Re: Memory Map

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#13

From: Mark Huth
Date: Tue, 13 Jun 1989 01:32

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In article <109194@sun.Eng.Sun.COM> cmcmanis@sun.UUCP (Chuck McManis) writes:
>space. Of course due to the way the 68000 resets, ROM has to be located
>at $FFFFFF, but can extend "down" toward 0 an arbitrary distance, 256K
>in the case of the current Amigas, probably 512K in a future Amiga. (
Sorry Chuck, the 680xx all get their reset vectors from logical
address 0 - you have to have special circuitry to decode the first
accesses after reset in the Amiga ROM space.  The choice of ROM
location has nothing to do with the 680xx reset sequence.

After reset, the 680xx fetches a longword from location 0 in the
supervisor program space for use as the system stack pointer, and then
fetches a longword from location 4 to load the program counter.  It
then begins execution in supervisor mode at the location specified by
the PC load.

Mark Huth

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Path: arc1-ca.pugleaf.net!utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!apple!bionet!ames!ncar!noao!asuvax!behemoth!mph

References: <17184@louie.udel.EDU> <109194@sun.Eng.Sun.COM>

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Path: arc1-ca.pugleaf.net!utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!apple!bionet!ames!ncar!noao!asuvax!behemoth!mph
From: mph@behemoth.phx.mcd.mot.com (Mark Huth)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Memory Map
Message-ID: <11068@behemoth.phx.mcd.mot.com>
Date: 13 Jun 89 01:32:19 GMT
References: <17184@louie.udel.EDU> <109194@sun.Eng.Sun.COM>
Reply-To: mph@behemoth.UUCP (Mark Huth)
Distribution: usa
Organization: Motorola Microcomputer Division, Tempe, Az.
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