The hacker collective known as NYC Resistor recently told the tale in a blog post of their escapade: reverse engineering the hidden, "Easter egg" photos in the Mac SE ROM.
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.
This discovery created a sensation in some Mac circles around the web, as if this were the opening of Mac King Tut's tomb. Sorry to say, the history is a bit different.
[Note: Trammell Hudson at NYC Resistor complained that this story (or perhaps more the headline) was condescending towards the group and the purpose of their exploration of the Mac ROMs. He said they wanted to "know how they were stored and displayed, and to be able to look for any other surprises stored in the ROM, so further investigation was required."
You've missed the entire purpose of the article on the Mac SE easter eggs, which is to describe the reverse engineering process and disassembly of 68k code for programmers who might not have had much experience with reading and writing assembly.
Hudson was right. I was influenced by the breathless coverage elsewhere and not by the actual NYC Resistor report. David Morgenstern]
Longtime Mac fans — the really longtimers — know that almost all early Macs had virtual and physical "Easter eggs" in them, such as these images stored in the ROM code or the names of the original Mac team imprinted on the inside of the first 128K Mac's case. The Mac SE actually had two such hidden tricks: one of which was the slide show showing the development team.
And there was little need to go deep into the ROM with a probe. Old Macs had a little switch on the side called the interrupt switch, or programmer's key. It was hidden in the air vents on the (left?) side of the case, I recall.
When pressed, a small window would appear on the screen, which provided direct access to the Motorola 68xxx processor debugger. You could then enter a string of code that might or might not do something. To see the slideshow, you would enter G 41D89A and hit return.
I remember that we could enter a similar piece of code into the Mac SE debugger that brought up the message "Stolen from Apple Computer." This recalls the time when the Mac ROM code was stolen and then offered for sale. But that's a different story ...