From: kcd@cbmvax.commodore.com (Ken Dyke - Amiga Networking)
Newsgroups: comp.sys.amiga.misc
Subject: Re: Problems with the A4000
Date: 12 Sep 92 16:45:41 GMT
Reply-To: kcd@cbmvax.commodore.com (Ken Dyke - Amiga Networking)
Organization: Commodore, West Chester, PA
Keywords: A4000, SCSI, IDE

In article <1992Sep12.083819.17967@news.iastate.edu> barrett@iastate.edu (Marc N Barrett) writes:
>
>   For about a week or so, I've been promising to post my detailed explanation
>of exactly why Commodore's use of a super-cheap IDE HD interface in the A4000
>has very likely pushed the initial list prices higher than what they would have
>been had SCSI been used.

Yes, we've hardly been able to stand the suspense.

>   The problem comes down to the architecture of the A4000 itself.  As has been
>rumored before, several good systems were canceled not long after DevCon '91,
>a year ago.  What has not been said is that these included all of the systems
>that Dave Haynie designed that incorporated the AA chipset.  Indeed, none of
>the new Amiga systems -- including the A4000 -- were designed by him.  They
>were designed in a rush by junior engineers at Commodore.  

I'd be *really* careful Marc about who you call "junior" engineers.  Did you
have anyone at C= in mind? 

Strike one.

>   The whole design of the A4000 can be summed up in a fairly short sentence:
>the A4000 is an A3000 with the CPU moved to a card, the AA chipset kludged in,
>and with the SCSI subsystem replaced with IDE.  I will get back to the issue
>of SCSI & IDE in a minute, but I would first like to explain what other 
>problems this has.  Basically, the A3000 was not designed for the AA chipset.
>The Ramsey and Buster chips in the A3000 were designed for use with the ECS,
>in particular the 2M Agnus chip.  The new Alice chip in the AA chipset -- the
>replacement for Agnus -- can potentially address 4M of chip RAM.  But since

Oh really?  Last time I checked the current rev of Alice could only address
2Mb.

Strike two.

>the Alice chip has been kludged to work with other chips intended for the
>2M Agnus chip, none of the new Amigas can use more than 2M of chip RAM.  The
>use of the A3000 architecture also has other problems, namely the 
>restriction of 16M of fast RAM on the motherboard.  This was not a problem
>several years ago with the A3000 was designed, but 16M is not all that 
>much anymore, with RAM prices at $34/megabyte for 60nS static-column memories.
>
>   OK, I've established that the A4000 is an A3000 with the AA chipset kludged

No, it seems that you've established that you don't know what you're talking
about.

>in.  Now it makes sense to me that it would have cost less in development costs
>to simply leave the A3000's SCSI design there instead of removing it and
>replacing it with something else.  The costs of including SCSI in the A4000,
>then, would have been practically zero in development costs.  
>
>   In addition to the costs involved in removing the SCSI subsystem from the
>A4000's design, though, we also have to consider the costs involved in 
>designing the IDE design.  These costs would have been practically zero if
>the A4000 had simply used the same IDE design as the A600.  The problem is
>that it does not -- the IDE design used in the A4000 is a whole new design.
>The new design was created by Randall Jessup, and includes extra hardware to
>make the IDE interface and HD look somewhat like a SCSI interface and HD to
>Amiga software.  This is a reasonable effort to make the most of a bad
>quite a lot to develop, and would not have been necessary had the A3000's

Strike three, Marc.  The thing Randell Jesup (I''m sure he'd appreciate it
if you could spell his name correctly, BTW) did was to write some special

>   As Dave Haynie and Randall Jessup have already pointed out, IDE -- even the
>new one in the A4000 -- costs next to nothing in terms of manufacturing costs.
>But the development costs involved in creating this IDE design must have been
>very substantial compared to the costs that would have been involved in

IDE is incredibly simple, Marc.  From what I've been told by a number of
the hardware guys, doing an IDE interface is almost a no-brainer in comparison
to a DMA SCSI device. 

>simply carrying over the A3000's existing SCSI design to the A4000.  These
>development costs are still costs, and Commodore is going to want to recoup
>these costs as quickly as possible.  This means boosting the list prices
>to pay the development costs, and then lowering the list prices later as
>soon as these development costs have been payed for.  In the short-term, then,
>the prices on the A4000 and other new systems will be higher than if they

Marc, the A4000 could cost $1500, have 1280x1024 48-bit graphics, have a
32-bit SCSI-2 DMA HD controller, and you'd still bitch about it because
nobody could afford the monitor it would require. 

As always, these are only my personal opinions, and not those of Commodore.

-Ken



-- 
Kenneth Dyke                                  All of the above opinions are my
Commodore-Amiga Networking Group              own and not necessarily those of
email: kcd@cbmvax.commodore.com               my employer.

        "You'll get over it.  If not, you'll learn to live with it."
Newsgroups: comp.sys.amiga.misc,comp.sys.amiga.advocacy