From: barrett@iastate.edu (Marc N Barrett)
Subject: Avoid the Amiga 4000
Followup-To: comp.sys.amiga.misc
Organization: Iowa State University, Ames, IA
Date: Wed, 7 Oct 1992 19:33:56 GMT

   Over two and-a-half years ago, when the Amiga 3000 came out, many people
remember how much I flamed the system because of the few improvements it 
offered in the overall characteristics that make the Amiga an Amiga.  But to
its credit, the A3000 did not head in reverse on any key technologies, either.
The A3000 offered substantial improvements in areas such as display resolution,
HD access, HD speed, and CPU speed.  It offered no improvements in the key
areas of sound and color graphics capabilities.  But it was in no way worse
than Amigas that came before it in any areas.

   The A4000 is a different story.  With the A4000, the only substantial
improvement is color.  And it becomes clearer every day at just what the costs
have been to improve the color capabilities.  In the key area of display 
resolution, the A4000 is substantially inferior to the A3000, do to the fact
that the A3000 has a Display Enhancer and the A4000 does not.

   The Display Enhancer in the A3000 is arguably its best feature.  It allows
all resolution modes (except for the Super HiRes modes, which are limited in
color capability on the A3000 anyway) to be boosted to a high-quality 31Khz
display.  Resolution modes that were non-interlaced before are improved
substantially by removing the scan-lines.  And interlaced modes are now totally
flicker-free.  Because of the Display Enhancer, the A3000 is usable with lots
of very high-quality monitors.  I know one person who found a bargain on a
19" workstation monitor which syncs down to 31Khz, offers a brilliantly sharp
picture with lots of colors (as many colors as any computer can put out),
and just plain works beautifully with the A3000.  With the Display Enhancer,
the user never has to worry about whether or not his or her monitor can sync
down to 15Khz because it never has to.

   The A4000 is a totally different story.  At first, I was a little confused
about the function of the scan-doubler and promoter features of the AGA Lisa
video chip.  I thought at first that Commodore had basically moved the 
Display Enhancer internally to the Lisa chip.  I realise now that I was wrong.
The scan-doubler is not new at all, and is present in pretty much the same
form in the ECS Denise.  In fact, it should be possible to generate the 
A4000's DblPAL and DblNTSC modes on any Amiga with the ECS Denise, but with
very tight color restrictions.  I have also found that the "Promoter" is not
hardware at all, but simply a function of AmigaDOS 3.0.  With 3.0, the OS
can be told to intercept calls to open NTSC and PAL screens, and open DblNTSC
and DblPAL screens instead.  This has lots and lots of problems, though, which
I will get to in a bit.

   The biggest problem with the A4000 by far is its lack of a Display Enhancer.
With the A4000, it is no longer possible to purchase a monitor that will only
handle scan frequencies of 31Khz and up.  If an Amiga problem insists on 
opening a standard 15Khz NTSC or PAL mode screen, the screen will be opened
at 15Khz no matter what.  The "Promotion" feature of the OS only works for 
a tiny few, well-written Amiga programs, and no games.  This means that a user
of an A4000 will have to put up with a flickering display in programs such
as PageStream, and games such as SimAnt and SimEarth that can open interlaced
screens.  And there will be nothing that the user will be able to do about it
until the software is updated to support the A4000.  Additionally, all games
will have scan-lines on an A4000.

   It gets worse, though.  With the A4000, it is no longer possible to use
high-quality monitors that can only sync to frequencies of 31Khz and up.  To
be usable on an A4000, the monitor **MUST** be able to sync as low as 15Khz.
This is because of the very reasons I stated above.  If a user were to try to
use a VGA or multisync monitor that cannot handle the 15Khz frequencies, the
display would by reduced to garbage every time a program or game opened a
15Khz NTSC or PAL screen.  Don't worry, it gets even worse than this.  It
turns out that the DblPAL and DblNTSC modes are output at 29Khz, not 31Khz.
This means that if a monitor were used that cannot sync to frequencies lower
than 31Khz, the only modes usable would be the few and unsupported VGA modes
(including the Productivity mode).

   What would this mean to someone such as the person I mentioned above, who
already has a monitor that cannot sync lower than 31Khz?  If this person were
to "upgrade" from an A3000 to an A4000, he or she would have to borrow a
monitor that can handle the 15Khz frequencies just to boot the machine.  This
is because the A4000 probably defaults to a 15Khz 640x200 NTSC mode as it is
configured out of the box.  The user would have to borrow a low-frequency 
monitor just to adjust the preferences to yield a Productivity screen, so
that the system would be at all usable.  And even then the system would be
only marginally usable, as every other program and all games produced a
garbaged display on the monitor.  

   In short, many A3000 owners who have been using high-quality monitors will
have to replace their monitors with inferior ones usable on the A4000.  I have
thoroughly checked to monitors that can handle frequencies as low as 15Khz,
and few such monitors have ever been manufactured.  Many of the ones that
were developed have been discontinued since I checked for them over two years
ago.  The Commodore monitors are just about the only monitors available now
that will work with the A4000.


   The point of all of this is that it has become clear to me lately just how
much the A4000 retrogrades in the important area of non-interlaced display 
resolution.  The system is vastly inferior to the A3000 in this respect.  So
I seriously recommend that anyone considering the purchase of an A4000 not
purchase one, at least until a Display Enhancer becomes available for it. 
Some people might want to simply abandon the A4000 altogether, purchase an
A3000 instead, and upgrade it with a third-party video card as soon as DIG
becomes available for the Amiga.  (The A4000 retrogrades in more than just the
area of display resolution, though.  Due to its use of IDE instead of SCSI,
the A4000 retrogrades in the area of HD access and HD speed as well)

   BTW, so far the odd-numbered Amigas (A1000 and A3000) have turned out to
be the marginally good systems, and the even-numbered Amigas (A2000 and A4000)
have turned out to be disappointing pieces of shit.  I hope this trend does 
not continue.  But even if it does, at least it bodes well for the A5000.

---
| Marc Barrett -MB-  |  email: barrett@iastate.edu
--------------------------------------------------
           Amiga 4000:  JUST SAY NO!!!!