COMPUTER  APPLICATIONS Learning   Objective:   Identify   computer applications. Computer  applications  fall  into  a  variety  of  broad categories. Information   retrieval   is   one   such application,  or  in  a  narrower  sense,  indexing  or cataloging. Information is stored under a variety of key  words  or  index  headings.  By  calling  up  one  of these  headings,  a  listing  of  all  or  part  of  the information  will  be  outputted  by  the  computer. Another application is simulation. This involves simulating the operation of a new computer by using an   older   computer   model.   In   this   way,   design deficiencies can be identified without going through the  time-consuming  and  expensive  process  of building the newer unit. Real-time   control   of   a   production   process   is another application. For example, the petroleum and chemical industries put this process to good use. The computer can detect minute changes in the production process  and  initiate  immediate  corrective  action. The  advent  of  personal  (home)  computers  has greatly expanded the computer-use horizon from the routine upkeep of a checkbook balance to the more complex   functions   of   financial   planning,   home security,  and  computer  video  games. The  application  of  the  computer  and  its  functions is  virtually  endless.    For this reason, there are some people  who  believe  that  the  computer  will  soon control  everything  and  everyone.  This  is  not necessarily the case, however, as computers can do only what their creators have intended them to do. The computer enables people to do more than they have  been  able  to  do  in  the  past.  For  example, computations  that  required  years  to  calculate  by human methods can now be accomplished in a matter of moments by modern computers. This has become particularly  evident  in  our  space  program.  The  ability to put a man on the moon and send  Voyager I  and Voyager  II   on  their  journeys  would  have  been impossible without the use of computers. Fears over job  losses  are,  for  the  most  part,  needless.  While some jobs may be eliminated, new ones are created. Thus, a worker may have to learn a new skill. For example,  a  laborer  may  have  to  be  retrained  as  a computer   programmer   or   operator.   Rather   than destroying  jobs,  the  computer where  none  existed  before. creates   opportunities TYPES OF COMPUTERS Learning  Objective: Identify  the  types  of computers and the analytical processes used by each type. In   general,   there   are   two   basic   types   of computers—  analog and digital. ANALOG  COMPUTERS The  term   analog,   as   applied   to   computers, pertains to representation by means of continuously variable physical quantities. For example, an analog computer  can  be  a  device  that  solves  problems  by setting   up   electrical   circuits   that   represent   the physical  equivalents  of  certain  phenomena.  Then, measurements are made as these circuits are varied in accordance  with  changes  in  the  phenomena.  The analog   computer   is   by   no   means   restricted   to electrical   circuits   as   equivalents.   The   physical equivalents may be gear trains, gases, fluids, etc. Analog computers, because of their nature, have some  inherent  limitations.  The  use  of  physical equivalents limits their versatility. They are limited to performing  only  the  tasks  for  which  they  were designed or, in certain instances, closely related tasks. DIGITAL  COMPUTERS A  digital  computer  is  a  device  that  solves problems  by  manipulating  the  numerical  equivalents of phenomena in accordance with mathematical and logical processes. These numerical equivalents may be  expressed  as  binary  numbers,  octal  numbers, decimal   numbers,   etc.   In   an   electronic   digital computer,  the  numerical  equivalents  are  generally expressed as binary numbers 1 or 0. Values of voltage and current are used to represent the 1s and 0s. The versatility of digital computers is based on the  fact  that  they  use  numerical  equivalents  not  only to  represent  the  data  to  be  processed,  but  also  the instructions for processing the data. In other words, digital  computers  are  generally  provided  with  a  wide variety  of  instructions.  They  are  designed  to  respond in certain ways to the numerical equivalent of these instructions. Programming  is  merely  a  matter  of modifying  and/or  arranging  these  instructions  so  that the  computer  will  respond  in  a  predictable  manner  to a given situation. While much more versatile than an analog system, digital systems are still limited as to 8-2