Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!sun-barr!newstop!sun!pepper!cmcmanis
From: cmcmanis%pepper@Sun.COM (Chuck McManis)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Memory Map
Message-ID: <109194@sun.Eng.Sun.COM>
Date: 9 Jun 89 18:38:23 GMT
References: <17184@louie.udel.EDU>
Sender: news@sun.Eng.Sun.COM
Reply-To: cmcmanis@sun.UUCP (Chuck McManis)
Distribution: usa
Organization: Sun Microsystems, Mountain View
Lines: 31

In article <17184@louie.udel.EDU> new@udel.EDU (Darren New) writes:
>A while back, somebody asked about the memory map of the amiga and
>was answered by "ExecBase is a $4". Although correct, this is not
>what I'm asking. I'm just curious about the actual memory mapping
>in the Amiga. Where IS chip ram? What is $c00000 ram? Where is FAST ram?
>where do devices configure? Where is the ROM/WCS//re-live-boot-rom-on A1000s?
>And so on...     --- Darren

The problem is that there isn't any answer for this that is correct 
other than "Ask Exec" which is what you can do by getting the address
of ExecBase in $4. On current Amiga's $000000 - $1fffff is reserved for
chip ram, but there are recognized problems with using the lower 2 meg
of ram space for this purpose, (interrupt vectors get stuck there on
68000 machines for one.) $200000 - $B00000 is normally fast ram, but
here again so is everything over 16 meg currently if you have an '020.
The custom chips have registers currently located at $DFF000 - $DFFFFF
but there is no reason that can't change. And devices, well when they
autoconig they are told what addresses they should reside at and I
believe that this means they will exist somewhere in the $E00000 address
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. (
Especially now that Intel is selling a 256K X 16 EPROM.) All of this
information is contained in the Hardware manual, but the up to date 
information is always contained in Exec's lists. 


--Chuck McManis
uucp: {anywhere}!sun!cmcmanis   BIX: cmcmanis  ARPAnet: cmcmanis@sun.com
These opinions are my own and no one elses, but you knew that didn't you.
"A most excellent barbarian ... Genghis Kahn!"