Path: utzoo!attcan!uunet!ncrlnk!ncrcae!ece-csc!mcnc!rti!sunpix!matthew
From: matthew@sunpix.UUCP ( Sun NCAA)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Usable I/O Address range on the PC bus ...
Keywords: Think of it this way...
Message-ID: <283@greens.UUCP>
Date: 23 Nov 88 17:16:56 GMT
Organization: Sun Microsystems, Research Triangle Park, NC
Lines: 22


You've got to think of it this way. Use the address bits A0 thru A9 to
select where in the 1K of IBM PC/XT/AT I/O space where you want your
board to be mapped to. Then use the address bits A10 thru A15 to decode
to one of 64 "ghosted" addresses. 





         A15 A14 A13 A12 A11 A10   A9 A8 A7 A6 A5 A4 A3 A2 A1 A0
        \__________  ___________/ \_____________  ______________/
                   \/                           \/

             Used to decode 64           Used to assign PC/XT/AT
             "ghosted" addresses         compatible address.
                                         (could be switch selectable)

-- 
Matthew Lee Stier     (919) 469-8300|
Sun Microsystems ---  RTP, NC  27560|          "Wisconsin   Escapee"
uucp: {sun, rti}!sunpix!matthew     |