3 How Computers Work
In the past decade or so, an amazing and confusing number of computing machines have developed. To those of us unfamiliar with the beast, many of them do not look at all like what we imagined computers to be; others are even more awesome than the wildest science-fiction writer could dream up. On the more complex, lights flash, tape reels spin dizzily, and printers clatter at mile-a-minute speeds. We are aware, or perhaps just take on faith, that the electronic marvel is doing its sums at so many thousand or million per second, cranking out mathematical proofs and processing data at a rate to make mere man seem like the dullest slowpoke. Just how computers do this is pretty much of a mystery unless we are of the breed that works with them. Actually, in spite of all the blurring speed and seeming magic, the basic steps of computer operation are quite simple and generally the same for all types of machines from the modestly priced electromechanical do-it-yourself model to STRETCH, MUSE, and other ten-million-dollar computers.
It might be well before we go farther to learn a few words in the lexicon of the computer, words that are becoming more and more a part of our everyday language. The following glossary is of course neither complete nor technical but it will be helpful in following through the mechanics of computer operation.
COMPUTER DICTIONARY
Access Time—Time required for computer to locate data and transfer it from one computer element to another.
Adder—Device for forming sums in the computer.
Address—Specific location of information in computer memory.
Analog Computer—A physical or electrical simulator which produces an analogy of the mathematical problem to be solved.
Arithmetic Unit—Unit that performs arithmetical and logical operations.
Binary Code—Representation of numbers or other information using only one and zero, to take advantage of open and closed circuits.
Bit—A binary digit, either one or zero; used to make binary numbers.
Block—Group of words handled as a unit, particularly with reference to input and output.
Buffer—Storage device to compensate for difference in input and operation rate.
Control Unit—Portion of the computer that controls arithmetic and logical operations and transfer of information.
Delay Line—Memory device to store and later reinsert information; uses physical, mechanical, or electrical techniques.
Digital Computer—A computer that uses discrete numbers to represent information.
Flip-Flop—A circuit or device which remains in either of two states until the application of a signal.
Gate—A circuit with more than one input, and an output dependent on these inputs. An AND gate’s output is energized only when all inputs are energized. An OR gate’s output is energized when one or more inputs are energized. There are also NOT-AND gates, EXCLUSIVE-OR gates, etc.
Logical Operation—A nonarithmetical operation, i.e., decision-making, data-sorting, searching, etc.
Magnetic Drum—Rotating cylinder storage device for memory unit; stores data in coded form.
Matrix—Circuitry for transformation of digital codes from one type to another; uses wires, diodes, relays, etc.
Memory Unit—That part of the computer that stores information in machine language, using electrical or magnetic techniques.
Microsecond—One millionth of a second.
Millisecond—One thousandth of a second.
Nanosecond—One billionth of a second.
Parallel Operation—Digital computer operation in which all digits are handled simultaneously.
Programming—Steps to be executed by computer to solve problem.
Random Access—A memory system that permits more nearly equal access time to all memory locations than does a nonrandom system. Magnetic core memory is a random type, compared with a tape reel memory.
Real Time—Computer operation simultaneous with input of information; e.g., control of a guided missile or of an assembly line.
Register—Storage device for small amount of information while, or until, it is needed.
Serial Operation—Digital computer operation in which all digits are handled serially.
Storage—Use of drums, tapes, cards, and so on to store data outside the computer proper.