From: daveh@cbmvax.commodore.com (Dave Haynie)
Newsgroups: comp.sys.amiga.misc
Subject: Re: Avoid the Amiga 4000
Date: 13 Oct 92 00:17:35 GMT
Reply-To: daveh@cbmvax.commodore.com (Dave Haynie)
Organization: Commodore, West Chester, PA

In article <1992Oct7.193356.6639@news.iastate.edu> barrett@iastate.edu (Marc N Barrett) writes:

>   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
>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.  

News flash: you're still confused.  It's your only career.

The Lisa's scan doubler function allows it to send the same scan line out twice,
in order to allows a display to use twice the number of lines it was designed
for.  This allows the OS to promote a 640x200 or 640x256 screen to a 640x400 or
640x512 resolution while maintaining the proper aspect ratio.  The ECS chips
could not do this, DblNTSC and DblPAL are impossible on ECS.

>I have also found that the "Promoter" is not hardware at all, but simply a 
>function of AmigaDOS 3.0.  

Yeah, like Colombus "found" America.  The promotion mechanism, with respect to
ECS non-interlaced screens, relies on this line-doubling hardware.  It also
relies on the OS setting up the proper display.

>With 3.0, the OS can be told to intercept calls to open NTSC and PAL screens, 

The OS is what opens screens.  It's hardly "intercepting" calls. 

>   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.  

That's a problem with the program, not the A4000.  It's much like a PC program
that insists on opening a display in Hercules or EGA mode.  My recommendation
is that you throw such programs out (well, not you Marc, since you don't have
an A4000).

>The "Promotion" feature of the OS only works for a tiny few, well-written 
>Amiga programs, and no games.  

Actually, it works for quite a bit of stuff.  Of course, never having owned
such a machine or any recent software, you won't know anything about this.  It
even handles some games properly.  In fact, all the games that were written
to the OS Amiga specifications.  It's much like the set of Mac games that run
on the Quadra.

>This means that a user of an A4000 will have to put up with a flickering 
>display in programs such as PageStream, 

PageStream works great.  Open it on Workbench, version 2.2 even knows about the 
8-bit palette if you have one, and it works fine in Moniterm (1024x800) or 
SUPER72 overscanned (890x620) resolutions.
 
>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.  

Other people might want to stick with their A500 and just badmouth stuff they're
too cheap to buy or too ignorant to understand.  Naaa, couldn't happen...

-- 
Dave Haynie Commodore-Amiga (Cool Advanced High-End Systems You Can't See Yet)
 "The Crew That Never Rests"  {uunet|pyramid|rutgers}!cbmvax!daveh   BIX: hazy
              "I got a pocket full of kryptonite" -Spin Doctors