Figure 1

Figure 1

The numlock key (meaning “number lock”) is used for switching the function of keys that can be either numbers or something else. When the keys are acting as number keys the result is the same as pressing the number keys at the top of the keyboard. So why have both? Well, the second set of numbers is grouped so as to be more convenient for people entering loads of numbers (as opposed to text – see figure 2).

Figure 2

Figure 2

. For example, on the keyboard in figure 2, when the numlock key is selected for numbers then hitting the letter “u” will produce a figure 4.

The numlock key is an example of a “toggle switch”. Whatever the current function, pressing a toggle switch will change to the opposite function (or cycle through the different functions if there are more than two). So, if you want to change back from number keys to ordinary letter keys you just press the numlock key again.

You can usually find a little LED light somewhere that goes on and off depending on the state of the numlock switch. It will usually be labelled “num” or “numlock” or have a figure 1 inside a padlock (see figure 1).

So, for the average user, the numlock key is quite possibly never used (except when it’s hit by accident).

The caps lock key is another toggle switch. When it is activated all of the characters A-Z are typed as capital letters.

Caps lock and shift keys

Figure 3

This is fine if you want to type many consecutive characters as capitals, but if you just want to capitalise the first letter of a word then it is quicker to depress either of the two “shift” keys and then type the letter to be capitalised while the shift key is down. On most keyboards there is a shift key at both the lefthand and righthand edges of the keyboard. They are functionally the same as each other. They are usually indicated by a label of an upward pointing arrow (see figure 3). There is usually a labelled LED light to indicate the state of the caps lock key, typically labelled with a letter A inside a padlock.

Scroll (or Scroll Lock), Sys Rq, and Pause/Break Keys

Although all these keys used to have specific purposes, these days they are little used. Some programs do use them in very specific ways but you might need to consult the program manual to find out about it. I don’t think I ever use any of these keys.

Delete Key vs Backspace

The backspace key (near the top righthandside of the keyboard, with a left-pointing arrow – see figure 1) deletes the character to the left of the cursor and moves the cursor left by one character. Therefore, if you hit the backspace key repeatedly (or just keep pressing it) it keeps deleting the text to the left of your current cursor position – ie it deletes what you have just typed if your cursor is at the end of the typing (the cursor is the flashing icon that tells you where on the screen your typing or editing is currently happening).

The delete key works in the opposite direction in that it deletes the character to the right of the cursor and moves the text beyond that left by one character to fill the gap. If you are at the end of the field or document then the delete key won’t do anything.

It is perfectly legitimate to remove text by either method, depending on where your cursor is and what you are trying to do. You can not, for instance, delete text from a form field with the backspace key if your cursor is at the beginning of the field (because the cursor can’t move further left than the beginning of the field).

Insert and Delete

It is very common to assume that the insert and delete keys are, in some way, opposites of one another. You may think, for instance, that since the delete key deletes text then the insert key may put it back for you. No. There may be an “undo” option available, depending on the program you are using, but that’s another matter. The insert key is another toggle switch. It doesn’t change what you are typing but it changes the way things happen. The two states of the insert switch are:

insert – anything you type will be inserted (added) to what is already there at the current cursor position. If there is already text to the right of the cursor then that text will move rightwards to accommodate the new text as you type it.

overwrite (also known as overtype) – anything you type will overwrite (replace) what is already there at the current cursor position.

If you are typing new content into a form field or a document (say) then it doesn’t matter whether insert is set to insert or overwrite. It does makes a difference if you need to go back and change what’s already there. You can immediately change the state of insert/overwrite by pressing the insert key.

Unfortunately, there isn’t an LED light to indicate the state of the insert switch. A lot of programs, though, will tell you at the bottom of the program window. It will usually be just a single word saying “insert” or “overwrite”. If you can’t find it, look near the bottom of the window and press the insert key a few times and see if anything on the bottom line of the window changes.

Shared Keys

Depending on your keyboard layout, some or all of these keys may share their function with other keys. The key (ha-ha) to getting the function you want is to see if your “function” key (bottom left hand corner of the keyboard) is labelled in a different colour than the normal keys. If it is, then the functions on other keys that match this colour are activated when you hit the key while the function key is depressed. All of this is a lot easier done than said!

For example, on the keyboard displayed here, pressing the numlock key on its own will toggle the state of the numlock switch. If the function key is down when the numlock key is pressed then the result will be the scroll lock function.

See also the blogs on keyboard shortcuts and function keys.

© 2011-2017 David Leonard
Computer Support in London
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