The Lost 256 KB Japanese ROM for the Macintosh Plus Has Been Found
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Summary
Pierre Dandumont has apparently managed to get hold of a 256kB ROM for vintage Apple Macintosh Plus computers, said to have been used in Japan to support Japanese characters.
The larger size meant it could save valuable RAM and loading time for the Japanese language extensions.
However, it appears that its existence was rumoured for years before Dandumont’s discovery, as no one had found one outside of Japan to examine.
The secret to the larger capacity turned out to be an extra address line needed for the larger ROM size, which was implemented as a voltage pin in the MAC ROM socket.
With this knowledge, Dandumont was able to dump the ROM, and it has now been made available for vintage Mac enthusiasts.
