Single bit, alterable by an application program, read-writeġ6-bit quantity, provided by an I/O system, read-onlyġ6-bit quantity, alterable by an application program, read-write Single bit, provided by an I/O system, read-only The four primary tables are input discretes
The distinction between inputs and outputs, and between bit-addressable and word-addressable data items, do not imply any application behavior.
