System Interrupts; Table 6-4: Interrupt Level Assignment - Datatech Enterprises Apex 386SX/20 User Manual

The 8254-2 timer/counter is treated by system programs as an arran-
gement of four programmable external I/O ports. Three are treated as
counters; the fourth is a control register for mode programming.

System interrupts

Si xteen levels of system interrupts are provided by the 80386SX NMI
d two interrupt controller chips. The following shows the
an
8259A
in terrupt-level assignments' decreasing priority:
T able 6-4: Interrupt Level Assignment
Chapter 6: Appendix
19