Patent GB-806506-A (GB)
Title: Improvements in electronic data processing machines
IPC: G06F7/24
Filed: 1955-11-15
Abstract: 806,506. Electric digital-data-storage apparatus; electronic counting-apparatus; arranging digital-data in sequence. INTERNATIONAL BUSINESS MACHINES CORPORATION. Nov. 15, 1955 [Nov. 15, 1954; Dec. 9, 1954], No. 32633/55. Class 106 (1). An electronic data processing machine having a record reading device for each of a pair of continuous record media and adapted to read input records arranged in random order thereon, a data storage device arranged to receive records read by each of said reading devices, a plurality of means for comparing each record transmitted to said storage device with a record previously transmitted thereto, a pair of record reproducing devices, and means controllable by a comparison result produced by said record comparing means for selecting one of said record reproducing devices for the reproduction of one of said records from which said comparison result was derived. The machine described comprises four high-speed tape units T1-T4, Fig. 2, each being of the type described in Specification 733,807 [Group XVI], which is referred to, together with a control unit comprising two C.R.T. stores M1, M2 and three comparators I/O, I/R and O/R for transferring blocks of data from one tape to another tape, in accordance with the results of the comparisons as determined by pre-plugging. The machine is similar to a punched recordcard sorter and collector, except that the data, per se, rather than the cards carrying the data is transferred from place to place. By virtue of the variety of pluggings possible it is much more versatile than conventional record-card machines, for example, whereas a record card machine can sort on only one column at a time, the machine described can arrange 1000 200-decimal-digit numbers into numerical sequence in at most 10 transfers from tape to tape, and the transfers necessary follow each other automatically. The machine can also duplicate tapes and perform operations analagous to gang punching. Each block of data, referred to as a record, can include up to 200 characters, numeric or alphabetic, each character being registered by bits in seven parallel tracks, in accordance with the code shown in Fig. 4, and successive character positions are referred to as " column positions " by analogy with punched record-cards. The blocks of data are spaced apart on the tape and each terminates with an " end of record " character, which when read from the tape causes tape feeding to stop. In this way blocks of varying length can be read from the take one-by-one. Each C.R.T. store includes two cathode-ray tubes and can store one block of data, and both stores use the same scanning control circuits so that when new data is being inserted into either store the corresponding bit is being regenerated in the other store. Read into and out of the stores is via two 7- trigger registers CR1, CR2 respectively, a character read from a tape being staticized in register CR1 and transferred from there bit-by-bit to a C.R.T. store under control of the C.R.T. scanning circuits, which, during read-in are arranged to be triggered through seven basic bit-storing cycles by the entry of a character into the register CR1. A complete cycle of operation of the machine comprises a read in cycle during which a record is read from a tape (usually either tape 1 or 2) and stored in a C.R.T. store, and a write cycle during which a record is read out of one of the C.R.T. stores and written on one of the tapes (usually either tape 3 or 4). The record read out also remains circulating on one of the C.R.T. stores so that at the end of a complete cycle the two stores contain the record that was read in during that cycle and also the record that was read out during that cycle. During a read in cycle the record read in is stored in the store which contains the record that was read-out in the immediate previous read out cycle which record is thus displaced as the input record is stored. As this happens two comparisons are made: (1) the input record is compared with the record it is displacing, namely, the output record of the previous cycle, by an I/O comparator; and (2) the input record is compared with the record that was not read out in the previous cycle, namely the remainder record, by an I/R comparator. (This is possible because the C.R.T. stores employ the same deflection circuits.) When a read in cycle is completed, which is indicated by the sensing of an " end of record " mark from the tape being read, the machine determines by considering the results of the two comparisons made during the read cycle and also the preplugged connections, which of the two records now stored in the C.R.T. stores should be read out and to which tape it should go, and a read-out cycle is then initiated, during which as the selected record is read out it is compared with the record not being read out (the remainder record) by an O/R comparator. The result of this comparison will, of course, be the same as for the previous I/R comparison because the same two records are being compared (but under different names) and its use is said to be for checking purposes. The physical end of the tape is detected photoelectrically by a reflective spot at the end of the tape. Sorting (i.e. arranging in sequence).-A set of numbers on one or two tapes can be arranged in order of magnitude by a series of two-tape passes through the machine, tapes T1 and T2 and tapes T3 and T4 alternating as input and output tape pairs. A typical pass is as follows: First the machine is cleared and then (a) the first number from tape T1 is read in. No output results. In the second cycle (c) the first number from tape T2 is read in, the previous number from tape T1 now forming the remainder. These two numbers are compared (during the read-in) and (d) the smaller is read out to tape 3. The next input number (e) comes from the tape from which the previous output number came. Of the input and remainder numbers (e) as they are both larger than the previous output, the smaller of them is read out (f). The next number from tape T1 is read in (g) and as this is the same as the remainder, and as both are larger than the output, it is read out (h). The next number from tape T1 is read in (i) and then of the input and remainder numbers one is larger than the output; this is called a " single stepdown " and the larger is read out (j). When the next input is read in (k) both the input and remainder are larger than the output; this is called a " double step-down " and the smaller is read out to the other tape (1), i.e. to to tape T4. The next cycle (m) (n) follows the rule that the smaller of the input and remainder is read out providing they are both larger than the output. The next cycle (o) (p) is a " single step-down," one of the input and remainder numbers being larger than the output, and the larger is read out. The next cycle (q) (r) is a " double step-down " and an output tape change result. Cycle (s) (t) is a normal cycle, the lower being read out. At this stage every number has been read from tape T1, the machine can detect this and reads in a character (u) which is blank, but the machine functions as though infinity (u) had been read in. With this exception cycle (u) (v) is a normal cycle and the lower of the input and remainder is read out. Cycle (w) (x) is a " since step-down " but since infinity has been read in, i.e. since tape T1 is now empty, there is no point in writing a blank (shewn as infinity at (x)) on tape T3 and stage (x) is omitted. Further cycles-cycle (y) (z) in the present example-follow which result in the transference of all the remaining numbers on tape T2 on to tape T4. At the end of the pass, tapes T3 and T4 become input tapes and tapes T1 and T2 output tapes, switches S1 S4, S9 and S10, Fig. 2, being changed over. After one further pass the numbers will all be in sequence on tape T3. C.R.T. store.-Each store comprises two tubes each of which stores 100 7-bit characters arranged as shown in Fig. 10a at 100 address positions numbered from 0 in the bottom lefthand corner and consecutively up each column of 20 in turn to 199 in the top right-hand corner. The deflection plates of the tubes are connected in parallel and input signals are directed selectively to either grid, so there are effectively 200 address positions, the second tube being regarded as containing addresses 100-199. The regeneration, read-out or readin of each bit occupies one 8-point bit-cycle marked by 8 ring-connected triggers 603-610, Fig. 153, which count clock pulses from a 1 mc/s oscillator 599. During the first three points of each bit-cycle, the beam deflecting circuits are allowed to stabilize, during the fourth point the C.R.T. beam is unblanked, writing a dot and reading out the bit previously stored therein, the beam is then either reblanked or kept unblanked for the remaining 4 points depending upon whether it is desired to write a dot or a dash respectively, which can be decided either by the bit read-out if regeneration is desired, or by other means if read-in of fresh data is desired. Data in the C.R.T. is thus always read out as new data is read-in. In order that the dot written in bit-cycle point 4 can be converted into a dash merely by keeping the beam unblanked, the beam deflecting circuits are arranged to give a small horizontal deflection towards the end of every bit-cycle. Every time stage O, trigger 603, of the bit-ring goes on, a pulse is applied via a cathode follower 611, Fig. 154, to advance a 9-stage character-ring comprising triggers 613-621 (Figs. 155, 156, not shown), whose function is to provide two control periods when its first two stages are on, and to position the C.R.T. beam in turn on the 7-bits constituting a character, when its remaining stages go on which it does by superimposing horizontal deflections of from - 3 to +3 units on the deflection produced by a two " 1, 2, 2, 4 " decimal denomination character coun