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INTERCOMPUTER I/O OPERATIONS - 14100_204
TOPIC  1COMPUTER INSTRUCTIONS

Fire Controlman Volume 03-Digital Data Systems
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CHAPTER 8 COMPUTER  INSTRUCTIONS  AND MAN/MACHINE  INTERFACES INTRODUCTION You  have  probably  heard  people  talk  about  the  various  computer  programming languages used to write computer programs. Maybe you have even written some. Programming  languages  include  procedural-type  languages.  Examples  are COBOL  (COmmon  Business  Oriented  Language)  to  solve  business-type  problems, and FORTRAN (FORmula Translation) to solve mathematical-type problems. Other languages are interactive languages that enable a person to communicate with a computer in a conversational mode to develop programs. BASIC (Beginner’s All-purpose Symbolic Instruction Code) is an example of an interactive language. Another language called Ada is the language developed for the Department of Defense for use in embedded applications; for example, where a computer serves as a control system. (Ada is named for Ada Augusta Byron, Countess of Lovelace, for her achievements relating to computers. She was a full collaborator and suggested the use of the binary system rather than the decimal system to Charles Babbage, who is recognized as the father of computers.) These are all considered high-level programming languages in that their instructions are in human readable form, such as ADD A to B; LET X = Y; IF A > Y, THEN PRINT Y; and so on. These types of instructions must be translated into machine code for execution by a computer. This is accomplished through special language translation programs. For high-level languages, a compiler program maybe used. There are two other levels of computer languages: assembly language and machine language. Assembly languages use mnemonics, symbols, to represent operations. For example, “A” might mean add and “STR” might mean store. Like high-level languages, these must be translated before a computer can execute the instructions. To translate assembly language programs, an assembler program is used. By now, you have probably noticed that for an instruction to be executed, it must be in machine code that consists of a series of 0’s and 1’s—the only things a computer can understand. You have probably also realized that to write instructions in 0’s and 1’s would be tedious, difficult, and time consuming. Therefore, the assembly languages and the high-level languages provide easier means for people to use to interface with computers to specify the steps a computer is to perform. As a technician who is looking primarily at the internal functions of a computer, you need   to   understand   machine   code   and   how   it   works.   Some   of   the operator/maintenance  panels  display  information  in  binary,  as  you  have  already learned. It will be up to you to interpret codes as meaningful information. Other displays present information in commonly used words, terms, and numbers. In these  cases  a  computer,  through  program  instructions,  translatet/interprets  the binary codes into meaningful information. This information is then presented to you. 8-1






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