Date: Sun, 30 Nov 1997 22:13:42 GMT From: jak@cetlink.net (John Kelly) To: John-Mark Gurney <gurney_j@resnet.uoregon.edu> Cc: hackers@freebsd.org Subject: Re: 650 UART, SIO driver, 8259 PIC Message-ID: <3481e273.28365467@mail.cetlink.net> In-Reply-To: <19971130124508.58609@hydrogen.nike.efn.org> References: <199711301019.VAA09201@godzilla.zeta.org.au> <19971130030719.29570@hydrogen.nike.efn.org> <3484c18f.19943322@mail.cetlink.net> <19971130124508.58609@hydrogen.nike.efn.org>
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On Sun, 30 Nov 1997 12:45:08 -0800, John-Mark Gurney <gurney_j@efn.org> wrote: >actually, the document only gives examples that have four ports per >interrupt sharing "group"... and this is the case for AST/4 boards too.. >but there is a special option that allows you to put two AST/4 boards >on the same interrupt, and this is then the sharred or common irq Without some extra wires running between the two boards I don't know how they can share an IRQ line. Can you explain how they implement that , hardware wise? >yes, but the thing is that when you have two boards on the same interrupt, >you actually have to poll BOTH status registers of each board to find >out what interrupts to serve Makes sense ... but two boards trying to talk on the same IRQ line, without extra wires, makes no sense to me. John
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