The Nintendo 64 used RAMBUS memory, width 9 bits including parity; the latter would seem unnecessary for a console, but the machine actually uses it to store an extra bit of data.
This is an unusual design choice (relative to just omitting parity), and I'm curious about the reasoning. Is it that they particularly wanted exactly 18 bits per word, and this was the way to get it? Did it happen to be the case that the best deal they could get on memory modules included a parity chip for less than 1/8 extra money? Would the same idea also work on the more commonly used EDO RAM?