I have PCBs and connectors arriving tomorrow for a prototype of a new Apple /// memory board, using modern components (e.g., CMOS SRAM). The initial version is a 256 KiB board, as proof of concept. Is this something anyone might want?
Compared to the Apple "5V" memory board, this uses much less power, so it doesn't need the power resistor from +12V to +5V that was present on the Apple board, and it puts less load on the power supply and generates less heat.
This new board will REQUIRE a "5V motherboard". In other words, the motherboard has to have the 5V PROMs, and R58 removed, and the mohterboard jumper installed. Any Apple /// that currently works with a 5V memory board is properly configured, as is any Apple ///+. Apple /// motherbards that currently work with a 12V memory board will not be compatible, unless the motherboard is upgraded to the 5V configuration.
And before everyone asks, yes, I know that everyone wants a 512 KiB board, like the On Three board. That's quite a bit more complicated. Although I've given it some thought, and my first board was designed with the intention of being capable of 512 KiB, I've already discovered that the current board design won't be able to do it.