Office Systems

C

Computers

During the first half of the 20th century, financial and other numerical record-keeping tasks were performed manually or by bookkeeping machines, billing machines, tabulating equipment, and other types of electromechanical accounting devices. In the 1950s, such machines were increasingly replaced by mainframe computers—large, very expensive, high-speed machines that require trained operators as well as a special temperature-regulated facility to prevent overheating. Use of these machines today is limited to large organizations with heavy-volume data-processing requirements. Time-sharing—allowing more than one company to use the same mainframe for a fee—was instituted to divide the cost of the equipment among several users while ensuring that the equipment is utilized to the maximum extent.

Mainframes with remote terminals, each with its own monitor, became available in the mid-1970s and allowed for simultaneous input by many users. With the advent of the minicomputer, however, a far less expensive alternative became available. The transistor and microelectronics made manufacture of these smaller, less-complex machines practicable. Minicomputers, the first of which entered general business use in the early 1960s, are now widespread in commerce and government. Terminals linked to the central processing unit (CPU) are under the direct control of the individual user rather than centralized staff. In recent years, however, it is the microcomputer, or personal computer (PC), that has come to play the principal role in most office workplaces.

Desktop PCs have become increasingly affordable as a result of industry-wide adoption of the architecture of the PC introduced in 1981. Although it has become feasible to provide virtually every office worker with a PC, it is more cost-effective for PC users to share files and common peripherals such as printers, facsimile boards, modems, and scanners. In the late 1980s and early 1990s, many companies began programs of linking or “networking” multiple PCs into a unified system.

The local area network (LAN) was created in response to the need for a standardized system of linking computers together in a company. The most common method used to connect computers to a network is by means of coaxial cables. Newer-generation networks use optical fiber connections. When computers are not in close physical proximity, networks may use microwave radio or infrared radiation to link the computers. Microwave radio requires a dish antenna for transmission and reception; infrared radiation requires a lens for transmission and a mirror and lens for reception. Other methods used for wide-area networking include telephone and communications-satellite linkage.

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The need for computer “connectivity” has established the usefulness of the peripheral device known as the modem. Modems permit two computers to communicate by telephone in order to access databases, transmit files, upload and download facsimile transmissions, and send and receive electronic mail. Early transmission speeds using this equipment were relatively slow—300 baud (see Baud Rate). Some modems now operate at speeds of more than 50,000 baud and have error-checking and data-compression features.

Text materials in typed or printed form can be input directly into a computer by means of a scanner. To read text, optical character recognition (OCR) software must first be used to convert printed documents electronically into computer-readable files. Scanners obviate the need to rekey printed text in order to input it; they can also be used to input graphic material.

D

Dictation Equipment

Dictation units use a microphone and record/playback device to input speech electronically for storage on a magnetic tape or other magnetic media to be used later for transcription by typists. The equipment commonly includes a foot-actuated control that enables typists to stop, reverse, fast forward, or play a recording while their hands remain free to operate a keyboard.

III

Document Reproduction and Storage

Office machines for the full-size reproduction of documents can be divided into two groups: copiers designed to make one or several reproductions, and duplicators designed to make many copies. Companies still store paper documents in file cabinets of various types, but many documents today are stored electronically or on film.

A

Copiers and Printers

Most modern copiers are electrostatic devices in which document images are created by means of electrical charges and powdered ink, or toner, particles. In the electrophotographic process (see Printing Techniques: Electronic Printing Processes), the most common photocopying method, a mirror image of a printed paged is induced electrostatically onto a metal cylinder from which it is transferred to a sheet of plain paper. Copier speeds range from a few pages per minute to more than 1.5 pages per second. Advanced devices are equipped with automatic feeders, collators, and staplers. Some machines can copy both sides of a document automatically, reduce or enlarge the image, and reproduce color documents in color.

Instead of electrostatic technology, some duplicators employ offset lithography, in which a specially prepared master is used to produce multiple copies. Offset printing, using small presses, is the printing process most often used in modern business offices, usually in large organizations that have a central printing department with trained personnel.

Other, once-common copying and duplicating processes retain a very limited role in the contemporary business office, but may still be found in some schools and other institutions. In spirit duplication, a paper master bearing images formed from carbon dye is moistened with an alcohol solution, dissolving some of the dye, which is then deposited on a piece of paper. This process is repeated rapidly to print multiple copies. In mimeography, a stencil-like master is created by typing or otherwise removing an ink-impervious coating from a fibrous tissue. The master is mounted on a cylinder that forces ink through the stencil onto paper. The diazo process, using ammonia-sensitive paper, is still used in engineering and architectural offices to reproduce graphics at scales that can only be accommodated on large sheets of paper.

B

Computer Printers

A considerable volume of office computer output is via the printer. Among the earliest printers used with PCs in business offices were daisy-wheel and thimble printers, so-called because of the shape of their printing elements. Although their type quality was comparable to that of a typewriter, they were slow and could accommodate only text, not graphic materials. As a result, they have been supplanted in most offices by dot-matrix, ink-jet, and laser printers. The dot-matrix printer may have a 9- or 24-pin print head. The pins impact the paper through a ribbon, creating patterns of dots in the shape of letters and numbers in multiple fonts and type sizes. The ink-jet printer, an advance over the dot-matrix, provides both high resolution (the higher the resolution, the better the print quality) and quiet operation. The laser printer represents an even greater advance. Similar in technology to a photocopier, it offers speed, high resolution of 300 dots or more per inch, ability to reproduce complex graphics, and silent operation—all of which make it virtually essential for desktop publishing.

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