sands@apple.com (Michael Sands) (03/28/90)
There is an upgrade from the Macintosh Display Card 4(dot)8 to the 8*24. You buy additional memory and plug it into the SIMM sockets. This upgrade is one meg of VRAM. The Macintosh Display Card 8*24 GC (what a mouthfull!) cannot be created out of the plain 8*24 card. The graphics accelerator uses the AMD 29000 general risc processor to gain acceleration over the other frame buffer cards. All these cards drive all monitors currently available from Apple. They plug and play. They are also capable of NTSC output and Apple's convolution, a method of reducing flicker on interleaved displays. The NTSC is color if you use a video conversion box. The 8*24 GC is capable of master block transfers on the NuBus and it uses this function to accelerate the QuickDraw rendering on other framebuffer cards plugged into the NuBus slots. These other cards need to be capable of slave block transfers. The Mac IIci's framebuffer is not on NuBus but it is accelerated. It should be noted that the acceleration in all these cases is not consistent and varies according to the bit depth, QuickDraw calls being used, CPU, and other cards in the NuBus slots. Some of the applications do not use the off screen bit map support offered originally with the introduction of 32-bit QuickDraw. These features were placed there deliberately in anticipation of the graphics accelerator. Some applications will therefore not run as fast as they could. It is important to note that everything is accelerated. An often forgotten result of using the graphics accelerator is the additional time the Mac now has to do processing, once relieved of having to do the graphics. Not only do the graphics go faster, but the applications fly as well! Isn't it wonderful what parallel processing can do? Michael Sands system extension group (408) 974-6108 novice driver, just my thoughts
sands@apple.com (Michael Sands) (03/29/90)
I apologize for giving short answers. Sometimes you get too close to a problem. The NTSC ability of these cards is a bit strange. The timings are all there and if you hack the cable you can get black and white images. The sync is off the green. In order to obtain the color display, which is there, you must go through a video conversion box. This box takes the correct timings and adds the color burst. There are external boxes and are available from third party developers. Sorry if there was any confusion. Michael Sands system extension group (408) 974-6108 novice driver, just my thoughts