Most common: 104 key Windows keyboard.
Notebooks have fewer keys (mine has 84)---usually no numeric keypad.
Apple keyboards fewer keys as well
Variety of other keyboards available.
Switches, connected to a microprocessor, one for each key.
Key "bridges" circuit
microprocessor observes these circuits and compares to "character map", also for combinations
Computer also has a character map
typematics: press key longer: what happens?
provides "feel" of a typewriter. Clicks, keys jump back, ...
small amount of power comes from the computer to the keyboard
letter information is sent from the keyboard to the computer.
Sent is a string of 0s and 1s.
Characters are encoded as Bytes
Everything in computers is encoded as 1s or 0s, either
through the cable or in storage.
Bit: either a "0" or a "1".
Byte: A package of 8 bits.
How many thing can you encode using 8 bits?
(Extended) Ascii code: Encoding of characters using a byte (sequence of 8 bits). For instance "A" is encoded as "65", "a" as "97".
Erich Prisner, August 2003