How does a keyboard work?

Question

I am talking in terms of the good old DOS mode.

Can someone kindly tell me how does a keyboard work? For example, when I press the key "A", what really happens? What cause the letter "A" to appear on screen?

Also, if I type a word say "dir" in DOS prompt, what cause the letters to be arranged neatly in a row? Is it the DOS or is it the CPU? Why doesn't the letters appear randomly all over the black screen? Why are letters arranged in rows on the black screen?

Also, after typing the word "dir" and I press enter, how does the CPU accept the word typed?

Lastly, if I want to add my own character on the keyboard to be used, what do I need to update? The keyboard circuit only or the CPU also?

How does a keyboard work? Does anyone have any reference?

Answer 1

go on a computer course you stupid idiot

Answer 2

When a key is pressed, it pushes down on a rubber dome sitting beneath the key. A conductive contact on the underside of the dome touches (and hence connects) a pair of conductive lines on the circuit below.
This bridges the gap between them and allows current to flow (i.e. the circuit goes from open to closed), changing the signal strength.
A scanning signal is emitted by the chip along the pairs of lines to all the keys. When the signal in one pair becomes different, the chip generates a "make code" corresponding to the key connected to that pair of lines.
The code generated is sent to the computer either via a keyboard cable (using on-off electrical pulses to represent bits) or over a wireless connection.
A chip inside the computer receives the signal bits and decodes them into the appropriate keypress. The computer then decides what to do on the basis of the key pressed (e.g. display a character on the screen, or perform some action).

Answer 3

You only have asked a half dozen quests at once but, the bios controls the inputs and outputs of the system including the keyboard. Its done in low level machine code. To explain it in detail it would take me too much time! If ya wanna pay me 50 bucks an hour I will be glad to help!

Answer 4

dude, i think u shud ve put them as different quests...
anyways, i cant type everything here but still lemme be quick enuf to tell u some basic things...

the ASCII code for a caps letter 'A' is 65.. so as soon as u type the letter 'A', which is a high level language (HLL) and that which can be understood by you, there is something called as compiler/ assembly lever language (ALL) which translates this code into binary digits (bits).. i hope u know how to convert a no 4m a decimal system to binary system (0s and 1s)... so when its translated into low level language (LLL) by the compiler, the machine processes it... (0 means off n 1 means on.. digital theory)... so after its processed, it gets back to compiler which again translates the low level language into high level language... output is displayed using output devices, say monitor...

if u wanna know more abt conversion, i wud be glad to tell u...

i think u got atleast fair idea now...


if u wanna know more, u can log in to http://www.howstuffworks.com

Answer 5

If you had asked two years ago when I was taking a digital electronics course I could have given you a two page explanation from memory, but that's a little fuzzy now so I'll let the experts handle it. Howstuffworks.com is a great website for questions like that, and they usually have a brief, easy to understand explanation as well as a detailed, technical one.

Answer 6

Yeah Right, How long have you got?
Do a web search and read some gumph.

Answer 7

just start typing u will know how it works

Answer 8

You have too much time on yer hands. get out more you crack head