From: daveh@cbmvax.commodore.com (Dave Haynie)
Newsgroups: comp.sys.amiga.advocacy
Subject: Re: Guesses at the new chip set (was Re: MB Interview)
Date: 9 Apr 92 09:08:16 GMT
Article-I.D.: cbmvax.30194
Reply-To: daveh@cbmvax.commodore.com (Dave Haynie)
Organization: Commodore, West Chester, PA

In article <mykes.2127@amiga0.SF-Bay.ORG> mykes@amiga0.SF-Bay.ORG (Mike Schwartz) writes:

>Dave H. has posted more than once that the Chip BUS is 280ns accesses.
>120ns RAM can handle 2x the speed at 140ns.  

Actually, it's 280ns cycle time, not access time.  You generally find, with DRAM, that
cycle time comes out to be around twice the access time.  Thus, you have 150ns or better
for Chip RAM, 80ns for A3000 RAM (which has a 200ns cycle -- 100ns DRAM would work if
you weren't concerned with Burst support).  To simply double the speed of the Chip bus,
you'd probably need 60ns-70ns DRAM.  And more clock granularity -- maybe a 56MHz clock,
to generate the edges necessary to make this work.  That kind of memory is certainly
available, but it's hardly in the el-cheapo category just yet.

>I've been seeing an Indigo a LOT lately.  It does the GUI stuff like
>dragging windows, scrolling text, etc. (not 3d stuff) FASTER than
>the Amiga...

Sure thing, but consider that the Indigo's basic display is only 8-bits deep,
and it has a really fast processor (a good R3000 system is a tad faster than an
'040 system overall, MJCH faster than an '030 system).  If you go to one of the
SGI style 24-bit displays, you probably have a display board with more CPU power
than an A3000 (or, in terms of graphics manipulation prowice, an Indigo).  If it
didn't move 24-bit stuff around well, you might as well write 24-big graphics

>>To be blunt, any bus is going to be a bottleneck.  

Well, given enough imagination and money, any interconnect will eventually
be a bottleneck.  Fortunately, we can restrict our discussion to 
microcomputers, which already wade ankle deep in wasted CPU cycles.  If
you want to speed up your average PC's performance, remove all the PIO
nonsence and put in real I/O sourced DMA like we use in the Amiga.  Once
you have that and still generally run into speed problems, you know your
bus is too slow.

>>Seriously, the ZorroIII architecture is set up so that it could probably be 
>>run at a much faster rate.  I don't know how the actual HARDWARE is set up,
>>however.  

Zorro III could go much faster.  You'll run into interface delays unless 
you're building an ideal Zorro III machine, and after that, you'll hit TTL
practical speed limits more than likely before you run over the Zorro III
specification, at least for best-case burst.

>>Actually, it makes Dave look good.  Everything makes Dave look good, 
>>these days.  

What a nice thing to say.  Or are they still confusing me with Yanni?

>>Wonder why  he doesn't get yanked out from other C= by some other 
>>business????  I wish I knew.  C'mon, Dave, tell us how much Motorola, 
>>Intel, IBM, and Apple have been offering you.  ;)

My first guess is that all of these guys are happy with their engineers,
and too large to notice folks like me.  Also, Intel and Motorola are out
from the get-go; they're chip houses, I'm basically a system designer.
I can't say I never get offers, or that Commodore pays too much, but I
have a question for you that might help give you the answer: You like
Zorro III, I'm proud of it.  Who else would have let me build it?  If
Commodore can start regarding the considerable Engineering talent they
have right now as an asset rather than a payroll, I'll probably be 
content here for years to come.

Of course, my theory of "they're too large" can be disproven in the 
general case.  A few weeks ago I read some article on Bill "the
Billionare" Gates, and it mentioned that MicroSoft now makes more money
than General Motors, and they occasionally find people they want and
pursue them very aggressively.  But they are, of course, software.

>My understanding is that the 16MHz 3000 has a 16MHz fast bus.  Put a
>25MHz CPU in, and it still goes 16MHz on the bus... :(

Maybe.  Your 25MHz coprocessor board can source the motherboard clocks
at 25MHz if its careful.  All A3000 chips are qualified at 25MHz.

>Dave H is not only a fantastic hardware guy, he is also a fantastic
>software guy.  

Damn, any more praise and my head will likely explode.  I do write some
software on occasion.  I look at it kind of like exercise.  I started
out pretty early in electronics, by virture of the fact that my Dad 
(now retired and functioning as a Tennis Bum) was an electrical engineer
(of the old analog school).  He made it real easy to get into electronics,
but along the way I picked up computers, and since programming cost
much less than bit twiddling, I got into it as a teenager (along with
canoeing, Judo, girls, swimming, scuba, photography, etc. -- I wasn't
one of these one sided wiz kids).  In college, I majored in EE, but
eventually picked up a double degree in EE and Math/CS.  So I find I
need to write software on occasion to keep good at it.  Plus, after a
long day in the lab, the last thing I'm going to do is go home and
hack more hardware.  My shop here is full of sawdust, not wires...
As Heinlein said, "specialization is for insects".

>According to my understanding of what Dave H has written, the Amiga already
>does 35ns pixels.

Indeed.  ECS does 35ns pixels, both "Productivity" and "SuperHires" are
35ns pixel modes.

-- 
Dave Haynie Commodore-Amiga (Amiga 3000) "The Crew That Never Rests"
   {uunet|pyramid|rutgers}!cbmvax!daveh      BIX: hazy
   "We can't be silent, because they might be giants" - The Might Be Giants
 
Newsgroups: comp.sys.amiga.advocacy