ksg (03/10/83)
Having used (and abused) the matrox RGB Graph board, I have a few comments for anyone planning to use this board. First, it is not a bad board, although it does have certain quirks that can sometimes make a programmers life miserable. First of all, the X and Y coordinates are write-only. This would not be so terrible, except that the board also has a vector-displacement mode, which makes keeping track of one's position on the screen something of a chore. This is also true of the zoom registers. One of two major hardware bugs which we found in the board is that the memory refresh does strange things when the display is zoomed, resulting in the loss of most of the other (non-displayed) data on the screen. Whether this is the result of faulty design, a PC board error or a bad chip on our board, I couldn't say. The other hardware problem most likely involves the matrox interface with the Mutibus - at random intervals, the graphics board will "drop" some data on the screen - pixels which should have been drawn aren't, while pixels which hould have been erased remain on the screen. This is particularly aggravating if you are trying to do a real time, moving display, since the un-erased pixels ruin the effect completely. Again, whether this is due to poor design or just a freak effect on our board is unclear. However, I would suggest leaving the matrox board in zoomed display mode (4x4) for over 2 minutes, then restoring the display to 1x1 to see if any data has been lost. As for the dropped bits, I have no idea what causes that effect, so let the buyer beware... Ken Goekjian philabs!ksg