Date: Mon, 11 Apr 2005 17:37:58 +0200 From: Wilko Bulte <wb@freebie.xs4all.nl> To: Matthew Dillon <dillon@apollo.backplane.com> Cc: freebsd-current@freebsd.org Subject: Re: Potential source of interrupt aliasing Message-ID: <20050411153758.GA57182@freebie.xs4all.nl> In-Reply-To: <200504111527.j3BFRlld050811@apollo.backplane.com> References: <20050406233405.O47071@carver.gumbysoft.com> <200504081656.51917.jhb@FreeBSD.org> <20050410152946.W82708@carver.gumbysoft.com> <20050410172818.D82708@carver.gumbysoft.com> <200504110231.j3B2VOYr047361@apollo.backplane.com> <20050411083006.GJ89047@cirb503493.alcatel.com.au> <200504111527.j3BFRlld050811@apollo.backplane.com>
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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@FreeBSD.org
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