicad first.
I had not realised that I needed to have a brand new folder for each project , so the GitHub folders became very convoluted and unusable.
I had also not realised that I needed to export the symbol and footprint files to the project, I thought that happened automatically, silly me.
I suggest that if you use a local copy of the project you should import the symbol and footprint files with the project option rather than global.
There is a one design rule check outstanding in the PCB design Check.
This is for the Dupont connector and I will have to get that sorted though it does not cause any wiring problem, probably as I use global labels rather than pin numbers for the nets.
I like to get no errors on a check so in time this will be changed.
In respect to the GitHub repository.
It took me a long time, but not on this project, to learn how to get files downloaded.
There is a GREEN button on the repository landing page labeled "CODE" click on this and then click on "Download zip" option.
You will get the total repository downloaded and can then unzip and then click on the V2 or V3 folder and then click on the Kicad project file at which time the project should open. You may still have to adjust some of the references to files.
At 80 years of age its great to regain some of the early years passion again.
My first use of an Apple 2e was to match and code a Bruer and Kajal sound level meter so that it would record noise of road buses and tube trains to disk and then plot to a Roland Pen Plotter.
Hi,
I do not have a Laser 128, but I am working on a backplane on a eurocard format, for dare I mention, yet another re_invention of the Ohio_Scientific SuperBoard and its UK clone UK101 and a Z80. My plug in cards for this will be standard eurocard but pluged upright in the slot as my Backplane will be vertical.
Its a work in progress as I like the 2 * 25 card socket adopted by Apple designers, they have certainly stood the test of time and the slot are still in production and avaialble.
It could have variants but I have not researched the Apple select lines for each socket. Are the individually selected on the Apple base board? Or just daisy chained as I have them at the moment on this variant.
Quite happy to work with anyone to add extras for 6502 hobby project.
Regards Crusty
Backplane.png