What is a scan converter?
A scan converter is a device that you connect between your computer and a regular television or monitor to allow them to display computer signals. The idea sounds good, but in reality when you convert a computer signal this way it becomes very difficult, or impossible, to read text, although pictures will look satisfactory. The reason for this becomes obvious if you refer to the above articles on VGA and horizontal and vertical resolution. Even the best televisions or non-data monitors are designed to NTSC standards which gives you a maximum resolution of 400 x 525. VGA computer signals are 640 x 480 and the higher resolution SVGA or XGA are fast becoming the standard making the problem even worse. No matter what you do, you cant clearly display 640, or more, lines of information on a monitor only capable of 400. So, unless you are planning to display nothing but pictures, or very large text, a scan converter probably wont do what you hope it will.
. In either case, this is a non-trivial project. IMHO, this is a poor use of an expensive monitor. A $200 TV will likely look better. An even simpler approach is possible as well which only requires a one or two line buffers instead of a full frame store. Each input line is read in and reformatted to the appropriate VGA line (even or odd) depending on which field is being displayed. The other lines are blanked (i.e., display even lines and blank the odd lines during the even field display). This would only require enough buffer memory for one or two scan lines (depending on whether the implementation uses a double buffer or more sophisticated write and read timing) which would be a significant cost and complexity savings compared to a full frame store. The disadvantage is that since half the lines are by necessity left blank, the maximum possible brightness of the display will be reduced. It is not possible to use the blank lines as the interleaving of the even and odd fields will be i
