Patent GB-817516-A (GB)
Title: Storage system for messages of various lengths
IPC: G06F3/08
Filed: 1955-11-22
Abstract: 817,516. Electric digital-data-storage apparatus. INTERNATIONAL BUSINESS MACHINES CORPORATION. Nov. 22, 1955 [Nov. 24, 1954], No. 33391/55. Class 106 (1). In apparatus for storing variable length data words, in succession on a plurality of tracks on a magnetic drum, control means are provided for comparing the length of each word, before it is stored, with the available space on the track on the drum in which the preceding word was stored and then as a result of the comparison, for storing the word either in that track-if there is room for all of it-or in the next track. In this way the tracks on the drum are sequentially filled as far as is possible without splitting a word. As described, each word is read from a record card and staticized in some manner not described, a marker digit is affixed to the end of the word while in the staticizer, and the word is read out of the staticizer in serial form to the drum store under the control of a timing pulse from the control means. The transfer of each word from the staticizer to the drum store takes place in four steps : (1) Initially, while the word read from the card is being staticized, a contact 51, Fig. 4, is closed maintaining a four-stage timer chain in its zero or reset condition, and a single pulse is recorded somewhere on a " roving sync. A " track. During each revolution of the drum, this pulse on the sync. A track passes via an amplifier 38 to a timer advance input and also via a transfer switch 37 and a " scan start " lead 28 to initiate the read out of the word from the staticizer. While contact 51 is closed, however, i.e. while the word is being staticized, this pulse has no effect. Once the word has been staticized contact 51 opens, and the next time the pulse is read from sync. A track it advances the timer one step and initiates the read out from the staticizer of the word therein -the word passing via a lead 26 to an intermediate storage track 32. Then the position of the first digit of the word when recorded on the intermediate track corresponds to the position of the timing pulse on the sync. A track. (2) During the next rotation of the drum the pulse on the sync. A track advances the timer a further step to its stage numbered 1, the word is read from the intermediate store to a comparer, its marker digit also passing to the sync. B track, and the contents of track 1 of the main store are also passed to the comparer, which is such that it only provides an output if any digits reach it from track 1 before the end of the word marker digit reaches it. (3) During the next revolution of the drum the timer is advanced a further step by the pulse from the sync. A track and, assuming no digits reached the comparer from track 1 before the end of word marker digit did, the word is transferred from the intermediate store to track 1. Had a digit reached the comparer from track 1 before the end of word marker digit, then the comparer would condition a transfer gate 43 to transfer the word not to track 1 but to track 2 which is empty. (4) During the next revolution of the drum the timer is advanced to its final stage when it causes an erase signal to be applied to the sync. A track and the intermediate storage track. The device is ready to receive the next word. As the next word is being read from a card and staticized, the timer is reset and an alternate card control input 47 changes over transfer switches 37, 40 and 46. The result being that the pulse recorded on the sync. B which is in a position corresponding to the position of the end of the last word recorded in the main store track is effective to control the recording. Specification 667,784, [Group XXVI], is referred to.