Trammell Hudson and phooky of NYC Resistor have been exploring read-only (e.g., non-volatile) memory chips in a series of fascinating posts on the hackerspace’s blog.
phooky wrote The Joy of Dumping, which explains why you’d want to check out the ancient data moldering on decades-old chips:
Which brings up the question of why you’d even want to bother to begin with. This is the firmware for an obsolete solvent control system running on a Motorolla 68000 microprocessor, obscurity on obscurity on obscurity. Who’s ever going to need it anyway? Why save the bits?
For the same reasons we record any history: because someday it may prove to be useful, and because someday it may prove to be beautiful. And even if it’s neither, at least it’s fun to poke around. Just pulling the strings out of the binaries yields odd puzzles.
In Stick a Straw in Its Brain and Suck: How to Read a ROM, phooky shows how to dump a ROM.