Summary ofChapter#1: Data StorageBits and Their Storage: Informationin form of 0’s & 1’s is called “bits” (short form ofBinary Digits).

The bit ‘0’ stands for False Value/Off state and theother one represents True Value/On state.             The operations that utilize thesevalues are known as “Boolean Operations”. Some basic operations of themeare OR, AND, NOT & XOR.

AND (Act as a multiplicative operator) OR (Act as an additive operator) NOT (Act as an inverse operator) XOR (Functions like OR except the outputs are same) Inputs Output Inputs Output Input Output Inputs Output 0     0 0 0     0 0 0 1 0     0 0 0     1 0 0     1 1 0     1 1 1     0 0 1     0 1 1 0 1     0 1 1     1 1 1     1 1 1     1 0    AND OR NOT NAND NOR   XNOR     XOR   Gate: A device which gives the outputof any Boolean Operations when the inputs are given, called Gate.Flip-Flops: Bistable gates/flip-flops, arethe types of circuits which is interconnected with logic gates in IntegratedChips(IC’s). They have two states On & Off or 1 & 0; they are oftenused for retrieving information. The outputs can change their states accordingto rules & remains in the state until a signal is received. It’s normallyused in Electronics, Computers & Communication Technologies. Hexa-Decimal Equivalents 23       22       21       20 (8Zeros   (4Zeros   (2Zeros   (1Zero & 8Ones) & 4Ones) & 2Ones) & 1One) Hexa-Decimal Equivalent 0       0       0       0 0 0       0       0       1 1 0       0       1       0 2 0       0       1       1 3 0       1       0       0 4 0       1       0       1 5 0       1       1       0 6 0       1       1       1 7 1       0       0       0 8 1       0       0       1 9 1       0       1       0 10=A 1       0       1       1 11=B 1       1       0       0 12=C 1       1       0       1 13=D 1       1       1       0 14=E 1       1       1       1 15=F Bit Patterns: In computers, we must deal with0’s & 1’s; sometimes they have patterns called Bit Patterns.            The 8-bit pattern 11100110 can bewritten as E6, obtained by dividing into groups of four & changing it withtheir Hexa-Decimal values.            16-bits pattern= (1111111001110011)2=(FE73)16.

Ø Along string of bits is quite often known as “Stream”.Main Memory: A computer device contains large number offlip-flops; each of them has a memory of single bit. This stocker refers tomachine’s main memory. A computer’s memory is in the form of cells, eachholds eight-bit (i.e. 1Byte). A typical memory cell contains only one Byte.Most Significant Bit (MSB)          0110110001        Least Significant Bit (LSB)Acomputer’s main memory is quite often refers to Random Access Memory (RAM).

 Every individual cell has a unique name,known as address.            DRAM (Dynamic RAM) or SDRAM(Synchronous DRAM) is used in illusion to DRAM that is decreases the timeelapsed to retrieve things from memory chips.Measuring Memory Capacity: 210=1024, it isclosed to 1000, so that’s why it is neglected as Kilo.1KB                                         1KiloByte                                            1024Bytes1MB                                        1MegaByte                                          1024KiloBytes1GB                                         1GigaByte                                            1024MegaBytes1TB                                         1TeraBytes                                          1024GigaBytesMass Storage: Secondary/Mass Storage devices are additional memorydevices, their different classes are:Magnetic System:Normally called HardDisk-Drive/HDD (Magnetic Disk), has a spinning disk coated with magnet isused to store data.

It is a fixed disk & having non-volatile memorythat can store & retrieve data on computer.Optical System: It is the storage method inwhich data can be hold by a reflective disk by creating marks on it. Usually aLaser Beam is used to detect/read data by checking variations on thespinning disk. Some examples are:CD-(Compact Disk)                                        600-700MBCD-DA(Compact Disk-Digital Audio)                        approx.

74 minute audio or beyond (decreased pitch) DVD(Digital Versatile Disk)                           approx.4.7 GBBD(Blu-Ray Disk)                                          Overfive times Capacity of DVD’sFlash Drives: It is a kind of storage, unlikethe HDD or Optical Devices, it has no moving parts. Normally used to transferor save data from Computers, Digital Cameras etc. Some examples are:SD                   Secure DigitalSDHC              SD- High CapacitySDXC              SD-Extended CapacityRepresenting Information in Bit Patterns: Asall we know that computer only can understand binary language in contrast toHuman Language, that is why it retrieves information/data in term of bits “Program” converts it the human readable form. (Things theyrepresent)Text: ASCII (American StandardCode for Information Interchange) uses bit-patterns of various lengths torepresent several things. The 7-bit pattern is used to represent lowercase & upper case alphabets of English language, digits 0-9, punctuationsymbols etc.

They add ‘0’ at the most significant end to make asymbol/character 8-bit. For example:Ø (.)is assigned with the binary value 00101110Ø (A)is assigned with the binary value 01000001Ø (a)is assigned with the binary value 01100001Representing Numeric Values: Binary notations uses value 0,1 to represent instead of using numbers 0-9. Their lengths are shown in thetable below.

Length of bit (b) Number of possible value (N) Length of bit (b) Number of possible value (N) Length of bit (b) Number of possible value (N) 1 2 4 16 7 128 2 4 5 32 8 256 3 8 6 64 9 512 By thetable we derive a formula, i.e. 2b=N. By the help of this formula wecan assign numeric value in the bit-strings.Representing Images: For image representation, computertakes it as a collection of dots (Pixels). Each of the pixels is encrypt& the image is taken as collection of Encrypted Pixels that is called Bit-map.            The method on which a picture is encoded/encryptedin a bit-map depends over the application & the format ofimage.

Representing Sound: For representing sound, it iscompulsory to convert into binary code, for computers to process it. Todo this we usually record/capture sound by mice (microphone) & thenconverting it into “Digital Signals”.Afterthat the sound’s wave altitude & longitude (amplitude) takenas numeric values & then it is changed by their binary equivalents.The Binary System:Binary Notations: Suppose a number in base 10system (Commonly used system), like 8925, in this number we knows the number’5′ is one’s position, number ‘2’ is in ten’s position, number ‘9’ is in thehundred’s position and the number ‘8’ is in the thousand’s position.  The pattern ‘8925’ can also be written as(8*thousand) + (9*hundred) + (2*ten) + (5*1), further we can technicalizethat (8*103) + (9*102) + (2*101) + (5*100).            In the same manners we do same thingin binary system as shown above.

In the system of ten we use ’10’ as base; samein the binary system we take ‘2’ as base. For example:(1011101)2=(1*26) + (0*25) + (1*24) + (1*23) +(1*22) + (0*21) + (1*20) = (93)10Algorithm for converting apositive integer into Binary System: Step 1:Divide the integer by ‘2’, & obtain the remainder.Step 2:Keep dividing the newest quotient by ‘2’ & record the remainders, until thequotient of ‘0’ is obtained.Binary Addition Facts: 0 + 0 0 0 + 1 1 1 + 0 1 1 + 1 0 (with carry of 1) Fractions: In fractions, we use “Radix Point”in the same manners as decimal notations.

The first position after decimal tothe right gaining the quantity 1/2=1/21, second one with 1/4=1/22,third one with 1/8=1/23 so one. For example:110.0110=(1*22)+ (1*21) + (1*20). + (0/2) + (1/4) + (1/8) + (1/16)Storing Integers: The system in which Integer is to be represented is “Two’sCompliment notation”.

It is the most popular & commonly used system. Intoday’s apparatus, each integer is represented in a pattern of 32bits.In this system, the left most bit shows the sign of the value. That is why itis often known as “Sign Bit”.Ø Negative values sign bit is 1.Ø Non-Negative values sign bit is 0.Storing Fractions: To store fractions, “FloatingPoints” are normally used.Programming & Data: Programming is a key to lead from formationto executable computer programs.

In programming languages, Python is a commonlyknown language, which enables us for general purpose programming. It isan interpreter, high-level & object oriented programming language.Variables: In any programming language, avariable is used to store/contain data. It has a value assigned byuser/coder, which depends over the condition or information ofprogram. Its value may be sometimes known or sometimes unknown.Debugging:Debugging is refers to a process in whichwe can find/detect problems/errors in a code & then resolved. Thereare many kinds of errors; some of them are shown below:Syntax Error: (Mistake in typing code)Run-Time Error: (Errors occurs is executingtime)Semantic Error: (Due to miss-considering theintentions of a program)Data Compression: A process/technique in which the data size isreduced is called “Data Compression”.

It has two types:Lossless: In which the information is notloosed in Compression Process.Lossy: In which we leads to looseinformation during the process.Image Compression: As we have discussed images areencoded using bit maps, unfortunately their bit maps are often larger thanexpectations.

To reduce their bit maps we use “Image Compression Technique”in which an image size is reduced, without degrading their quality.Compressing Audio/Video: To compress audio/video, thewidely used standards are developed by MPEG (Motion Picture ExpertGroup). Theycompress a variety of encoding standard for different standard; theirtechniques are beyond the scope of text.Ø Inaudio they reduce their bit-rate.Ø Invideo they reduce their frame-rate.Communication Errors: When data travels to anotherplace, from a computer device to another server, machine in a building/acrossthe world, some errors occurs when the data travels through channels.            To detect or resolve these errors,many techniques are available; a simple method is described below:Parity Bit & Error CorrectingCode: It isalso known as Check Bit, A parity bit is added to a binary number stringto confirm that either it is odd or even.

It is a simplest method for errordetecting codes.            Parity bit enables us to detect anerror, but it can’t help in correcting these errors. To resolve it we usepatterns of codes & compare them with next received codes until we findone, which is within the distance from received pattern.

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