Selecting adder

Claim 1

IN A LOGICAL ADDER THE COMBINATION OF INPUT MEANS FOR SUPPLYING VOLTAGE SIGNALS REPRESENTATIVE OF AUGEND AND ADDEND DIGITS, OUTPUT MEANS THE VOLTAGE STATES OF WHICH REPRESENT SUM DIGITS, SAID INPUT AND OUTPUT MEANS BEING DIVIDED INTO A PLURALITY OF FIRST LEVEL GROUPS, EACH OF SAID FIRST LEVEL GROUPS IN TURN BEING DIVIDED INTO A PLURALITY OF SECOND LEVEL GROUPS, EACH OF THE SECOND LEVEL GROUPS THEREBY HAVING INPUT MEANS FOR SUPPLYING VOLTAGE SIGNALS REPRESENTATIVE OF A SUBAUGEND AND A CORRESPONDING SUBADDEND, AND OUTPUT MEANS THE VOLTAGE STATE OF WHICH REPRESENTS TRUE SUBSUM DIGITS; FIRST MEANS ASSOCIATED WITH EACH OF SAID SECOND LEVEL GROUPS RESPONSIVE TO SAID SUBAUGEND AND SUBADDEND INPUT MEANS FOR PRODUCING VOLTAGE SIGNALS REPRESENTATIVE OF A FIRST SUBSUM AND A FIRST GROUP CARRY OUTPUT, SAID FIRST GROUP CARRY OUTPUT BEING GENERATED SIMULTANEOUSLY FOR ALL GROUPS; SECOND MEANS ASSOCIATED WITH EACH OF SAID SECOND LEVEL GROUPS RESPONSIVE TO SAID SUBAUGEND AND SUBADDEND INPUT MEANS FOR PRODUCING SIMULTANEOUSLY WITH SAID FIRST MEANS VOLTAGE SIGNALS REPRESENTATIVE OF A SECOND SUBSUM HIGHER BY ONE THAN SAID FIRST SUBSUM AND FOR PRODUCING VOLTAGE SIGNALS REPRESENTATIVE OF A SECOND GROUP CARRY OUTPUT, SAID SECOND GROUP CARRY OUTPUT BEING GENERATED SIMULTANEOUSLY FOR ALL GROUPS; MEANS ASSOCIATED WITH EACH OF SAID FIRST LEVEL GROUPS RESPONSIVE TO THE GROUP CARRY OUTPUT SIGNALS FROM SECOND LEVEL GROUPS HAVING DIGITAL POSITIONS OF LOWER DIGITAL ORDER FOR PRODUCING A RESPECTIVE CARRY INPUT SIGNAL INTO EACH FIRST LEVEL DIGITAL GROUP; AND MEANS WITHIN EACH OF SAID FIRST LEVEL GROUPS RESPECTIVELY RESPONSIVE TO SAID CARRY INPUT SIGNALS AND TO THE GROUP CARRY OUTPUTS FROM SECOND LEVEL GROUPS WITHIN THE RESPECTIVE FIRST LEVEL GROUP WHICH HAVE DIGITAL POSITIONS OF LOWER DIGITAL ORDER TO SELECT THE SUBSUM FOR EACH SECOND LEVEL GROUP CORRESPONDING TO THE TRUE SUBSUM.