I’d installed 64 MB of RAM in my Macintosh IIcx as I wanted to install NetBSD on it, and UNIX needs all the memory it can get. However these computers perform a memory check on startup that can take up precious seconds of your time, especially when a large amount of RAM is fitted. The instructions for this memory check are stored in the Macintosh ROM. I want to change that ROM and disable it… The logic boards of these ‘030 Macs have a socket that can accept a ROM in the form of a 64-pin SIMM module. There are already newly manufactured flash based ROM SIMMs available to purchase, like BMOW’s ROM-inator II, but I figured I might as well save some pocket change by assembling one myself. I already own a ROM programmer. (more…)