You press a key and a letter shows up. What travels from your finger to the screen, and how fast?

time since key down

0.0 ns · 1 s here = 1 ns

key

B = 01000010

pulse front

in the keyboard · 20.0 cm per ns

wire at the port

0 V · no pulse

processor

0 of 8 bits in: -

screen

0 of 35 dots · (empty)

letters sent

0 bytes · 0 bits

Press the steps in order, or press Auto. Time is slowed down a billion times: 1 second here is 1 nanosecond, a billionth of a second.

Facts from Stanford CS101: Networking (3 volts for a 1, 0 volts for a 0, about 2/3 the speed of light, 1 gigabit = 1 billion bits a second), Bits and Bytes (8 bits make a byte, about one letter), Computer Hardware (a 2 gigahertz processor does 2 billion operations a second), Digital Images (pictures are made of pixels); NIST CODATA (speed of light, 299,792,458 m/s); IETF RFC 20 (ASCII letter codes, 7 bits in a byte with the top bit 0). Example values: the 1 gigabit cable speed, the 20 processor ticks, one pulse per dot of a 5 by 7 letter, and every size and length. Drawn to scale in centimeters (traces drawn wider so they show) with the Anatomy kit (MIT license).