Here's a fun one for somebody:  What are the individual histories of
the Scroll Key, Print Screen, and Pause|Break key on PC keyboards...
and what functions, if any, do they serve today?

Here are excerpts from a most excellent explanation of "Scroll Lock"
and "Pause Break." This comes from one of the most informative (and
entertaining!) online reference sources, "The Straight Dope." I
recommend that you read the entire article, if you have the time.
There's some good info here, and (in typical "Straight Dope" style) it
is very well presented:

"The Scroll Lock key has appeared on the keyboards of IBM personal
computers since the original 83-key PC/XT and the 84-key AT layouts,
and remains on the 101-key and greater 'enhanced' keyboards currently
in use. The Scroll Lock key wasn't on the original Macintosh keyboards
but appears on the Mac's 'enhanced' keyboard.

The main intent of the Scroll Lock key was to allow scrolling of
screen text up, down and presumably sideways using the arrow keys in
the days before large displays and graphical scroll bars.

[ . . . ]

The Pause/Break key was used in the DOS command line environment to
pause scrolling of text on the screen, which could, depending on the
program and its method of text output to the screen, have the effect
of pausing program execution... The Break key, when combined with the
Ctrl key, is used to terminate DOS applications - and still does
today, even in the DOS window of Windows XP."

The Straight Dope Mailbag: What's the "Scroll Lock" key on my computer for?
http://www.straightdope.com/mailbag/mscrolllock.html

As for "Print Screen," this one is not nearly as obscure. In the olden
days of DOS, the key was useful for sending material to your printer.
Today, in most versions of Windows, the PrintScreen key captures an
image of the entire screen and places it in the clipboard
(Alt-PrintScreen captures an image of just the active window.) The
user can then paste the image into an image editor for... well...
image editing. This is very useful for acquiring images from sites
which have disabled right-click (one should, of course, honor the
copyrights of such sites by not making commercial use of images
acquired by the use of PrintScreen.)

"Print screen key: Often abbreviated Prt Scr, the Print Screen key is
a useful key supported on most PCs. In DOS, pressing the Print Screen
key causes the computer to send whatever images and text are currently
on the display screen to the printer. Some graphics programs,
including Windows, use the Print Screen key to obtain screen
captures."

Webopedia: Print Screen key
http://www.webopedia.com/TERM/P/Print_Screen_key.html 

Here's a useful collection of definitions of computer keyboard keys:

ComputerHope: Keyboard Definitions
http://www.computerhope.com/jargon/keyboard.htm

More good reading on the subject of the mystery keys:

RinkWorks: Re: Mysteries of PrtScrn, Scroll Lock, SysRq, Pause, Break, Esc
http://rinkworks.com/rinkforum/messages/47458.shtml

Mail.gnome.org Archives: Re: [Usability] Print Screen and Pause keys
http://mail.gnome.org/archives/usability/2002-February/msg00165.html

Steve Maurer Publications: Using the "Print Screen" key
http://www.steve.maurer.net/tutorials/computer_tutorials/printscreen.htm

Prescott Computer Society: Special Keyboard Keys
http://www.prescottcomputersociety.org/html/101_8_01.html

Google Web Search: "history of" + "key" + "scroll lock" + "pause break"
://www.google.com/search?hl=en&ie=UTF-8&oe=UTF-8&q=%22history+of%22+key+%22scroll+lock%22+%22pause+break%22

Google Web Search: "print screen key" OR "printscreen key"
://www.google.com/search?hl=en&ie=UTF-8&oe=UTF-8&q=%22print+screen+key

Thanks for another enjoyable question! Please let me know if anything
needs further explanation.

Best wishes,
pinkfreud

---

Request for Answer Clarification by jhabley-ga on 08 Jan 2004 14:02 PST

Thanks - any idea what SysRq does? That's the text on the same key as Print screen?

---

Clarification of Answer by pinkfreud-ga on 08 Jan 2004 14:11 PST

Regarding 'SysRq', I can't improve on this, from "The Straight Dope":

"Other odd keys worthy of note on your keyboard include the SysRq key
(sometimes appearing as SysReq), which shares the same key as the
'Print Screen' key. (Historical sidelight ? SysRq was the '84th key'
added when the 83-key PC/XT keyboard became the 84-key AT keyboard.)
Unless programmed by a particular application, the SysRq key does
nothing in most operating systems, including DOS, Windows, and OS/2.
The SysRq key has different 'hooks' into the system BIOS (basic
input/output system, the interface between the software and the
low-level functions of the computer) from the other keys on the
keyboard. IBM evidently included this key to facilitate task switching
in future operating systems ? that is, to allow either switching from
one task to another (as on a mainframe computer), or interrupting all
tasks and returning control to the keyboard. Advanced MS-DOS
Programming, second edition, Microsoft Press, states:

A multitasking program manager would be expected to capture INT 15H so
that it can be notified when the user strikes the SysReq key.

In layman's terms that means, 'you can make a multitasking program
manager monitor a specific location in your computer's hardware so it
can do something cool, such as letting the user switch tasks, when the
SysReq key is pressed.' As it turned out, the developers of Windows
didn't use SysReq when implementing task switching. Some new keyboards
no longer feature this key, and its days seem numbered."

http://www.straightdope.com/mailbag/mscrolllock.html

The sysRq key (system request) was used on the 4680 and 4690 operating
systems. These OSs were used within the IBM general retail application
that retail stores like WalMart, Target, KMart used. (I don't know
whether they still do.) The key allowed access to the system menu so
the operator could start a new window or task while the machine was
busy doing something else.

The Scroll Lock key does at least have one use today: when you enable
Scroll Lock in Excel, pressing the arrow keys will not select another
cell, but will instead scroll the sheet.

The most interesting answer for everybody would be the one on
"hOW DO I KILL THAT DAMN CAPS LOCK KEY FOREVER!"
 ;)

To "kill that damn caps lock key forever," use this free utility:

"CapsUnlock supersedes the locking mechanism of the CapsLock key and
thus prevents the accidental turning on of CapsLock. It runs as a
little tray application in the taskbar. The user can select an
override option, which allows CapsLock to be switched on and off by
holding down the left Shift key while pressing CapsLock. Furthermore
CapsUnlock also disables the Insert key."

BrainSystems
http://www.brainsystems.com/capsunlock/

Works like a charm. Although you can override the program if you want
your CapsLock key back, I've never done so. Death to the CapsLock key!
;-)

Hello pinkfreud-ga,
I found another interesting Website - no need for another software
eating up pc memory:
http://johnhaller.com/jh/useful_stuff/disable_caps_lock.asp

Goodbye CAPSlock.