GB911051A - A circuit arrangement for checking the validity of binary numbers - Google Patents

Abstract

911,051. Digital electric calculating apparatus. OLYMPIA WERKE A.G. March 3, 1961 [April 11, 1960], No. 7829/61. Class 106 (1). In an arrangement for checking whether a combination of binary digits represents a coded digit in a binary excess code, sections of the digit positions which have combinations of binary digits occurring only in numbers in the code, are checked. As described, for an excess twenty-seven code, in which a decimal digit n is represented as the binary number n+27, the representation for the digits 0-9 are shown in Fig. 2, the section comprising the first four code positions being characterized by the combination 0111 for digits 1-4 and 1000 for digits 5-8. A number to be checked is stored in a six-plate register comprising bi-stable stages FF 1 -FF 6 , the " 0 " and " 1 " outputs from the stages being applied to " and " gates U 1 -U 4 . The gate U 1 produces an output if 011011, representing decimal zero, is stored, the gates U 2 , U 3 producing outputs if the combination 0111 and 1000 respectively are stored in flip-flops FF 1 - FF 4 and the gate U 4 producing an output if 100100, representing decimal nine is stored. The outputs of the gates U 1 -U 4 are connected via an inverter I 1 , to a further " and " gate U 5 supplied with synchronizing pulses at P. The arrangement is such that when a binary digit combination to be tested is stored in the stages FF 1 -FF 6 , the application of a synchronizing pulse at P causes an output at A if and only if the binary digit combination does not represent a decimal digit 0-9 in the excess twenty-seven code.