Patent GB-909781-A (GB)
IPC: G06F9/32
Abstract: 909,781. Typewriters. NATIONAL CASH REGISTER CO. Dec. 13, 1960 [Dec. 15, 1959], No. 42782/60. Class 100 (4). [Also in Group XIX] An accounting-machine is combined with a magnetic store into or from which data or instructions can be recorded or read. Ledger cards bearing magnetically recorded data can be fed into the machine and the data fed into the magnetic store at a selected location. According to a programme specified by an instruction word read from the card various arithmetical operations are performed on the data and the result is recorded magnetically and by printing on the ledger card. Mechanical arrangements. Keyboard. The invention is applied to an Ellis machine of the type described in Specifications 680,992 and 886,123 to which are added a mechanism 14, Fig. 1, for feeding, reading and recording on ledger cards, and apparatus 15 for computing electronically. The keyboard is modified in that motor bars 23, 27, 28, Fig. 2, are covered up so that they are controlled solely by the computer. A " resume-programme " bar " rpb " is actuated by an operator to initiate a computing operation. Decimal points are indicated for keyboard control by lamps P, P1, P2. Lights EK, EC, HA give visual instructions to the operator to " Enter keyboard word," " Enter card word," and " Halt." The apparatus is combined with an electric typewriter of known, type. Accounting machine portion. This is of the same type generally as described in the abovementioned Specifications. Zeros to the left of the first significant figure are eliminated in printing operations by zero-elimination order hook 76, Fig. 34, which co-operates with a tooth on control plate 78. Significant zeros are printed by stud 53 camming hook 76 out of position during the rearward movement of the amount racks. A disengaged order hook 76 disengages all lower order hooks, Fig. 35. Control of the order hooks is effected by automatic selective energization of solenoids OH1, OH2. The machine has 10 totalizers such as #2-#5, the wheels of which can be brought into mesh with auxiliary racks 55, Fig. 3, whereby digital information can be transferred in either direction. Spring contacts 113, 114 engage printed contacts on the upper and lower faces of switchboard 116 as the racks 55 and rack extensions 98 are moved. The upper and lower faces of switchboard 116 are shown in Figs. 5A, 5B, respectively, the several conductors on the two faces corresponding respectively to digital orders and digital positions of the ten amount racks. The differential position of the first order rack is converted into a pulse on a corresponding terminal 120a-120j by an interrogation pulse on terminal D#. Interrogation pulses are applied sequentially to each of the other order terminals D1-D9. The amount racks can be stopped at positions corresponding to information provided by the computer by the timed operation of ten solenoids such as RA9L, Figs. 4 and 6, each causing an associated pin 138 to engage the saw-teeth of an associated rack extension 98. The time of operation is controlled by a timing rack 149 of the same type but without stopping mechanism. This rack, Figs. 4, 7, 8, has slots for the operation of a photo-cell and a suitable time-lag is allowed for the operation of the stop mechanism. A temporary indication of the digital position of each amount rack is also provided by a switch basket of the type described in Specification 886,123 and shown in the top right-hand part of Fig. 3 and also in Fig. 12, not shown. The amounts are set up on electric switches for the subsequent operation of conventional card or paper punching mechanism. Such operation is initiated in predetermined columnar positions by the operation of switches by stops on a formbar at the back of the carriage. Magnetic ledger card handling mechanism. A ledger card 305, Fig. 22, has a vertical strip 306 of magnetic material along one margin, this strip comprising three channels normally comprising line-find information, clock signals, and digital data. When the leading edge of the card is adjacent slot 375, Fig. 17, light from source 373 is reflected on to photo-cell PCC to energize the amplifiers associated with magnetic pick-ups 346-348. Words are sequentially recorded on the magnetic strip with the highest order digit at the top. When the card is read the order is inverted. Non-significant zeros are suppressed but an end of word indication is recorded. In certain operations a selected ledger card is inserted into box 231, Fig. 1. Thereafter when the computer carriage reaches home position the ledger card is automatically fed into the carriage and after being operated on is automatically ejected again. A magnetic read write assembly 346-348 co-operates with the magnetic strip in both movements. Photo-electric sensing means included in the control circuit of the card handling mechanism ensure that the card is properly aligned. Lack of alignment permits one only of two photo-cells PCA1, PCA2, Fig. 22, to be energized. When the card is placed in position it reflects light on to a photo-cell PCB, Fig. 17, whereby latching cams (Figs. 14 and 16, not shown) position compression rollers to rotate platen 241 to feed the card automatically into the accounting machine carriage and over platen 71. Line-posting information read from the magnetic strip determines the position at which the feed is halted, i.e. so that printing shall take place on a specified line. This is effected by braking solenoid CDB (Fig. 14, not shown). Photo-cell PCB also operates in the subsequent ejection of the card by reversing the motor drive when a dark area of " reversal spot " 376 on the card de-energizes PCB. Magnetic core memory. The memory, Figs. 51, 52, has a capacity of 100 10-decimal-digit words, some of the addresses being used to store instructions. Additional addresses A and B are used to store intermediate results of calculations. Each column of cores is threaded through by two Y conductors 878, 881 each row by two X conductors 879, 880 one of each pair being for reading and recording respectively. A Y conductor is selected by the energization of one Y driver and one Y grounder under the control of tens and units counters W1 and W0 of an address selecting register. An X conductor is selected by the energization of one X driver and one X grounder under the control of 4-bit and decimal counters BC, DC according to the bit and denomination concerned. Thus to record 1 in row 1 address ##, the terminals YD#, YG#, XG#, XDa are energized. The combination of two half-select drive currents through the core saturates it in a positive sense. To store 0 in the same core terminals YG#<SP>1</SP> and XG#<SP>1</SP> would be energized in place of YG# and XG# and the drive currents would therefore be opposite in direction to saturate the core in the opposite sense. A sense conductor 871 is threaded through all the cores for read-out. This is effected bit-bybit by energizing the appropriate X and Y conductors with half-read pulses. Whenever a core changes from 1 to 0 a pulse appears on sense conductor 871. Following the reading of each bit the core just read is restored to 1 if it previously held 1. This is illustrated in Fig. 67A. According to whether a pulse appears or not on sense conductor 871 so lead MSA or MSA<SP>1</SP> goes true. In the former case the X- and Y-driver output lines (not shown) are maintained energized and the read-out is followed closely by a part of half-select current impulses through the core in the opposite direction to restore the core to 1. In the latter case the X- and Y-driver output lines are de-energized so that re-recording does not take place. As described in divided Specification 909,783 the sense conductor traverses successive rows in opposite directions and the half-select current in read-write operations is applied in the X direction 30 seconds before that in the Y-direction to prevent " noise " generating spurious impulses in the sense winding. Control of leads MSA, MSA<SP>1</SP> is effected by inverter 4393 which permits sense winding 871 to operate only at the correct time of the cycle. At other times the inverter is conductive to open-circuit 871. As a further check on noise entering the system the output of sense amplifier 4399 is strobed for 3 seconds as each core is read by one-shot flip-flop 6147 feeding a like flip-flop 6149 whereby gate 1163 is enabled for only 3 seconds in each core-reading time. Memory addresses A and B have a common sense winding 891. The output of their common sense amplifier 4400 is strobed in like manner. Address-selection is effected by a group of binary-coded decimal counters, X- and Y- drivers and bit counters of known type. The counters operate in forward direction only but decoding into the decimal system is inverted, giving effective reverse counting if an instruction is given to read a word out of memory in reverse order. A negative number is stored in the computer memory as its complement. The maximum negative number is 1,000,000,000 and therefore the maximum positive number 8,999,999,999. Both data and instruction words can be stored in the computer memory from keyboard entries, by taking totals or sub-totals, by reading from the magnetic strip portion of ledger cards, from punched cards or paper tapes. Instructions. Stops on the form-bar instruct the machine as to operations to be carried out in the various columnar positions, in the manner described in Specifications 680,992 and 886,123. Alternatively the machine is controlled by instructions stored in the computer memory. In either case the instructions are carried out only when a machine cycle is initiated. Details are given of 18 basic instructions, variously concerned with the ledger card and accounting machine, reading paper tape, and airthmetic and control functions within the computer. The instructions have three different formats. In all cases the instruction word com