Signature Analysis on Crt Controller
Original Publication Date: 1983-Aug-01
Included in the Prior Art Database: 2005-Feb-07
Since signature analysis equipment generates a cyclic redundancy check code (CRC) on the data stream once given a start, stop, clock and serial data signal as inputs, it may be used to test video display controllers. In the past, the serial video data coming from a video display controller was checked in one of two ways. The first method involved connecting an actual video monitor to the card and having the operator verify the operation. With the number of characters, character sets and attributes it is impossible to verify the operation of each in a reasonable time. The second method requires large, expensive hardware to do a bit by bit comparison. For non-interlaced controllers the start and stop signals may be generated from the vertical sync pulse.