Reflexes are machine responses to surprises. In unix this is typically a
"bottom end" of a "device driver". Reflexes can be callee-saves, saving a
state-switch on the requisite trap to the system.

"discern" is the general wallclock reflex, and may do any or all of the 3
subresponses for second, subsecond or churchbell (daily, alarm).

The cPC harmony engine goes in the subsecond response probably. Or IRQ0,
PIT0.

