Patent GB-1010523-A (GB)
Title: Improvements in electric digital data storage devices
IPC: G11C15/06
Filed: 1963-05-16
Abstract: 1,010,523. Manipulating and storing digital data. INTERNATIONAL BUSINESS MACHINES CORPORATION. May 16, 1963 [May 28, 1962], No. 19416/63. Headings G4C and G4M. A cryotron store is capable of performing the following functions: (a) Read-out of its contents sequentially in an order determined by the relative numerical values of fields within the stored words; (b) " Push-down " storage; (c) The function (a) combined with (b) so that the words are ordered in the store; (d) An associative memory; (e) Parallel write-in, the store being filled in one write operation; and (f) Selection of words according to a preassigned priority. The functions (a) and (f) are performed as is described in Specification 1,010,522. As in that application, associated with each storage register is an ordering circuit, e.g. the input 276-3 (Fig. 4e), which is continually energized and if the register contains the lowest word of the sequence energizes a select line 80C (Fig. 4f) otherwise a reject line 142. Three flip-flops are provided with each word register on a status flip-flop, e.g. 277-3 indicating whether a register is full or empty, a readout flip-flop, e.g. 281-3, set when the word in the register has been read-out during a current operation-this need not mean that the register is empty-and a flip-flop, e.g. 296-3 set while the register is being operated on. Between the word registers are intermediate registers comprising the same number of storage flip-flops as in a word register and flip-flops such as 327-3 and 354-3 which receive the settings of the status and read-out flip-flops. Push-down store.-The word is entered into the register comprising flip-flops 66A, 66B and' read-out flip-flop 347 (Fig. 4b), the switch 356 is set as indicated in Fig. 4a and generator 352 is started. The S pulse is steered to line 382 to determine the status of the registers. If the top register is empty gate 384-1 is resistive and the S pulse is suppressed. If, however, the register is full gate 386-1 is resistive and the S pulse transfers the setting of flip-flop 277-1 to the intermediate register status flip-flop 327-2 by sending gate 388-2 resistive, and transfers the settings of flip-flops 281-1, 60A and 60B to intermediate register flip-flops 354-2, 68A and 68B. The status flip-flop 277-2 of the next word store is then sensed and if the store is empty the S pulse is suppressed, otherwise the contents of the store are transferred to the next lower intermediate store, whereafter the next lower word store is examined and if necessary transferred down. The T pulse prepares the data storage flip-flops 60A etc. for reception of the contents of the intermediate stores. Each flip-flop is associated with a loop in which, when the flipflop is storing a one, a clockwise persistent current circulates. In flip-flop 60A this loop is conductor 414A (Fig. 4b) comprising control windings of cryotron gates 452A, 454A and the gate 420A. When persistent current is present it opposes a bias on gate 454A to leave the gate superconductive whereas it maintains gate 452A resistive. The T pulse is applied to the control winding of gate 420A, stops the flow of persistent current and thus sends gate 454A resistive and gate 452A conductive. Before the T pulse ends a U pulse issues. This sets the status flip-flop 277-1 to full, transfers the contents of flip-flop 347 to flip-flop 281-1 and the contents of 60A, 60B to 66A, 66B. If 60A is storing zero, gate 442A is resistive and the U pulse by-passes flip-flop 66A. If 60A is storing one, gate 444A is resistive and the U pulse is steered through the windings of gates 454A, 452A as the T pulse is maintaining gate 420A resistive. On the removal of the T pulse a circulating current will be set up in the loop 414A and, since gate 452A is resistive, current is steered into the left-hand limb of the flip-flop loop. Lower words receive, by the action of the U pulse, the contents of the intermediate stores and the push-down operation is completed. Ordering words in store.-The sequential readout operation described in the above-mentioned application is performed but the word read-out is entered into the entry register, after which a push-down read-in operation is performed. At the end of the sequence the highest ordered word occupies the top storage register and the lowest, the bottom register. Associate memory.-The tag is set by marking those lines 538A, 538B etc. where there is one in corresponding orders of the tag. The effect on the data storage flip-flops is the same as the T pulse: to set those flip-flops which are storing one to zero. Thus a word which corresponds to the tag will have a tag field of zeroes. The sequence selecting circuitry will pick out such a word as having the lowest numeric value of the words in store (see the application referred to above) and the word will be read out when the read-out pulse generator 232 is operated. The tag field will, however, have in it all zeroes. Parallel write-in.-The words to be entered are set in the intermediate registers using the cryotrons such as 348A, 350A (Fig. 45). Switch 356 is set to parallel write and the write pulse generator started. The S pulse will set all the status flip-flops to full and reset all the intermediate register read-out flip-flops 347, 354-2 etc. The remainder of the cycle is as in a push down entry.