Commodore Easter Eggs

We’re pretty familiar with “Easter Eggs” on today’s PC platforms.  Basically, these are little tricks the developers hide in their code of say, the Windows OS, and by pressing a certain combination of keys, or by typing in a specific sequence of letters/numbers, a hidden piece of software pops up, usually displaying the names of the developers and some fancy graphics (Microsoft even had pinball and a flight simulator hidden in Word and Excel).

But did we have Easter Eggs on the Commodore as well?  Turns out the answer is yes, although some were not intentional and merely a glitch of some undocumented behaviour of the CPU (a fact that became exploited by developers later on to use hidden and undocumented features of the CPU to make the games better and create stuff on for instance the C64 that was thought impossible).

Here are some Easter Eggs you can try for yourself.

For the Commodore 64:

  • On address $FFF6-$FFF9 (65526-9) in the C64 KERNAL, immediately before the hard-coded jump vectors for the processor, is letter sequence “RRBY”. These are the initials of Robert Russell and Robert Yannes, the two main engineers that created the C64.
  • Due to a glitch in the C64’s BASIC operating system, an unintentional Easter “screensaver” may be activated by first holding the RUN/STOP key, tapping the RESTORE key, then entering POKE781,96:SYS58251 on the subsequently cleared screen.
  • As with all Commodore machines running BASIC, typing 350800 and hitting Enter leads to unpredictable results due to a bug in the BASIC interpreter.

For the PET-line of Commodores:

Because Bill Gates (as he would state later on) made his very first business mistake in agreeing for a one-time license payment of Basic by Commodore, instead of the per unit model he wanted (it would have made him rich much faster!), they had built-in an easter egg into the original Commodore Basic: typing the command WAIT 6502, 1 would result in Microsoft! appearing on the screen (showing that they were the once that build BASIC).   It wasn’t until the Commodore 128 (with V7.0) that a Microsoft copyright notice was displayed on screen.

For the Commodore 128:

Because of the RAM shortage in early PETS Commodore disk drives were little computers in themselves with DOS in ROM and you would send commands to them and then read the error channel to see how the disk drive had carried out or failed to carry out the command.  A Commodore and its peripherals really operated as an early computer network!
The 1581, a 3 1/2″ disk drive, made primarily for the C’128, and it had these easter egg commands (it might be diffucult to test these now, as 1581 drives are prime eBay-auctions and fetch well over €100.

100 input “Device number of 1581”;dv
110 rem first disk drive = 8, 1581 usually dv = 9
120 open 1,dv,15: rem 15 = command channel
130 for i=1 to 2
140 read cm$
150 data uj,uk
160 print#1,cm$: REM send the command to the drive
170 input#1,a$,b$,c,d
180 Rem get the error channel output
190 Rem a$ = command error number but may be 7: here
200 Rem b$ = descriptive error
210 Rem c, d = track, sector #–0,0 here
220 print a$,b$,c,d
230 next

Command: “UJ” or “U:”
Error: 79,software david siracusa. hardware greg berlin,0,0

Command; “UK” or “U;”
Error: 7:,dedicated to my wife lisa,0,0

There was even a Easter Egg for the Commodore app on the iPhone (!!), which, once it was discovered, let to the immediate removal of the app until it was fixed.  The cool thing was, that it really showed that the Commodore app on the iPhone was a true C64 emulater, with the full BASIC interpreter underneath.  The Easter Egg, basically allowed you to cleverly “reset” a game and end up in the Commodore start-up screen, greeting you with the familiar “READY”-prompt.

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