This one is a quick update, to let you know I am still alive and making progress!
Aside from the mechanical aspects, I have continued to make progress with the software, making things faster and testing more systems (with outside help). I encountered some issues on older systems that I eventually confirmed were due to voltage levels. An early choice I made was to use bus switches, as I wanted to maintain individual control of direction on pins to keep some options open for playing with a few things like ZoomVideo or other possible functions I was not aware of but may encounter. I now know ZV is outside the scope of what this card can do, so that requirement is no longer needed.
I noticed the issue on the HP 200LX. As I started to get the code faster and optimized, I started to see bit errors periodically. I eventually confirmed that the RP2350 driving the GPIO at 3.3V through the bus switch was not enough for some of these older systems, in particular those with unbuffered sockets.
So I have now made the move to the more standard approach of using LVC16T bus transceivers. As I had already purchased the full qty needed of the other part, I will need to think of a future project to use those if I am unable to return them.
I have completed a lot of exciting work with the firmware and drivers and will share some demonstrations in the coming days as I wait for the hopefully final hardware with the updated bus interface.
The bad news here is that this is for sure going to add several weeks. I am very happy with all other functions of the card, so once I receive the new test boards, likely next week, I am confident I can test very quickly to confirm the bus interface is acting as expected, and I will move on to production quickly.
I am also confirmed for VCF Midwest in Chicago (September 12-13), and unlike all previous years I should have a finished product this time! For taxes and other reasons I will not be selling them in person but I will certainly have some cool stuff on display.