CRT raster reversal board

Apparatus for reversing the raster scan across the screen of a CRT terminal having a horizontal deflection coil and coupled to a source of supply voltage, said apparatus comprising

• means comprising a clock generator for generating a signal indicative of the font appearing on the screen of the CRT terminal,
• means comprising a flip-flop for latching the signal for a period of time to allow bleed-off of the supply voltage across the horizontal deflection coil of the CRT terminal, a
• first counter,
• means comprising a vertical drive signal for enabling said first counter for a period of time beyond the time for bleed-off of the supply voltage,
• means comprising a first relay coupled to said flip-flop to disconnect the supply voltage,
• means comprising a second relay to reverse the leads connected to the horizontal deflection coil, a
• second counter,
• means coupled to said first counter for enabling the second counter to continue for a period of time after actuating the second relay, and
• means for generating a signal at the end of the period of time after actuating the second relay for resetting the latched signal to enable reconnection of the leads to the horizontal deflection coil of the CRT terminal and thereby reverse the direction of raster scan across the screen of the CRT terminal.