Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!uunet!van-bc!rsoft!mindlink!a464
From: a464@mindlink.UUCP (Bruce Dawson)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Accelerator and Maximum Fast RAM Query
Message-ID: <1179@mindlink.UUCP>
Date: 21 Feb 90 00:57:57 GMT
Organization: MIND LINK! - British Columbia, Canada
Lines: 30


     The maximum memory that a 68000 based Amiga can have is 10 Megs total.
That's pretty good, considering that the absolute maximum that a 68000 can
address is 16 Megs.

     An '030 based Amiga can, in theory, have 4090 Megs of memory, depending on
whether Commodore has reserved any of that top 4080 Meg memory map.  However,
that depends on your '030 board.  The A2630 has space for 4 Megs, and a
connector for extra 32-bit ram when cards become available.  I don't know what
the equivalent possilibities are for other boards.

     Regardless, you should ditch your 16-bit memory board.  If you're going to
spend $2,000+ on an '030 board, you don't want it slowing down to 68000 speed.
But that's exactly what it will do (usually a bit faster than a 68000, but
sometimes actually slower) if you leave that 16-bit memory in.  So, unless you
want to be paying $600 (assumed amount you could get for selling the 16-bit
memory board) for the privilege of having a slower computer, get rid of it.

     If you set things up to make sure that the 4 Megs of 16 bit RAM is not
used for anything except a disk-cache, then you might get some speed increase
out of it, but not necessarily, since a 1 Meg 32-bit cache might be faster than
a 1 Meg 32-bit and 4 Meg 16-bit cache.

     Plus, the 32 bit RAM, for the 2630 anyway, is not expensive.  I sold my
2-meg board, bought two Megs of ram for my 2630 and came out ahead!

.Bruce Dawson.

     P.S.  Don't forget to get a fat agnus as well, to get rid of that .5 Meg
of slow fast memory.