Digital-to-analog converter

Claim 1

APPARATUS FOR CONVERTING N-DIGIT CODE COMMANDS INTO ANALOG FORM COMPRISING FIRST AND SECOND IMPEDANCE NETWORKS, THE FIRST NETWORK INCLUDING IN PARALLEL A FIRST RESISTOR STRING AND A FIRST LOAD BRANCH, THE SECOND IMPEDANCE NETWORK INCLUDING IN PARALLEL A SECOND RESISTOR STRING AND A SECOND LOAD BRANCH, EACH OF SAID STRINGS HAVING N-X NUMBER OF SERIES-CONNECTED RESISTORS HAVING RESISTANCE VALUES PROPORTIONAL TO THE DIGIT ORDERS OF A PARTICULAR ARRAY OF N-X DIGIT ORDERS OF SAID CODE, MEANS FOR PROVIDING NONLINEAR RESPONSE IN SAID LOAD BRANCHES IN RESPONSE TO SAID ARRAY OF N-X DIGITS OF SAID COMMANDS, SAID MEANS COMPRISING N-X NUMBER OF TWO MODE SWITCHES EACH ARRANGED TO SHORT A RESISTOR IN ONE OF SAID STRINGS IN ONE MODE AND TO SHORT THE CORRESPONDING VALUE RESISTOR IN THE OTHER STRING IN THE OTHER MODE, MEANS FOR CONTROLLING SAID SWITCHES BY SAID PARTICULAR ARRAY OF N-X NUMBER OF DIGITS OF SAID COMMANDS, FIRST AND SECOND OUTPUT CIRCUITS, AND MEANS RESPONSIVE TO THE REMAINING DIGITS OF SAID COMMANDS FOR ESTABLISHING CONNECTIONS BETWEEN SAID OUTPUT CIRCUITS AND SAID LOAD BRANCHES.