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THE AMIGA 4000
by Eddy Carroll, October 1992

In September 1991 at the European Developers Conference in Milan, developers were treated to a first look at the new Amiga graphics shipset, then known as the AA Chipset (AA standing for Advanced Amiga). Now, just over a year later, the first machines featuring that new chipset have arrived: the Amiga 1200 (see elsewhere) and Amiga 4000.
   For some months, I had been trying to figure out a way to convince myself that I needed a 68040 card for my A3000 to give it a speed boost. Now, for little more than the price of one of those cards, I could get a brand new computer. I was sold. Two other CUGI members, Leon Hurst and Rocco Matassa also fell under the A4000's spell and we placed the three orders together. The machines arrived on 13 October.

Let's Get Physical
Physically, the A4000 is somewhere between the sleek lines of the A3000 and the ugly utility of the A2000. Its dimensions are a compact 15" x 15" x 5" and it is enclosed in a metal case capable of supporting a monitor. Inside are a 5.25" drive bay and four low-profile 3.5" bays. Two of the latter are already occupied with a high-density 1.76 Mb floppy drive and 120 Mb IDE Seagate hard drive. A vertically mounted backplane provides four Zorro III 32 bit slots, which are in line with three IBM AT slots and an enhanced video slot.
   All these slots are fully backwards compatible with those found in the A2000 and A3000, making it easy to move cards across from an older system. In my case, I had an A2386 Bridgeboard and PC VGA card from my A3000, and I had also purchased an A2091 SCSI controller and A2320 Display Enhancer (for reasons that will become apparent). The other device I had was a 520 Mb 3.5" Fujitsu SCSI drive, and for the time being, I elected to mount this in the 5.25" bay.
   The only glitch that arose with all this hardware was that the A2091 needed a ROM upgrade, since it didn't understand 32 bit memory and would hang the system while booting. Once I had obtained the necessary chips, the system worked fine.
   So much for my personal setup. What does the A4000 offer over, say, an A3000? The differences can be summed up as follows:

  • 25 MHz 68040 CPU instead of 68030
  • 4 megs of fast RAM, 2 megs of CHIP ram
  • AGA Advanced Graphics Architecture (previously AA) chipset
  • Kickstart 3.0 and Workbench 3.0 as standard
  • 1.76 Mb floppy drive instead of 880K drive
  • IDE hard disk interface instead of SCSI
  • Three IBM AT slots instead of two
  • CPU on a removable daughter card for easy upgrades
  • Memory can be upgraded to 18 Mb using SIMM modules instead of ZIPs
  • 5.25" bay allows CD-ROM or tape drive to be installed
  • Keyboard lock on the front of the case
  • Keyboard uses a slimline connector
  • New, contoured mouse to fit the hand more comfortably
  • Mouse ports on the left side of the case
  • No 15 pin VGA video connector (though a 23 pin to 15 pin converter plug is included)
  • No display enhancer (AGA makes it mostly redundant)

Amazing AGA
By now, much has been written about the AGA chipset, but it's worth mentioning the main features once more. It supports resolutions up to 1280 x 512 at 50 Hz interlaced, including 640 x 480 at 72 Hz and 800 x 600 at 72 Hz interlace (which flickers much less than the standard Amiga interlace). All resolutions now support 256 colours from a palette of 16 million, and all modes now support the new extended HAM8 mode which allows over 256,000 simultaneous colours from 16 million.
   HAM8 is nothing short of stunning, especially at the higher resolutions, and for most people will be indistinguishable from true 24 bit graphics. Since HAM8 only uses the the same bandwidth as a 256 colour screen, it will be very useful for animation.
   Other AGA features include enhanced sprites, which can now be up to 64 pixels wide and be displayed in lowres, highres or super-highres resolution, regardless of the screen mode and a new scan-doubling feature to make it easy to display lowres screens on a VGA monitor (similar to the A2320 Display Enhancer). And finally, all AGA modes take up only 1/4 of the video bandwidth of the equivalent ECS modes, which means that previously CPU-hungry modes like 640 x 512 in 16 colours now zip along.
   So, if this last point is true and the display enhancer is now redundant, why then did I feel it necessary to spend 100 on an A2320? Well, my A3000 monitor was a very nice Hitachi SuperScan multisync which unfortunately can't sync down to 15 kHz, the scanrate used by most Amigas. On the A3000, this wasn't a problem since the built-in display enhancer ensured that the output was always 31 kHz, regardless of screen mode.
   While Kickstart 3.0 on the A4000 can do the same thing, it only works for programs that use the operating system; games and demos that take over the machine will still operate at 15 kHz mode. In addition, Guru Meditation errors and the new Kickstart 3.0 Boot Menu are displayed at 15 kHz.
   On a Commodore 1960 or similar multisync, none of this would be a problem, since they can quite happily display 15 kHz. However, since I like to play the occasional game, I decided the display enhancer would be a good investment. The only disadvantage of the display enhancer is that it can only output 4096 colours instead of 16 million, but it is quite happy to do this at 640 x 480 non-interlace, and the results are really very impressive. And of course, the original output is also there if I need it.
   The other card I purchased was the A2091 SCSI disk controller, which I needed because the A4000 has no SCSI controller as standard (a major oversight in the view of most people; IDE is cheaper, but significantly less flexible). Commodore have said that they will have a Zorro III-based SCSI II controller available some time around January which I intend to upgrade to immediately; I view the A2091 as merely an interim step.

System Software
Apart from AGA, the most noticeable difference with the A4000 is Kickstart 3.0. This fully supports all the features of AGA, and large parts of the low-level graphics.library have been rewritten to increase speed and add features. It incorporates all the features of Workbench 2.1 (soon to be released for existing owners), such as localisation support, built-in CrossDos for accessing 720K and 1.44 Mb PC disks, more flexible device handling, and a PostScript printer driver.
   Workbench 3.0 also includes a new multimedia file viewer called MultiView which can handle a variety of file types, including IFF images, sounds, AmigaGuide help files, ASCII text, and so on. The best thing about MultiView is that it is extensible -- it makes use of one of the new features of Kickstart 3.0, the datatypes.library, which allows additional data types to be defined and added by third parties. Any application program can use datatypes.library, and will then automatically gain access to future formats.
   As a simple example of the kind of thing this implies, imagine a paint program that uses the picture type in datatypes.library. Initially, sub-types IFF and GIF might be defined, so the program could automatically read and write images of those types. Later on, you might add JPEG, BMP and TIFF files; with no changes to the code, the paint program would now be able to handle those filetypes as well. The same applies to sound, text, animations, and so on. The possibilities are endless.

Palette preferences screen
The new Workbench 3.0 palette preferences screen

Another nice feature of Workbench 3.0 is the new Palette preferences editor. This now features a colour wheel to allow colour selection as well as the more familiar RGB sliders. In addition, the colour of each screen element (menu bar, menu highlight, window border, etc) can now be chosen individually.
   Also improved is the Workbench pattern editor, which now offers the capability to install a picture of your choice as a backdrop to your Workbench. If Workbench has fewer colours than your picture, it will be automatically dithered to display a good approximation. Even the mouse pointer has been beefed up, and can now appear in high resolution, removing that chunky look that has so identified it in the past.
   Other changes are more subtle. The layers.library that handles overlapping windows has been greatly optimised, removing almost all the delays that used to occur if you had a lot of windows on the screen. All bitmaps are now interleaved where possible, a technique borrowed from the games world which can greatly enhance graphics performance (since the blitter can do in one operation what used to take two or three). All in all, Workbench 3.0 is a very nice upgrade indeed.
   All this is very nice, you say, but what about speed? This is, of course, the jewel in the crown of the A4000; it is awesomely fast. Overall, it rates about three times the speed of my A3000 on most tasks, which makes it about 20 times faster than your average A500 or A2000. For floating point work, the gains are even more impressive: one benchmark (a ray-traced beach ball, from LaMonte Koop's AIBB benchmark suite) runs a stunning 550 times faster than an A500! Leon, who uses his A4000 for ray-tracing with Imagine, reports that some of his pictures are generated over 200 times faster, and the output in HAM8 is a huge improvement over HAM.

Conclusion
So is this finally the perfect Amiga? Well, no. It has a lot of great features, but also some significant ommissions: no DSP and no onboard SCSI. Commodore has said it's aware of both these failings and is actively working to provide solutions in each area within a few months. A better solution for users with non-15 kHz monitors is also required, since those monitors are now becoming very cheap in comparison to other displays. Overall though, this is the Amiga you've always dreamed off.
   The only thing to marr this otherwise perfect picture is that there seems to be a reliability problem. Out of the three that arrived in Ireland, Rocco's had a faulty CHIP RAM SIMM module (he managed to do a swap at the Developers Conference that weekend, which was handy), and mine stopped working completely after about two weeks. I'm currently waiting for it to be collected by Commodore and replaced, but no sign of anything yet. I am typing this review on an Amiga 1500 which, more than anything, is giving me a good impression of how fast the Amiga 4000 really is!

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Last updated 26 November 2000. Comments to ecarroll@iol.ie.