Copyright © 2006-2017 Petros Savvas, All rights reserved.
Welcome Firmware Diagrams Manuals Support
Adobe Photoshop
Hold down the Option key and select "About Photoshop".

A dialog crediting "Knoll Software" as the original designers appears.
(Contributed by Karl-Koenig Koenigsson)

Claris CAD
Hold down the Option key and select "About Claris CAD".

A system configuration summary appears.
(Contributed by Karl-Koenig Koenigsson)

Disinfectant
Select "About Disinfectant."

A bitmap photo of John Norstad appears in one half of the dialog,
while in the other half an animated sequence of virus names march out
while the Monty Python theme song plays, until they get stomped by
a huge foot.
(Contributed by Dave Claytor)

OS/2

Source: Janos Haide, Panagiotis Skagos

Make the desktop active (i.e., click on the desktop).

Press alt-shift-ctrl-o simultaneously.  You get a beach scene with
a pink flamingo (and other nifty things) plus a list of the program
authors.

Press any other key returns you to your regularly scheduled Workplace Shell.

Macintosh hardware and OS
Get into the debugger
Set PC to 41D789A  (i.e., >G 41D89A at the prompt)

Macintosh II models (exact types uncertain); Mac SE/30 (hardware)

Set the system clock to the American release of the machine [what are
the valid values?  jcm]
Reboot, holding down command-option-model name characters (e.g., on
an FX you hold down cmnd-opt-f-x)

Mac SE, Mac II ci

On a Macintosh SE, hit the programmer's switch, then type G 41D89A

On a Macintosh IIci, first set the date to 09/20/89, then restart
the machine and hold down Command+Opt+c+i during the reboot.

And if you're lucky enough to have an original copy of MultiFinder,
the About box has a simple tremendous list of credits.  But all
is not lost in the newer versions.  Leave the `About MultiFinder'
box open for about an hour.  It will turn into the message [rot13]

System 7

Under System 7 with the Finder running, select "About Finder" on the
Apple menu with the OPTION key to see a list of all developers.  Be
patient, it takes a while.  Using OPTION-COMMAND does that and also
turns the cursor into a smiley.

Commodore 128

Source: Norman St. John Polevaulter  
And of course, going WAY back, there is the credits and anti-war message
you could coax out of a Commodore 128 by typing:

SYS 32800,123,45,6

in BASIC.
Commodore Business Machines 1581 Disk Drive
Source: Eric Pass

   error = $ff3f
  org $3000
  lda #$79
  jmp error

which gives you an author's credit.  Substitute #$7a for #$79 to get a dedication to one of the authors' wives.

Amiga hardware and software

Source: Raymond Chen

On the Amiga (NB), press and hold the following keys:
LeftShift, LeftAlt, RightShift, RightAlt
Now press one of the 10 function keys.  (Keep those four keys down!)
Each function key produces a different message.

To get the rude message, insert a disk into the internal drive.
(Still holding down all those keys?)  Now eject it.

"We built the Amiga..."

   and when you pushed the floppy back in:

    "...and Commodore f**ked it up!"

The rude message has been deleted from newer versions of KickStart.
Get 1.2/33.166 or earlier.

NeXT systems and software

Source: schuetz@ectds.com, also Timothy Buck

In Improv (version 1.0) for NeXTstep from Lotus, go to the Info Panel, and in the space to the left of the Improv title, hold down shift, alternate, and command, and click the mouse.  A "little man" with big bug-eyes shows up....

To clear it, you quit Improv.

Macintosh Plus
From the debugger, enter "G 40E118".
This gives you a "Stolen from Apple Computer" message.

Macintosh SE
Hit the interrupt switch (the button with the broken circle on it, on
the left side of your machine closer to the back) to go into the
built-in debugger, and enter "G 41D89A".
Four bitmap pictures of the Macintosh development team appear as a slideshow.  Reboot (hit the button closer to the front, with the triangle on it) to get out of the endless cycle.

Macintosh Classic
Hold down Command-Option-x-o right after you turn on or reboot the machine.
The Classic starts up from a minimal ROM-disk which contains System 6.0.3, Finder 6.1x, and AppleShare.  (This version of the System is not recommended to run the Classic under.)  If you look at the ROM-disk with a program able to see invisible files (like ResEdit or MacTools), you'll find folders hidden there bearing the names of the Classic designers.

Macintosh IIci
Set the system date to 9/20/89 (the release date of the IIci), and set your monitor to 8-bit color.  Restart while holding Command-Option-c-i.
You'll see a color picture of the IIci design team.  Click the mouse to continue.

Macintosh Iifx
Set the system date to 3/19/90 (the release date of the IIfx), and restart while holding down Command-Option-f-x.
You'll see a color picture of the IIfx design team.  Click the mouse to continue.
Classic Easter Eggs