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COMPUTING DEVICE (PRE – COMPUTER AGE TO 19TH CENTURY)

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(i)                   ABACUS: This is the first calculating device invented by Chinese. It is made up of a frame divided into two parts by a horizontal bar an vertical threads. It is also known Soroban in Japan and Suan Pan in China. It is used for adding and subtracting numbers. (ii)                 JOHN NAPIER BONE: In 1917, Scotsman named John Napier invented logarithm which are a technology that allows multiplication. It consists of a set of eleven rods, with four sides each used as a multiplication tool. These rods were made with bones. (iii)               SLIDE RULE: Napier’s invention led directly to slide rule. It was first built in England in 1632. It uses two logarithm scales to allow rapid multiplication and    division of numbers. ...
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ACCESS A SEQUENTIAL FILE

ACCESS A SEQUENTIAL FILE Data stored in a sequential file can read in order and assigned to variables with the following steps: 1.       Choose a number from 1 through 255 to be the reference number of the file. This number is not necessary to be the same number that was used when the file was recorded. 2.       Execute the statement OPEN filename FOR INPUT AS #n Where n is the reference number. This procedure is referred to as opening a file for input. It establishes a communication line between the computer and the disk drive for reading data from the diskette. 3.       Read data from the file with the INPUT* statement. INPUT* statement assigns data from file to variable. INPUT #n. var1, var2, …… 4.       After the desired items have been found or all the data has been read from the file, close the file with the statement CLOSE #n. 5.       Ba...
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LOGIC CIRCUIT

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LOGIC GATES A logic gate is an elementary building block of a digital circuit. It processes one or more input signal in a logical fashion. Depending on the input value or voltage, the logic gate will either output a value of ‘1’ for ON or a value of ‘0’ for OFF. BINARY CODE Logic gates are digital circuits and they utilize a binary numbering system known as binary code. Binary code is the same language used by computer which uses only 1 or 0 as numbers. INPUTS AND OUTPUTS Gates have two or more inputs, except a NOT gate which has only one input. All gates have only one output. Usually the letters A, B, C and so on are used to label inputs and output. LOGIC SYMBOL OF THE “AND” GATE HOW DOES THE AND GATE WORK? ‘AND’ gates are like two or more switches in series. All the switches have to be closed (ON or value of 1) in order to make the lamp (output) turn on. If all the inputs are not ‘ON’, the output is ‘OFF’. TRUTH TABLE FOR “AND” GATE INPUT IN...
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