Digital comparator

Claim 1

IN A DIGITAL SERVO SYSTEM RESPONSIVE TO DIGITAL COMMAND SIGNALS AND INCLUDING OUTPUT MONITORING MEANS PRODUCING DIGITAL FEEDBACK SIGNALS AN ERROR INDICATOR COMPRISING: A PLURALITY OF STAGES EACH HAVING A FIRST INPUT TERMINAL CONNECTED TO THE INPUTS OF A FIRST "AND" CIRCUIT AND A SECOND "AND" CIRCUIT, A SECOND INPUT TERMINAL CONNECTED TO THE INPUT OF SAID SECOND "AND" CIRCUIT AND A THIRD "AND" CIRCUIT, A THIRD INPUT TERMINAL CONNECTED TO THE INPUTS OF SAID FIRST AND THIRD "AND" CIRCUITS, MEANS CONNECTING THE OUTPUTS OF SAID "AND" CIRCUITS TO THE INPUTS OF AN "OR" CIRCUIT, AND AN OUTPUT TERMINAL CONNECTED TO THE OUTPUT OF SAID "OR" CIRCUIT, THE OUTPUT TERMINALS OF SUCCESSIVE ONES OF SAID STAGES BEING CONNECTED TO THE SECOND INPUT TERMINALS OF THE STAGES BEING CONNECTED TO THE SECOND TERMINALS OF SAID STAGES BEING ENERGIZED BY SAID DIGITAL COMMAND SIGNALS, THE THIRD INPUT TERMINALS OF SAID STAGES BEING ENERGIZED BY SAID DIGITAL FEEDBACK SIGNALS, AND THE OUTPUT TERMINAL OF THE STAGE ENERGIZED BY THE MOST SIGNIFICENT DIGIT SIGNAL OF SAID COMMAND SIGNALS AND SAID FEEDBACK SIGNALS PRODUCING AN ANALOG ERROR SIGNAL HAVING A FIRST VALUE WHEN SAID COMMAND SIGNAL EQUALS SAID FEEDBACK SIGNAL, A SECOND VALUE WHEN SAID COMMAND SIGNAL EXCEEDS SAID FEEDBACK SIGNAL, AND A THIRD VALUE WHEN SAID FEEDBACK SIGNAL EXCEEDS SAID COMMAND SIGNAL.