In tribute, I ran a Google search on PR#6 to see what turned up. For those who don't know or don't remember, PR#6 was the command that kicked off the bootloader code for slot 6, the drive controller. The search turned up two relevant links: an Apple TechTip on a simple copy-protection scheme, and a fantastic blog entry that covers a bit about the Apple ]['s boot process, which brings back a lot of memories of old Shugart drives, including the terrifying sound of a track 0 seek – a process wherein the drive head was moved across the disk very quickly until it physically couldn't go any further, resulting in a loud alarm-like buzz from the drive when it hit the limit of its reach.
Anyway, in celebration of the Apple ]['s 30th birthday, I recommend grabbing your nearest emulator, and banging in a
call -151for old time's sake.