vt. To transfer data or (esp.) code from a larger `host'
system (esp. a mainframe
) over a digital comm link to a smaller
`client' system, esp. a microcomputer or specialized peripheral.
However, note that ground-to-space communications has its own usage
rule for this term. Space-to-earth transmission is always download
and the reverse upload regardless of the relative size of the
computers involved. So far the in-space machines have invariably
been smaller; thus the upload/download distinction has been
reversed from its usual sense.