I've been working on a new memory board for the Apple ///, using (somewhat) modern and still-in-production components, especially CMOS static RAM rather than DRAM. Last night I soldered the connectors, sockets, and passives of my first prototype: https://flickr.com/photos/_brouhaha_/albums/72157719738576267 I need to do some testing for shorts, etc. before I attempt to actually use it in an Apple ///. I expect that some debugging of the design will be required. The Apple /// design is _much_ more complex that the Apple II and IIe. I intended this board to provide 512KiB of RAM, but I've already determined that some design changes will be required for that, so this prototype will only support 256KiB. The early Apple /// design, as documented in US patents, would have supported up to 512KiB of RAM, but the actual shipped design reduced that to 256KiB. There was a third-party 512Kib emory board from "On Three", which required pulling various chips from the motherboard and running cables from those to the memory board. The SOS operating system, as shipped, only supported 256KiB. On Three modified the SOS bootloader to detect and use 512KiB. Some Apple /// application software also had trouble with 512KiB, and On Three patched some of those.