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Keys, Special single-keystroke functions – HP D315 User Manual

Page 172

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Appendix C Keyboard


C.2.4 KEYS

All keys generate a Make code (when pressed) and a Break code (when released) with the
exception of the

Pause

key (pos. 16), which produces a Make code only. All keys with the

exception of the

Pause

and Easy Access keys are also typematic, although the typematic action

of the

Shift

,

Ctrl

,

Alt

,

Num Lock

,

Scroll Lock

,

Caps Lock

, and

Ins

keys is suppressed by the

BIOS. Typematic keys, when held down longer than 500 ms, send the Make code repetitively at a
10-12 Hz rate until the key is released. If more than one key is held down, the last key pressed
will be typematic.

C.2.4.1 Special

Single-Keystroke Functions


The following keys provide the intended function in most applications and environments.

Caps Lock

- The

Caps Lock

key (pos. 59), when pressed and released, invokes a BIOS

routine that turns on the caps lock LED and shifts into upper case key positions 40-49, 60-68,
and 76-82. When pressed and released again, these keys revert to the lower case state and the
LED is turned off. Use of the

Shift

key will reverse which state these keys are in based on the

Caps

Lock

key.

Num Lock

- The

Num Lock

key (pos. 32), when pressed and released, invokes a BIOS routine

that turns on the num lock LED and shifts into upper case key positions 55-57, 72-74, 88-90,
100, and 101. When pressed and released again, these keys revert to the lower case state and the
LED is turned off.


The following keys provide special functions that require specific support by the application.

Print Scrn

- The

Print Scrn

(pos. 14) key can, when pressed, generate an interrupt that initiates

a print routine. This function may be inhibited by the application.

Scroll Lock

- The

Scroll Lock

key (pos. 15) when pressed and released, invokes a BIOS

routine that turns on the scroll lock LED and inhibits movement of the cursor. When pressed and
released again, the LED is turned off and the function is removed. This keystroke is always
serviced by the BIOS (as indicated by the LED) but may be inhibited or ignored by the
application.

Pause

- The

Pause

(pos. 16) key, when pressed, can be used to cause the keyboard interrupt to

loop, i.e., wait for another key to be pressed. This can be used to momentarily suspend an
operation. The key that is pressed to resume operation is discarded. This function may be ignored
by the application.

The

Esc

,

Fn

(function),

Insert

,

Home

,

Page Up

/

Down

,

Delete

, and

End

keys operate at the

discretion of the application software.


hp/Compaq Personal Computers

Changed - April 2003

C-8