kingson@uxh.cso.uiuc.edu (Kingson Gunawan) (02/20/91)
I am just wonderring if any of you guys out there know about the followings: 1. What's the difference between rasterops 264 and 364 colorboard? 2. I heard for some cases due to the way si and ci main memory used for the displaying iamges on the monitor instead of a dedicated VRAM, they can get slowed down considerably. Does use of a separate color graphic card eliminate the problem?
long@mcntsh.enet.dec.com (Rich Long) (02/21/91)
In article <1991Feb19.220209.13021@ux1.cso.uiuc.edu>, kingson@uxh.cso.uiuc.edu (Kingson Gunawan) writes... >2. I heard for some cases due to the way si and ci main memory used for the >displaying iamges on the monitor instead of a dedicated VRAM, they can get >slowed down considerably. Does use of a separate color graphic card eliminate >the problem? This seems to be a common question, so : The IIci uses main memory for the video image, worst case consumption being 320K. This video memory comes out of Bank A (4 slots) of RAM. When the video must be refreshed, there is contention between the CPU and video circuitry. The CPU ends up twiddling its thumbs, hence there is some slowdown, proportional to the screen depth. Bank B (another 4 slots) of RAM is not subject to this contention. Therefore, there are several ways to minimize the slowdown: 1. Fully populate Bank B. Applications load into this bank first. When 4MB SIMMs become common, and System 7 bows, you will be able to have 16MB of contention-free memory here. 2. Use a video board. 3. Set your screen depth to 1 (for best performance). The IIsi is probably the same way, though I don't know for sure. The video scheme is fully discussed in the reviews of the IIci that come out at introduction time (late 1989). Richard C. Long * long@mcntsh.enet.dec.com * ...!decwrl!mcntsh.enet.dec.com!long * long%mcntsh.dec@decwrl.enet.dec.com