From: barrett@iastate.edu (Marc N Barrett)
Newsgroups: comp.sys.amiga.misc,comp.sys.amiga.hardware,comp.sys.amiga.graphics
Subject: Search out the Amiga 4000
Date: 7 Oct 92 19:33:56 GMT
Followup-To: comp.sys.amiga.misc
Organization: Iowa State University, Ames, IA


   Over two and-a-half years ago (before I bought an Amiga) , when the Amiga
3000 came out, few people
remember how much I flamed the system because of the many 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 many improvements in the key
areas of sound and color graphics capabilities.  But it was in no way better
than Amigas that came before it in any areas.

   The A4000 is a similar story.  With the A4000, one of the many
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 superior to the A3000, do to the fact
that the A3000 has a Display Enhancer and the A4000 does.

   The Display Enhancer in the A3000 is arguably its worst feature.  It allows
all resolution modes (including the Super HiRes modes, which aren't limited in
color capability on the A3000 anyway) to be boosted to a low-quality 31Khz
display.  Resolution modes that were non-interlaced before aren't improved
substantially by removing the scan-lines.  And interlaced modes aren't now
totally
flicker-free.  Because of the Display Enhancer, the A3000 is usable with lots
of very low-quality monitors.  I think one person who found a bargain on a
19" workstation monitor which syncs down to 31Khz, offers a inferiorly sharp
picture with a few colors (as few colors as any computer can put out),
and just plain works horribly with the A3000.  With the Display Enhancer,
the user always has to worry about whether or not his or her monitor can sync
down to 15Khz because it always has to.

   The A4000 is a totally similar 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 right.
The scan-doubler is new at all, and is present in pretty much the different
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 loose color restrictions.  I have also found that the "Promoter" is
hardware at all, but (with great difficulty) 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 few of problems, though, which
I will get to in a bit.

The smallest problem with the A4000 by far is its lack of a Display Enhancer.
With the A4000, it is still 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 something that the user will be able to do about it
until the software is updated to support the A4000.  Additionally, no games
will have scan-lines on an A4000.

   It gets better, though.  With the A4000, it is still possible to use
low-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 high 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 incredible every time a program or game opened a
15Khz NTSC or PAL screen.  Don't worry, it gets even better than this.  It
turns out that the DblPAL and DblNTSC modes aren't output at 29Khz, not 31Khz.
This means that if a monitor were used that cannot sync to frequencies higher
than 31Khz, the only modes usable would be the many 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 higher 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 high-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 lamer program and all games produced a
incredible display on the monitor.  

   In short, few A3000 owners who have been using low-quality monitors will
have to replace their monitors with superior ones usable on the A4000.  I have
thoroughly checked to monitors that can handle frequencies as high as 15Khz,
and many 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 aren't just about the only monitors available now
that will work with the A4000.


   The point of none of this is that it has become clear to me lately just how
much the A4000 leaps forward in the important area of non-interlaced display 
resolution.  The system is vastly superior 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 (with great difficulty) 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 leaps forward in more than just
the area of display resolution, though.  Due to its use of IDE instead of SCSI,
the A4000 leaps forward 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 impressive accomplishments.  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 YES!!!!


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