From: spence@cbmvax.commodore.com (Spencer Shanson)
Newsgroups: comp.sys.amiga.hardware
Subject: AA Features
Date: 14 Sep 92 21:43:36 GMT
Organization: Commodore, West Chester, PA

Now that AA (AGA) has been finally released, and to quash any future questions
as to what AA can and cannot do, here is a list of display modes that I compiled
when I first started working on the AA project.

This is the definitive guide! There is no more and no less information to be
had with regards AA.

All AA features can be used through the appropriate calls provided by the
operating sysyem (AmigaDOS Release 3, kickstart V39). All other methods of
enabling features (such as writing directly to the hardware, poking copper lists
etc) will *NOT* be supported in future machines.

                           YOU HAVE BEEN WARNED!

You want a feature, use the OS. That's what it's for.


NB -
1 colour clock = 280ns
1 Lores pixel = 140ns (2 per colour clock)
1 Hires pixel = 70ns (4 per colour clock)
1 SuperHires pixel = 35ns (8 per colour clock)
1 VGA pixel = 35ns (8 per colour clock)

                           NEW AA DISPLAY MODES
                           ====================


We now have a palette of 2^24 colours. Each colour has 8 bits each of Red, Green
and Blue (hence 24 bits of colour), + 1 genlock bit.


LORES
-----

6 Bitplane (non HAM, non EHB)	64 colours				!
7 Bitplane			128 colours				!
8 Bitplane			256 colours				!
8 Bitplane HAM			Any of 2^24 colours			!
Dual Playfield, Max 4 Bitplanes per playfield				!
			16 colours per playfield. The bank of 16 colours
			in the 256 colour palette is selectable per
			playfield.



HIRES
-----

5 Bitplanes			32 colours				@
6 Bitplanes			64 colours				@
7 Bitplanes			128 colours				@
8 Bitplanes			256 colours				@
6 Bitplanes EHB			32 * 2 colours				@
6 Bitplanes HAM			4096 colours				@
8 Bitplanes HAM			any of 2^24 colours			@
Dual Playfield, Max 4 Bitplanes per playfield				! or @
			16 colours per playfield. The bank of 16 colours
			in the 256 colour palette is selectable per
			playfield.

SUPERHIRES
----------

1 or 2 bitplanes, as ECS, bit with no colour fudging			!
3 Bitplanes				8 colours			@
4 Bitplanes			16 colours				@
5 Bitplanes			32 colours				$
6 Bitplanes			64 colours				$
7 Bitplanes			128 colours				$
8 Bitplanes			256 colours				$
6 Bitplanes EHB			32 * 2 colours				$
6 Bitplanes HAM			4096 colours				$
8 Bitplanes HAM			any of 2^24 colours			$
Dual Playfield, Max 4 Bitplanes per playfield				@ or $
			16 colours per playfield. The bank of 16 colours
			in the 256 colour palette is selectable per
			playfield.

All playfield scrolling is now in 35ns increments, range 0-63.
Pre AA scrolling was in 140ns increments, range 0-15

VGA
---

1 or 2 bitplanes, as ECS, bit with no colour fudging			!
3 Bitplanes			8 colours				@
4 Bitplanes			16 colours				@
5 Bitplanes			32 colours				$
6 Bitplanes			64 colours				$
7 Bitplanes			128 colours				$
8 Bitplanes			256 colours				$
6 Bitplanes EHB			32 * 2 colours				$
6 Bitplanes HAM			4096 colours				$
8 Bitplanes HAM			any of 2^24 colours			$
Dual Playfield, Max 4 Bitplanes per playfield				@ or $
			16 colours per playfield. The bank of 16 colours
			in the 256 colour palette is selectable per
			playfield.

KEY:
! needs 1x Bandwidth
@ needs 2x Bandwidth
$ needs 4x Bandwidth

NB - the A4000 is configured for 4x bandwidth.

The Euro72 and Super72 modes are variations of the VGA modes (just different
resolutions and refresh rates).

There is also a "Scan Doubling" feature. This allows each scan line to be shown
twice. The purpose of this is to enable a software work-around to replace the
display enhancer found on the A3000. With the "promotion" feature enabled, NTSC
and PAL displays are "promoted" to a flicker-free version defined in the
DblNTSC/DblPAL monitors. These two monitors are also variations of the VGA
monitor, but designed to resemble as closely as possible the NTSC and PAL
dimensions, but at twice the refresh rate. In other words, the DblNTSC monitor
will provide 640x400 dimension, non-laced, at 60Hz refresh, the DblPAL will
provide 640x512 non laced at 50Hz. Non-laced NTSC/PAL screens (such as 640x200)
will also be promoted, but will take up as much space on the screen as the
640x400 will through scan-doubling.

Of course, all the ECS genlocking features have been carried through to AA.

SPRITES
=======

Prior to AA, sprites were always displayed with 140ns pixels, except on
SuperHires or VGA screens, where sprite pixels were 70ns long.

With AA, all sprites can now be displayed in either:

1) ECS mode															!
2) 140ns (this is not the same as ECS mode - see above!)									!
3) 70ns																@
4) 35ns																$

on any display resolution. eg 35ns sprites on a lores screen, or 140ns sprites
on a superhires screen.

Sprites can be positioned to 35ns resolution.

Sprites are either 16, 32, or 64 bits wide.

Sprites can be attached in any mode (could not attach sprites in the new
ECS modes).

Sprite resolution affects all the sprites, in other words you cannot have sprite
3 64 bits wide with 70ns pixels, and sprite 4 32 bits wide with 35ns pixels.

Even numbered and odd numbered sprites can select any bank of 16 colours from the
256 colour palette for the sprite colours.

Sprites can also be scandoubled (to maintain aspect ratio).
-- 
---------------------------------------------------------------------------
Spencer Shanson - Amiga Software Engineer     | email: spence@commodore.COM
                                              | or uunet!cbmvax!spence
All opinions expressed are my own, and do not | Bix: sshanson
(necessarily) represent those of Commodore.   | "Render? I hardly even
                                              | know her!"