Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!zaphod.mps.ohio-state.edu!unix.cis.pitt.edu!dsinc!bagate!cbmvax!daveh
From: daveh@cbmvax.commodore.com (Dave Haynie)
Newsgroups: comp.sys.amiga.advocacy
Subject: Re: The Amiga's Future
Message-ID: <22372@cbmvax.commodore.com>
Date: 12 Jun 91 20:21:58 GMT
References: <#g1H3+$o@cs.psu.edu> <12901@uwm.edu> <22308@cbmvax.commodore.com> <1991Jun11.134256.9465@cs.mcgill.ca>
Reply-To: daveh@cbmvax.commodore.com (Dave Haynie)
Organization: Commodore, West Chester, PA
Lines: 44

In article <1991Jun11.134256.9465@cs.mcgill.ca> genius@cs.mcgill.ca (Michel NGUYEN) writes:

>>You're wrong.  There's no standard for motherboard RAM amoung IBM compatibles.  
>>...

>All (that I know of) of 386 ISA based have 32 bit memory bus. 

That's exactly what I have said.  However, a 32 bit bus doesn't imply either
standardization or expandability.  

>Many PC clones manufacturers (Compaq, ALR, ...) have systems with 
>128MB on the motherboard ALONE. Of course extra-memory can be added on
>daughterbards. 

Assuming there are daughterboards.  There very well may not be 32 bit daughter
boards, other than perhaps the ISA or EISA bus, neither of which is ideal for
memory.  Some have all their expected memory on the motherboard, via SIMM
modules.  Some have a proprietary 32 bit slot for memory, in addition to a
little on the motherboard.  

What's annoying about arguing PCs is, everything exists.  When people argue
features, they point to $10,000 Compaqs.  When they argue price, they point
to $3,000 Taiwan specials. 

>I am talking about EISA systems. 

As I mentioned, you don't really want memory on the EISA bus.  EISA is 
reasonably quick with burst mode (in the Zorro III category), but it's not
so hot at single cycle accesses.  In other words, it's optimized for I/O.
There is no standard memory bus for PCs.  Actually, a year ago two companies
were working on one.  One company, S3, dropped the project, I haven't heard
much lately from the other one.

>Theorically, the 386 and 486 can have more than 16000 segments of
>4GB each segment (48 bits). 

Sure they can.  But nobody cares about segments.  The physical addressing
limits are the same as for most 32 bit processors -- 4GB.  All the PC Clone
'386/'486 UNIXs use demand paging, not segments (in fact, the design of a
'386 BSD UNIX has been discussed over several recent issues of Dr. Dobb's).
-- 
Dave Haynie Commodore-Amiga (Amiga 3000) "The Crew That Never Rests"
   {uunet|pyramid|rutgers}!cbmvax!daveh      PLINK: hazy     BIX: hazy
	"This is my mistake.  Let me make it good." -R.E.M.