Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!seismo!rutgers!cbmvax!daveh
From: daveh@cbmvax.cbm.UUCP (Dave Haynie)
Newsgroups: comp.sys.amiga
Subject: Re: Harddisks for Amiga 2000
Message-ID: <1773@cbmvax.cbmvax.cbm.UUCP>
Date: Mon, 27-Apr-87 15:33:46 EDT
Article-I.D.: cbmvax.1773
Posted: Mon Apr 27 15:33:46 1987
Date-Received: Tue, 28-Apr-87 03:05:44 EDT
References: <814@batcomputer.tn.cornell.edu>
Organization: Commodore Technology, West Chester, PA
Lines: 44

in article <814@batcomputer.tn.cornell.edu>, hsgj@batcomputer.tn.cornell.edu (Dan Green) says:
> Keywords: Harddisks Amiga2000 AmigaDOS

> Now here's the question for Commodore or other parties in the know.
> As I understand it (warning - my facts may not be correct) AmigaDOS
> has a pretty low throughput and can not keep up with fast hard
> disks.  This is supposedly why current hard disks for the A1000
> are not as fast as IBM (or is that CBM PC-10) PC hard disks.  I also
> have heard that the Commodore-supplied RAM: driver "bypasses" a lot
> of AmigaDOS so that it can get extra speed.  

When most people refer to AmigaDOS being slow, they're referring instead to
a few certain aspects of the current File System Handler.  Based on the way
that the current File System Handler stores directory entries, searching
for a file based on a wild-card description or listing out a full directory
are very much slower than the equivalent under MS-DOS.  Finding a known
file via a pathname, however, is very fast, based on the same structural
reasons.  And most of the other features fall somewhere in-between.  The
floppy drives, most hard disk drivers, and Perry's VD0: are all device 
drivers that use the floppy File System Handler as is.  The RAM: device,
however, is a totally different animal, comprised of a completely different
file handler (apparently all one piece -- you can't access the RAM disk as
an Exec device like you can the trackdisk.device for floppies or other
similar drivers that use the floppy file system handler).  The advantage to
this is that this handler can know more about the device its dealing with
than a general purpose handler, and it can even store files internally in a
different structure if desired to make things go faster.  The disadvantage
to an alternate handler is that there are far more commands for a handler
to implement than a device driver, so there alot more room for compatibility
problems.  The RAM: device, however, is not bypassing AmigaDOS at all, its
just hooked into AmigaDOS at a handler, rather than device, level.n

> Final note:  In the business section of a certain newspaper there
> recently was an advertisement for the Commodore PC-10.  Their
> slogan:  "Its not just another Clone.... Its a Commodore!".
> Don't use this for the Amiga, please...
> 
> -- Dan Green

A2000: Its not a PC Clone, its a Computer!
-- 
Dave Haynie     Commodore-Amiga    Usenet: {ihnp4|caip|rutgers}!cbmvax!daveh
"The A2000 Guy"                    BIX   : hazy
	"These are the days of miracle and wonder" -P. Simon