I found a reasonably priced prototype card ($10 plus shipping) on Ebay which plugs into the Apple-1 44-pin connector.This card is meant for the Commodore VIC-20, but the edge connector is the same and none of the edge connector pins is prewired to anything, so we can use it in the Apple-1. The inscription on this card is "VICProto rev 0 (c) 2019 Will Cooks Small Time Electronics". Alas, I could not find any more of them. So I'm posting this in hopes somebody reading this might have a hint.
Here is how it looks:
And here is how its internal power / ground grid (which, alas, has pathetically narrow traces) can be hooked up to the edge connector to make it work in the Apple-1:
I put a 47uF electrolytic capacitor into the two through holes at the lower right corner of the card (which appear to be meant for that) and jumpered the (-) lead of the capacitor to edge connector pin 20 (note the heat shrink tube for insulation), and the (+) lead of the capacitor to edge connector pin 22. On the component side I soldered in a small jumper loop from connector pin 20 (GND) to the nearest ground rail. This loop is meant to clip scope probes to. The other GND finger is left unconnected.
Here is how the card looks in an Apple-1 (Apple-1 not fully populated, only the ICs needed to make the CL clock are in it):
Using this platform, I intend to investigate a few options to derive a faster clock from the CL clock. This is the first step towards a new peripheral for the Apple-1. So over the next weeks, this card will get more and more populated with more ICs. At the moment there is only one 8-pin socket seen which is meant for a 555 timer. The next step is to make that 555 work and measure what its fierce current spikes do to this suboptimal power / ground grid. It is not a part of the planned clock generation circuit, though. But I want it to be there to hammer the power / ground grid so as to see which clock generator is more robust against such an evil thing on the same PCB.
Just wanted to show you this nice and reasonably priced prototype card, which, I hope, saved me from the boring tedium to design, layout and getting manufactured a prototype card of my own.
I probably would have use the same smart concept with the power rails running between the pin rows of the IC sockets and then having short traces with three through-holes at each IC pin. The only thing I would want to be improved is the power / ground grid. It could greatly benefit from wider traces. And, of course, gold plated edge connector fingers. But this is just a PCB manufacturing process option.
Does anyone have a hint where I could find more of these cards ?