GB878085A - Improvements in or relating to magnetic recording devices - Google Patents

Abstract

878,085. Checking arrangements for magnetic drum data stores. BRITISH TELECOMMUNICATIONS RESEARCH Ltd. April 23, 1959 [May 12, 1958], No. 15202/58. Class 106 (1). Information read at R1 from track 1 of a magnetic drum store is written back into its original position at W1 after processing at M1 (as described in Specification 826,230 in connection with telephone charge registers) a delay track 2 with write and read heads W2, R2 providing the appropriate delay and an erase head W3 preventing delay track information being read more than once in the event of failure of write head W2. Switches TS enable the delay track to be associated with any of a number of main tracks, and a unit Z detecting unsatisfactory read-out (as by failure of write head W2) then inhibits writing at W1. Fig. 3 (not shown) illustrates a modification in which information from R1 in addition to being entered at W2 is processed by a unit identical with M1 and the result entered on a sector of track 2 to be read off and compared with the processed data reentered by head W1, any discrepancy giving an alarm and preventing further writing at W1. Fig. 4 (not shown) illustrates the simultaneous use of a number of sectors of delay track 2, one for each of a number of main tracks. Specification 868,317 also is referred to.