In each second the machine can perform 30 instructions. An instruction is expressed by 6 digits between 0 and 7 which you can select and, in effect, by 3 more digits fixed by the time (within the second) when the machine reads the instruction. For example, in the 9th instruction of the 30 instructions in each second, we can specify a multiplicand. But, if we do not want to multiply right then—a rare event if we are coding wisely—we leave the 9th instruction empty. The machine may operate as a whole, attending to one problem; or the machine may be separated into halves, and each half will attend to its own problem. The IBM Selective-Sequence Electronic Calculator The IBM Selective-Sequence Electronic Calculator was announced publicly on January 27, 1948, after some months of trial running. It is a large and powerful mechanical brain, and it is the intention of International Business Machines to devote it to solving scientific problems. The staff of the Watson Scientific Computing Laboratory in New York will be mainly in charge of the machine. The machine contains about 12,500 electronic tubes and about 21,500 relays. Numbers in the machine are regularly of either 14 or 19 decimal digits. Instructions are expressed as numbers. For storage of information, the machine has a capacity of 8 registers totaling 160 decimal digits of very rapid memory in electronic tubes. Also, it has about 150 registers totaling 3000 decimal digits of less rapid memory in relays. Also, it can consult any one of 66 paper tape feeds; each row on a paper tape can hold up to 78 punched holes or 19 decimal digits, and the machine can consult 25 rows on one tape in one second. These paper tapes together give the machine about 400,000 decimal digits of memory. For arithmetical and logical operations, the machine has an arithmetical unit using electronic tubes. This unit can carry out about 50 multiplications or about 250 additions per second, including the transfers of numbers. In each second the machine can read and perform 50 instructions, and each instruction consists, usually, of getting two numbers out of two relay registers, performing an operation, and putting the result into a third relay register. Eckert-Mauchly’s Binac As this book went to press, another mechanical brain, the Electronic Binary Automatic Computer, or BINAC, was announced on August 22, 1949. This machine was constructed by the Eckert-Mauchly Computer Corporation, Philadelphia, Pa., for Northrop Aircraft, Inc., Hawthorne, Calif.