Why do we refer to computers and other machines as being up or down?

Generally when a machine is working we refer to it as "up" and when it's not we say the machine is "down." What is the origin of this?

Solution 1:

The machine is up/down is an instantiation of a Metaphor Theme.

English speakers (like all humans) are oriented vertically with respect to a gravitational field, so the UP/DOWN dimension is significant, and English uses it in a variety of metaphor themes.

These themes include:

• UP is MORE (DOWN is LESS):
  The prices are rising/falling.
  The stock market’s moving up/crashing.
  Turn the volume up/down.

• UP is HAPPY (DOWN is SAD):
  He’s depressed.
  feeling up/down
  What a downer!

• UP is POWERFUL (DOWN is WEAK):
  upper/lower classes
  superior/subordinate
  the highest levels

• UP is ACTIVE (DOWN is PASSIVE):
  The computer is up/down.
  Are you up for some handball?
  Rise to the occasion.

• UP is BETTER (DOWN is WORSE):
  higher/lower animals
  He fell down on the midterm.
  a rise/fall in performance
  aim high
  upwardly-mobile

• UP is ABSTRACT (DOWN is CONCRETE):
  He’s got his head in the clouds.
  He’s got his feet on the ground.
  Come back to earth.
  higher mathematics
  high-level cognitive functions
  low-level details
  new heights of abstraction
  down-to-earth solution

All of these themes are coherent; that is, we tend to think of them in the same ways (e.g, LESS, SAD, WEAK, PASSIVE, and WORSE are all negative evaluations, and vice versa.)

Solution 2:

To shut down has been used to describe machines for a long time, per OED:

Mech. To stop or switch off (a device or machine, esp. an engine); to cause to stop working or running. Also absol.

This use is attested as early as 1895:

1895 When shutting down a machine, the load should first be gradually reduced..by easing down the engine.

• G. W. Lummis-Paterson · Management of Dynamos · 1895.

Why shut down? Probably because of earlier meanings related to shutting down a factory or plant, attested in 1877, which itself seems to derive from the idea of "shutting the doors" of a facility. Shut meaning to close and lock is much older, and shut down implies closing and bolting something to a fixed position, which in machinery is generally the off position.

Another explanation comes from the figurative meaning of up and down with regard to whether something is being powered. This figurative sense seems to apply in an OED definition for "up" that also dates back quite far:

Increased in power, force, strength, or vigour; actually blowing; ready for action. Also (in Computing), in working condition. Frequently in phr. up and running.

In an attestation from 1570, the term referred to wind, a precursor to the figurative use with reference to power described above.

The winde was somwhat vp, and it caused the fire to be ye fiercer.

• John Foxe · The first volume of the ecclesiasticall history contaynyng the actes and monumentes of thynges passed..in this realme · Rev. ed, 1570 (2 vols.).

References to wind appeared to be common with this figurative sense, until a reference to a steamboat in 1848:

A Government steamer..lay in the river, with steam up.

• J. Mitchel · Jail Journal · 1848.

Finally, an attestation is given that refers directly to computers, offered in 1978, though this is by no means the earliest date in which people would have referred to computers that are on as "up.":

British Steel's giant private packet-switched network is up—and running successfully.

• Computing · 1976

So to answer the question directly, the terms seem to go back quite far to figurative meanings related to up, down, shut down, etc. that were used to describe mechanical conditions before computers but also applied as computers became a prevalent technology.

Solution 3:

The word down has been used to describe a state of disablement or non-operation for many centuries before computers, e.g. "Man down", or "He was struck down by his enemy."

Up is then the natural opposite.

But I couldn't say when the word up was first used as the opposite of this sense of down.