Also been working on improving mine. Originally I was going with the hexidecimal switch but I decided to be a show off and have it display the current page on 7 segment LED and using push buttons. I am about half done.
Bottom with the new SRAM:
Ignore the extra yellow wire, I ripped up A6 line when I replaced the faulty SRAM with a new one. Tiny pads are not meant to be reheated so many times.
The heart of the new system. I used an older PCB from a project I did about 3 years ago, I had about a dozen left and it was just fine for this project. Green, blue, purple, and white on bottom right goes to the SRAM's address. Brown, red, orange, and yellow is for the 2 buttons plus 5v to go with pullup resistor and ground for switch contact. The rest of wires on top left goes to dual 7-segment display. The color code is for other project and didn't apply to this one.
2 corners are held by hot glue to keep it secure, easy removal if needed. On Duo-R the top side on this area is virtually empty so this would be fine. On Black Duo, the original SRAM would be right under and this will also work with much shorter address wires.
Since I planned to mount the button switch and LED display on the top, I needed for a way to disconnect so I could remove the Duo-R's top completely. I have a bunch of connectors laying around that I just used.
And the switch board I am going to run through OSH Park later:
This board is expecting a typical 0.56" LED display with horizontal pinout and the push button with about 0.4" by 0.3" spacing, about the size of larger PCB mounted push button that can have snap on button top. Plus pin headers, the 6th pin of the 10 pin connector is not used and was intended to function as key with a filled in 6th hole on the connector. I only had 9 pins cable connector, I thought I had 10 so I'll need to get a female socket (Dupont style), the pins are easily transferred.
