Electronic Computing

Front

Electrically-controlled mechanical switches in room-sized computers

Back

Mechanical relays

Front

Relay analogy: control wire = ?

Back

faucet handle

Front

Relay flick rate in the 1940s

Back

50 times per second

Front

Harvard Mark I: Complex operations time

Back

over a minute

Front

Harvard Mark I faulty relay replacement

Back

1 per day

Front

Bug found in Harvard Mark II (1947)

Back

Moth

Front

"Bugs in computers" quote

Back

Grace Hopper

Front

First device developed by John Ambrose Fleming in 1904

Back

Vacuum tube

Front

One-way current flow component

Back

Diode

Front

Lee de Forest's 1906 addition to Fleming valve

Back

Third 'control' electrode