From: jms@tardis.Tymnet.COM (Joe Smith)
Newsgroups: comp.sys.amiga.graphics,comp.sys.amiga.misc
Subject: Commodore announces A4000 with AGA (AA) graphics chips
Summary: World of Commodore/Amiga in Pasadena
Date: 15 Sep 92 04:42:34 GMT
Followup-To: comp.sys.amiga.graphics
Organization: BT Tymnet, San Jose, CA

I just got back from the World of Commodore/Amiga show that was in Pasadena
September 11-13.  Without bothering to read what's been posted so far, here's
my report.

The A600 is for real and is for sale, as is the A570 CD-ROM drive for the
A500.  Pictures of the A600 are in both Amiga World and Amazing Computing.
Imagine taking a saw to a regular Amiga keyboard and cutting off everything
to the right of the left cursor key.  That is, chop the DEL key in half,
get rid of the up, down and right cursor keys, the HELP key, and the numeric
keypad.  The cursor keys are under the shift key on the A600 and the HELP
key is next to F10.  The A600 is designed to be less expensive to
manufacture, and is not expandable the same was as the A500.  It is best
suited for the low-end users who do not plan to add anything to their
machine other than an external floppy and a second meg of internal memory.

The A570 CD-ROM drive for the A500 is $599, including installation.  This
option has to be installed by a dealer because the A500 motherboard has to be
brought up to rev before it can reliably use the CD-ROM.

People who buy a new A3000 will get a CDTV unit free.  Existing owners can
a CDTV unit for $599.  The unit comes with a specially modified cable for
connecting the CDTV to your Amiga's parallel port and software for running
ParNet software between them.  The ParNet software for your existing Amiga
comes on a 3.5-inch floppy, the software that runs on the CDTV is on the
Fred Fish CD-ROM collection that comes with the package.  With ParNet
running, the CDTV can access your Amiga's floppies and your Amiga can access
all the files on the CD-ROM.

For all systems other than the A500, Commodore's official policy is "if you
want a CD-ROM for your system with our name on it, pay $600 for our CD-ROM
package with comes with another Amiga CPU at no extra cost."

	===========================================================

The A4000 was shown, but it is not in full production yet.  It comes with a
25Mhz 68040 (which is on a replaceable CPU board in case something better
comes along), 2M Chip ram, and up to 16M of fast ram in industry standard
SIMMS on the motherboard.  AmigaDOS-3.0 is in ROM and includes the CrossDos
library for reading and writing MS-DOS floppies directly.  No display
enhancer; the flicker-fixer function is done under software control by the
AGA chips.  One Zorro-III Amiga expansion slot inline with the enhanced
video slot and three Zorro-III slots inline with PC/AT slots (just like the
A3000, except that the video slot is on the bottom instead of the top of the
daughter board).  The 3.5-inch floppy stores 880K or 1.76M in Amiga format,
720K or 1.44M in MS-DOS format.  (The drive spins at 1/2 speed for the
high-density modes so as to not exceed Paula's I/O rate.)  Four 3.5-inch
bays; 2 in back for hard disks, 2 in front for floppies or Floptical (21
meg) disks.  One 5.25-inch bay in front, suitable for a CD-ROM drive
whenever it comes out.  Same 4-channel 8-bit sound; the Paula chip has not
been upgraded yet.  NTSC/PAL/VGA 24-bit video on the 23-pin RGB port.

The big news is the AGA (Advanced Graphics Architecture (tm)) chips.  (The
term "AA" was an internal code name; the offical designation is "AGA" now.)
"Alice" replaces "Agnus" as the DMA controller, "Lisa" replaces "Denise" as
the color video chip.  All the registers and internal data paths are now 32
bits wide.  There are now 256 color registers, and they store 25 bits - 8
bits red, 8 bits green, 8 bits blue, and 1 bit of transparency to drive the
COLOR0 signal for genlocks.  (A one-bit alpha channel.)

They've quadrupled the rate at which the custom chips can access graphics
RAM.  One factor-of-2 speedup is by accessing RAM 32-bits at a time instead
of 16-bits at a time like the ECS and previous chips did.  The second
speadup is by reading two 32-bit longwords on each memory cycle.  (The CAS
line is strobed twice per each stobe of the RAS line.)  This means 8 bit
planes can be read IN ALL GRAPHICS RESOLUTIONS!!!!  256 colors out of a
palette of 16 million.  Eight-bit HAM!

Let's compare this to the ECS graphics modes:

Lo-res: 320x200 and 320x400 (NTSC) or 320x256 and 320x512 (PAL)
  32-color (5 bitplanes), uses up 62% chip bandwidth, no color restrictions.
  Extra-Halfbrite (6 bitplanes), uses 75% bandwidth, colors 32-62 from 0-31.
  HAM (Hold And Modify) (6 bitplanes), 75%, 16 base colors, 4096 derived.

Hi-res: 640x200 and 640x400 (NTSC) or 640x256 and 640x512 (PAL)
  16-color (4 bitplanes), uses up 100% chip bandwidth, no color restrictions.
  (It is possible to run a 16-color Workbench, but not adviseable.  During
  the active part of each scan line, the graphics chips lock out the CPU and
  the blitter.  It is better to run an 8-color Workbench (which uses up only
  75% of the memory accesses) or a 4-color Workbench.)

Super-Hires: 1280x200 and 1280x400 (NTSC) or 1280x256 and 1280x512 (PAL)
  4-color (2 bitplanes), uses up 100% chip bandwidth, palette of 64 colors.
  (The bits are coming out so fast (35 nanosecond resolution) that Denise
  can't modulate more than 2 bits each of red, blue, and green.  To get any
  work done with the display is active, the graphics has to be reduced to a
  single bitplane; only 2 colors.)

Productivity: 640x480 at 31KHz horizontal, noninterlaced 60Hz (VGA)
  Same restrictions as Super-Hires (4 colors out of a palette of 64), but
  can drive a VGA monitor directly without a scan doubler or flicker fixer.

The new AGA graphics modes are:

Productivity:                640x480 VGA, 256 colors or HAM-8 (100%)
72Hz vertical/31KHz horizontal:  640x480, 256 colors or HAM-8 (100%)
Super-Hires: 1280x400 NTSC, 1280x512 PAL, 256 colors or HAM-8 (100%)
Hires:        640x400 NTSC,  640x512 PAL, 256 colors or HAM-8  (50%)
Lores:        320x400 NTSC,  320x512 PAL, 256 colors or HAM-8  (25%)

You can run Workbench in 256 color mode, where windows can have up to 256
colors out of a palette of 16 million colors.  (This reduced the need to
open a custom screen just to get more colors.)  Or you can switch to HAM-8
mode, where 64 of the color registers are directly accessable.  By holding
the previous color and adjusting the high-order 6 bits of R, G, or B, HAM-8
can display 262144 (256K) different colors.  With 64 base colors, the "HAM
fringing" effect is a lost less noticable.

	=============================================================

Obvious question: When can I add the AGA chips to my A2000 or A3000?
Disappointing answer: Never.

In order to make the A2000 or A3000 do 32-bit into and between the graphics
chips, you would have to locate the lines that connect the graphics chips
together (16 data bits and 8 bits of register address), rip them out, and
wire in 32+N new traces.  I.e. a MAJOR redesign of the motherboard.  The
replacements for Agnus, Denise, and all the chip RAM would have to go onto a
separate board, sort of like the Rejuvenator project for the A1000.  But
this is not something Commodore would do.  It would have to be a 3rd party
solution, if ever.

-- 
Joe Smith (408)922-6220     BTNA GNS Major Programs, TYMNET Global Network
<jms@tardis.tymnet.com>     P.O. Box 49019, MS-C51, San Jose, CA 95161-9019
CA license plate: "POPJ P,"    Married to the LB, Quantum Leap's #1 net.fan
PDP-10, 36-bits forever!    Humorous disclaimer: "My Amiga 3000 speaks for me."
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