ACT apricot - Page 292

CONTROL DEVICE
SYSTEMS INTEREST
The Control Device is essentially a tree-structured set of
jump tables. When program execution is first passed to the
control device entry point, DEV is checked for legality, and
then Jumped upon to the next branch in the tree, where
COM is checked and then jumped upon to the appropriate
configuration procedure,
where DA T is then jumped upon
again passing control to the actual routine required, which
could be anything from setting a flag to configuring the Z80
SIO.