Since the Vectrex itself can only address up to 32kB ROM on the cartdridge port you need to do some trickery called bankswitching if you want to have more. You can use several dedicated logic chips for that or just develop your ouwn logic circuit and program it on a PLD (programmable logic device). And that luckily still works fine on my old dusty windows machine:
Now I can finally produce my 512k carts (or bigger) again. Good for really big games or game collections like multicarts. If everything goes well, Friday is the day they are done:-)
Then I converted 5 cheap mega drive gamepads for Vectrex usage and made 20 colour wheels for the Imager. I have to see if the wheels are dried before the post arrives, otherwise the next imagers will leave on Tuesday.