The card is an external device that attaches to the RGB port of any Amiga, and has an RGB output to connect the monitor (any 15kHz capable monitor, like the 1084 or M1438).
Two examples of software using the Graffiti card are Nemac IV and Trapped. There are demos of both on Aminet. The card includes a 256 color IFF viewer for all models of Amiga, and very fast Graffiti drivers are now supplied with the Emplant Macintosh emulator.
In the near future there will also be an AVI/FLI player.
Independent review by Toni Pomar
What is Chunky Pixel format?
Before we can review the card we must understand why it is necessary, because its only purpose is to add 256 color ´chunky´ modes to the Amiga.
Until now the graphics in Amiga has been stored and showed in bitplane format. That means that every pixel is broken into all of its bits, and each bit is placed in a different ´layer´ (a bitplane). This way, bitplane 0 contains all the first bits of all the pixels, bitplane 1 contains all the second bits of all the pixels, and so on... This is called the bitplane format.
On the other side there is the chunky format, used by other platforms like PC, Macintosh and X-Windows, in its 256 color modes. In this format each pixel in the screen is one byte in the graphics memory (it is called ´chunky´ because all the bits of a pixel are stored in one chunk, a byte).
Each format has its advantages and its problems, depending on what you want to do, so the best solution is to have both formats available, and to use the more suitable format for each case. With the Graffiti you have that.
Why does the Amiga need ´Chunky´Modes?
Until some time ago, the bitplaned graphics has been perfect for all purposes. Now, when the CPU power has increased to a certain level, there is a new kind of game that use this power. These are the ´texture-mapped´ games, that use 3D objects with graphic textures in its surface (like DOOM and some flight simulators). Because of the kind of calculations used for these games, to process and show the graphics in chunky format is a lot more suitable than in bitplane format.
There has been several solutions tried in the Amiga software to overcome the bitplane limitation, by converting the whole screen from chunky to bitplane format in realtime (like in the excellent Breathless game), or by using the copper to create real chunky 4096 color modes (Gloom and Alien Breed 3D). The first solution requires a good deal of CPU power to make the conversion, and the second solution is very limited about the resolution available. The Graffiti is the hardware solution to this, because with it the screen in CHIP memory is stored in true 8 bit chunky format. There are 256 colors from a palette of 262,144, the resolution is much higher than with copper screens (up to 768 pixels with AGA and 384 pixels with OCS/ECS) and doesn´t need the CPU power required by the realtime conversion software.
What does the Graffiti do? The main characteristics of the Graffiti are :
The Software
The Hardware
The card is a small box, with an RGB input on one side and an RGB output on the other side, so it is connected between the computer and the monitor.
With the card there is a user manual and an installation disk. On connecting the card for the first time you can see that when the Graffiti is not active (it is activated by software) the through port simply passes the original Amiga display to the monitor, without restrictions of frequencies or colours. Then you have to configure the 2 dip-switches of the card (starting the ´Config´ program and moving the dip-switches until the image is OK) to prepare it for your model of computer (necessary only for OCS/ECS machines).
If you have any problem with the card then you probably have some kind of cable between the computer and the card. This cable must be as short as possible, and must contain all the signals of the RGB port (well, to avoid the typical ´vertical bars´ problem you can exclude the C1 signal, pin 15 of the RGB port, as the Graffiti doesn´t need it).
Then you can test the 256 colors available with the IFF viewer (for this purpose there is a 256 color picture on the disk, called Katze.256). To see 256 colours with the A500 is very nice :-)
As a last test, we test the only two games that support Graffiti right now. These are Nemac IV and Trapped. Both games are in demo version in Aminet (game/demo/TrappedPreview.lha and game/demo/nemac4e1.lha).
The Graffiti modes of both games, compared with native chipset modes, are faster and with higher resolution (usually 1x1 pixels). In the 68030/42MHz I can play with Nemac IV at 256x190 pixels, 1x1, with all textures activated, and at full screen with ceiling and floor deactivated. In trapped, the game is always full screen in Graffiti mode.
Problems?
The only hardware problem is the lack of the 12V power at the RGB output of the card, so modulators like the old C= A520 will not work unless you can feed it from another source or you modify the card (by adding a cable from 12V to 12V output).
This is no problem for owners of monitors or SCART TVs with RGB.
Another problem is about space. In the A1200 the CVBS connector is very near to the RGB output, so with the Graffiti plugged in is really difficult to connect something to the CVBS output of the computer.
About the software, the programs usually have problems to show the screen when the user has modified the overscan settings of the PAL/NTSC/Euro36 monitors, and the software doesn´t know how to read the overscan settings to shift the screen to the right place so the card can fetch the video data correctly.
In order to work properly the left border of the overscan settings must be at an 8 pixel boundary (that means, 0, 8, 16, 24, etc...). In the case of the Euro36 monitor, you must add 4 pixels to the left border (so the correct values are 4, 12, 20, 28, etc...).
Conclusion
This card fills, at a reasonable price, the gap left by the Amiga custom chips designers, that never included any chunky mode in them.
With this device we can now port games like DOOM or Dark Forces to the Amiga just like they had been ported to the Macintosh. Moreover, it eases the emulation of other platforms (like Macintosh, PC and X-Windows) and some image manipulations (what about a Photogenics driver?).
Well, the only thing I can add is that this gadget is now permanently connected to my computer :-)
Price : £ 89.95 UKP
