[net.periphs] Matrox RGB Graph 512x512

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