The folks at the NYC Resistor hackerspace found a Macintosh SE that had been abandoned on a Brooklyn sidewalk and decided to conduct a little "digital archeology."
While digging through dumps generated from the Apple Mac SE ROM images we noticed that there was a large amount of non-code, non-audio data. Adam Mayer tested different stride widths and found that at 67 bytes (536 pixels across) there appeared to be some sort of image data that clearly was a picture of people. The rest of the image was skewed and distorted, so we knew that it wasn’t stored as an uncompressed bitmap.
After some investigation, we were able to decode the scrambled mess above and turn it into the full image with a hidden message from “Thu, Nov 20, 1986“
They say there's more curious data in the ROM that they haven't been able to decipher yet.
Mark Frauenfelder is the founder of Boing Boing and the editor-in-chief of MAKE and Cool Tools. Twitter: @frauenfelder. His new book is Maker Dad: Lunch Box Guitars, Antigravity Jars, and 22 Other Incredibly Cool Father-Daughter DIY Projects