Potential source of interrupt aliasing

[Matthew Dillon]

:Both the 8080 and 8085 supported vectored interrupts to a limited
:extent.  The 6800 and 6809 don't support vectored interrupts.  The
:Z-80, 68000 and 8086 all fully support vectored interrupts.  But the
:Z-80 and 68000 both need the designer to (exclusively) use the Z-80 or
:68000 peripheral chips in order to take advantage of their vectored
:interrupts.  Using a separate interrupt controller means that you can
:use bog-standard peripherals that just have INTR outputs.
:
:It's a pity that the modern PC is hamstrung by design decisions made
:over 25 years ago.
:
:-- 
:Peter Jeremy

    The 68000 had a nice system, and you didn't have to use 68000 peripheral
    chips to take advantage of it.  You could a auto-vector the IACK cycle
    for certain SPLs (the poor man's solution) or, even better, you could map
    RAM into the autovector space (basically ignore the FC lines) and then
    use a simple 8:3 (or other) selector to generate the vector for some or
    the SPLs for chips that could not generate one themselves.

    It's sad to know that a single 20 year + old $0.10 14 pin chip can outdo
    an APIC.

					-Matt
					Matthew Dillon 
					<dillon at backplane.com>