Rewritable ROM disk for Mac Plus: achievement unlocked. http://www.bigmessowires.com/2014/12/20/rewritable-rom-disk-for-mac-plus/
Bbraun put together a new version of the Plus ROM adapater board, with one extra chip on it for generating the correct output enable signal for the flash ROM. Then I dusted off my Metrowerks Codewarrior skills, and wrote a little Macintosh program to do the in-system flash update. It helps that I recently did almost exactly the same thing for my 68 Katy breadboard computer, which coincidentally used the exact same flash ROM chip, and a 68000-family CPU, so I knew it could be done.
The Mac program reads 128K of data at a time from the image file you select, then disables all interrupts, does the magic incantations to unlock the flash ROM, and writes the new data to flash. It takes about 60 seconds to update the entire 1 MB contents of flash memory.
View attachment 4997
Bbraun put together a new version of the Plus ROM adapater board, with one extra chip on it for generating the correct output enable signal for the flash ROM. Then I dusted off my Metrowerks Codewarrior skills, and wrote a little Macintosh program to do the in-system flash update. It helps that I recently did almost exactly the same thing for my 68 Katy breadboard computer, which coincidentally used the exact same flash ROM chip, and a 68000-family CPU, so I knew it could be done.
The Mac program reads 128K of data at a time from the image file you select, then disables all interrupts, does the magic incantations to unlock the flash ROM, and writes the new data to flash. It takes about 60 seconds to update the entire 1 MB contents of flash memory.
View attachment 4997