Electronic device

“ Just as there is no such thing as being a little bit dead, there is no such thing as a partly off digital switch. So our digital computer can make use of the more advanced electronic components to become more complex, or smaller, or both. The analog must sacrifice its already marginal accuracy if it uses more electronics. ”

“ On left is an array of 16 analog computers; at right is a large digital data-processing system.
The facility can perform scientific and business tasks simultaneously.
The dictionary also gives us a good clue to the digital computer: “Digital.—Of the fingers or digits.” A digital machine deals in digits, or discrete units, in its calculations. For instance, if we ask it to multiply 2 times 2, it answers that the product is exactly 4. A slide rule, which we have said is an analog device, might yield an answer of 3.98 or 4.02, depending on the quality of its workmanship and our eyesight. ”

“ The most accurate and reliable analog computers are mechanical in nature. We can cut gears and turn shafts and wheels to great accuracy and operate them in controlled temperature and humidity. Paradoxically, this is because mechanical components are nearer to digital presentations than are electrical switches, magnets, and electronic components. ”

“ It can also “learn” to play a mediocre game of chess.
If we investigate the workings of a digital computer, we find much to remind us of the human brain. First is the obvious similarity of on-off, yes-no operation. This implies a power source, usually electrical, and a number of two-position switches. The over-all configuration of the classic computer resembles, in principal if not physical appearance, that of the human brain and its accessories.
As we have learned, the electronic computer has an input section, a control, an arithmetic (or logic) section, a memory, and an output. ”

“ To achieve such a great increase in speed requires faster electronic switches. Transistors have been improved, and more exotic devices such as tunnel diodes, thin-film cryotrons, magnetic thin-films, parametrons, and traveling-wave tubes are now coming into use. ”

“ Electromagnetic conversion efficiency. The delay line may best be considered as forming an electrical network of the kind usually (rather misleadingly) described as ‘four-pole’, i.e. a network which has one input current and one input voltage which together determine an output voltage and current. Such a network is described by three complex numbers at each frequency. In the case where there is little coupling between the output and input, which will apply to our problem, we may take these quantities to be the input and output admittances and the ‘transfer admittance’. ”

“ Aluminum wire, spun basalt insulation, and aluminum base plates are provided from the bulk or parts fabrication system described in appendix 5F. After these parts are properly presented to the electronics assembly robots, these robots must assemble the components into major working electronics systems such as power supplies, camera systems, mini/microcomputers CPUs, computer I/O units, bulk memory devices, solar cell panels, etc. Electronics assembly appears to require a technology considerably beyond the state-of-the-art. ”

“ A radio tube of the audion or three electrode type consists of a bulb, within which a vacuum has been created, enclosing a filament, which is a negative electrode, or cathode; a plate, which is a positive electrode, or anode; and a third electrode, known as a grid, located between the filament and the plate. The grid is connected with an input circuit, over which electrical radio activity, actuated at the sending station, is gathered from the ether and passes to the grid. When the tube is used as an amplifier, the plate is connected in circuit with a telephone receiver or loud speaker. ”

“ Small machines using a few electronic tubes—much like a radio set, for example—and containing spools of magnetic wire or magnetic tape will doubtless be available to us. We shall be able to use them to keep addresses and telephone numbers, to figure out the income tax we should pay, to help us keep accounts and make ends meet, to remember many things we need to know, and perhaps even to give us more information. For there are a great many things that all of us could do much better if we could only apply what the wisest of us knows. ”

“ Substitution and comprehensive manufacture of electronics components are beyond the scope of the present study. Even with this limited review, it is encouraging to note the number of instances in which space equals or is superior to terrestrial factory environments for the manufacture of electronic components. ”

“ One advanced notion is the “growing” of complex electronic circuitry, in which a completed amplifier, or array of amplifiers, is pulled from the crystal furnace much the way material for transistors is now grown. Pooh-poohed at first as ridiculous, the notion has been tried experimentally. Since a computer is basically a multiplicity of simple units, the idea is not far off at that. It is conceivable that crystal structure can be exploited to produce millions of molecules of the proper material properly aligned for the desired electronic action. ”

“ For several years my attention was almost exclusively directed to the production of an instrument for making and breaking a voltaic circuit with extreme rapidity, to take the place of the transmitting tuning-fork used in Helmholtz’ researches. I will not trouble you with the description of all the various forms of apparatus that were devised, but will merely direct your attention to one of the best of them, shown in fig. 2. In the transmitting instrument T, a steel reed a is employed, which is kept in continuous vibration by the action of an electro-magnet e and local battery. ”

“ The apparatus in use forms part of a circuit
including a telephone and current generator. As the contact is varied
the resistance of the circuit and consequently the current intensity
changes and sounds are emitted by the telephone corresponding to such
changes. If the microphone is spoken to, the telephone will emit
corresponding sounds, reproducing the voice.
It has been found in practice that carbon gives the best microphone
contact. One of the simplest and earliest forms is shown in the cut. ”

“ The mechanism of the transmitter is complicated and cannot be described except scientifically. Its use allows one to talk long distances, even to the extent of 2,000 miles. Non-technically speaking, then, the telephone consists of a magnet, insulated wire, and a disc, the vibration upon the disc being transmitted over the wire from the sending to the receiving station, electricity being used for conveying the vibrations or sound. ”

“ A computer user sits much closer to the screen than most TV-watchers do; might this increase the danger? After all, a typical computer, like a TV, uses a cathode ray tube with a high-voltage charge. An electron gun fires these subatomic particles toward the phosphor coating on your screen. ”

“ These analogies in nature are particularly fitting, since the analog computer is at its best in representing a physical system. While we do not generally recognize such homely examples as computers, automatic record-changers, washing machines, electric watt-hour meters, and similar devices are true analogs. ”

“ Another object of the present invention is to provide a transistor circuit employing field-effect semiconductor devices wherein a field-effect semiconductor device of one carrier type is used as the active load for the field-effect semiconductor device of the opposite carrier type. ”

“ Every one who has listened at a telephone has heard a jumble of noises more or less pronounced, which is the effect of the working of other wires in proximity to those of the telephone. If, when a Morse telegraph instrument is in operation on one of a number of wires strung on the same poles, we should insert a telephone in any one of the wires that were strung on the same poles or on another set of poles even across the street, we could hear the working of this Morse wire in the telephone, more or less pronounced, according to the distance the wire is from the Morse circuit. ”

“ To render the telephone powerful enough to make conversation possible over long distances it was found advisable to substitute for the one telephone a special transmitter, and to insert in the circuit a battery giving a much stronger current than could possibly be excited by the magnet in the telephone at the speaker’s end. ”

“ To send a message by wire, over a telegraph system, a battery or dynamo is used. This establishes a current over wires stretched between two points. By means of what is called a 'key' this current is interrupted, or broken, at certain intervals, making the sounding instrument send out clicks. A short click is called a dot, and a long click a dash. By combinations of dots, dashes, and spaces between the dots and dashes, letters are spelled out. ”

“ The process of sending a wireless message consists in so manipulating the key in the primary circuit of the induction coils that a rapid stream of sparks passes between the secondary balls for a shorter or for a longer time. ”

“ The tendency of design is to make all apparatus capable of carrying without overheating any current to which voltage within Page 290 the telephone system may subject it, and to provide the system so designed with specific devices adapted to isolate it from currents originating without. ”

“ Other analog computers were developed for utility companies to control the dispatching of power to various consumers in the most efficient manner. Again the principle was simply to build a model or analog of an actual physical system and use it to predict the outcome of operation of that system. ”

“ And the mystery of the telephone grows no less the more one studies it. You speak against a tiny disc of sheet-iron, and the disc trembles. It has millions and millions of varieties of trembles, as many as there are sounds in the universe. A piece of copper wire, connected with an electric battery, stretches from the disc against which you have spoken to another disc [Pg 232] miles and miles away. The tremble of your disc sends an electric thrill along the wire to that other disc and makes it tremble exactly as yours did. ”

“ A fertile field for the analog computer from the start was that of industrial process control. Chemical plants, petroleum refineries, power generating stations, and some manufacturing processes lend themselves to control by analog computers. ”

“ When you take your receiver off the hook a tiny electric bulb glows opposite the brass-lined hole that is marked with your number on the switchboard of your central, and the telephone girl knows that you are ready to send in a call—the flash of the little light is a signal to her that you want to be connected with some other subscriber. Whereupon, she inserts in your connection a brass plug to which a flexible wire is attached, and then opens a little lever which connects her with your circuit. ”

“ Bell Telephone uses the computer approach in circuit analysis, and Westinghouse in the design of radar circuitry. It is interesting that as we move up the design scale, closer to what the engineer once considered the domain of human creativity, the computer still is of great value. ”

“ High-speed analog storage permits the machine to make sequential calculations, a job once reserved for the digital computer. But even these advances cannot offset the basic limitations the analog computer is heir to.
84Fewer analog machines are being built now, and many in existence do not enjoy the busy schedule of the digital machines. As the mountains of data pile up, created incidentally by computers in the first place, more computers are needed to handle and make sense of them. It is easier to interpret, store, and transmit digital information than analog ”

“ The action of the transmitter is to send from the battery a series of currents through the coils, which transmit them, greatly intensified, to the earth by means of a wire connected with a buried wire-screen. The electric disturbances set up in the earth travel in all directions, and strike a similar screen buried beneath the receiving instrument, where the currents affect the delicate diaphragm of the telephone earpiece. ”

“ More than 1,000 variables are controlled, and 200 analog signals and 100 digital computer-generated signals are used in the process. The steel sheets are shot out of the rolls at some 45 miles an hour, or about 66 feet a second! A human supervisor would have a difficult job just watching the several hundred signals related to thickness, temperature, quality, and so on, much less trying to think what to do if he noticed something out of specifications. ”

“ But it is to be noticed that the experiment, interesting as it is, hardly comes under the head of a telephone, what is reproduced at a distance being not sound but motion.
'Obviously the invention cannot rest where it is; and no one more readily than the practical telegraphist will welcome an instrument at once simple, direct, and reliable. Even in its present form the telephone may be successfully used where its wire is absolutely isolated from all other telegraph wires. ”

“ The illustration shows a machine in which a picture transparency and a sensitive cell is used at the sending cylinder; and a high speed lamp and photographic paper at the receiving cylinder.
106
107 “Talking Machine” Photograms The spring driven machine illustrated is probably the simplest device possible for the experimental study of transmission of pictures and picture messages by radio or by wire. A conducting ink or pencil line on paper and put on one cylinder (or an insulating coating cut through with a stylus) over which the sending point rides for sending ”