console.read — Default Console input stream
Determines where console input will come from. See console.write for details on setting the write stream.
There are three console drivers available on every
platform, the null driver which
produces no input so no buttons can be pressed, the
all-rd driver which accepts input from
any console driver capable of producing it and the
serial driver which accepts input from
the console serial port (typically the first serial port on a
system).
The default, where no nvram variable is set, on all
platforms since ABLE version 1.79 is the
all-rd target.