Potential source of interrupt aliasing
Wilko Bulte
wb at freebie.xs4all.nl
Mon Apr 11 08:38:03 PDT 2005
On Mon, Apr 11, 2005 at 08:27:47AM -0700, Matthew Dillon wrote..
>
> :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.
The 68k series were much nicer CPUs than Intel built. Too nice apparantly
for IBM to put them into the first PC prototypes.
The rest is history :-(
--
Wilko Bulte wilko at FreeBSD.org
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