Get the latest tech news
Diode Matrix
A diode matrix is an extremely low-density form of read-only memory that was used in computers in the 50s through the 70s, before EEPROMs were invented. (They are actually still used, but only inside microchips, not using discrete diodes.) Each bit in the ROM is represented by the presence or absence of one diode.
A diode matrix is an extremely low-density form of read-only memory that was used in computers in the 50s through the 70s, before EEPROMs were invented. The ROM is easily user-writable using a soldering iron and pair of wire cutters. This particular diode matrix board is a floppy disk boot ROM for a PDP-11, and consists of 32 16-bit words.
Or read this on Hacker News