From owner-freebsd-current@FreeBSD.ORG Mon Apr 11 15:27:48 2005 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 8B68D16A4CE for ; Mon, 11 Apr 2005 15:27:48 +0000 (GMT) Received: from apollo.backplane.com (apollo.backplane.com [216.240.41.2]) by mx1.FreeBSD.org (Postfix) with ESMTP id 43ABF43D49 for ; Mon, 11 Apr 2005 15:27:48 +0000 (GMT) (envelope-from dillon@apollo.backplane.com) Received: from apollo.backplane.com (localhost [127.0.0.1]) j3BFRl0e050814; Mon, 11 Apr 2005 08:27:47 -0700 (PDT) (envelope-from dillon@apollo.backplane.com) Received: (from dillon@localhost) by apollo.backplane.com (8.12.9p2/8.12.9/Submit) id j3BFRlld050811; Mon, 11 Apr 2005 08:27:47 -0700 (PDT) (envelope-from dillon) Date: Mon, 11 Apr 2005 08:27:47 -0700 (PDT) From: Matthew Dillon Message-Id: <200504111527.j3BFRlld050811@apollo.backplane.com> To: Peter Jeremy 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> cc: freebsd-current@freebsd.org Subject: Re: Potential source of interrupt aliasing X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 11 Apr 2005 15:27:48 -0000 :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