17 Mark马克



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What is recursion?In math, recursion is a common concept. It means that a function is defined in terms of itself. For example, the factorial function is defined:f(n) = n * f(n-1)f(0) = 1f(n) is de...

2020-02-19 11:56:58

Possible ways in which malware can be introduced

The introduction of malware is associated directly with the activities of legitimate users of a system. Examples are:Attaching portable storage deviceFew decades ago, when internet was not a norm, ...

2020-02-10 16:51:54

Computer Malware

A malware is a software that is designed to get on a computer and cause harms to the information there or problems with the way it works. Malware is the colloquial name for malicious software. Compute...

2020-02-09 22:46:16

Computer mouse

The use of mouse became a norm with the creation of the Graphic User Interface. GUI introduced windows, menus, dialogs and other features to the User Interface (UI), which totally transformed the func...

2020-02-06 23:46:02

Stepwise Refinement

What is stepwise refinement?The verb refine means to improve a method, plan, system etc., gradually making slight changes to it. The word stepwise means to do something in a series of distinct stage...

2020-02-04 18:50:38


Key pointsA video is simply a succession of still images/sequence of still images.Frame rate: the number of frames displayed per second, usually expressed in FPS.The resolution of a video is the n...

2020-02-03 17:34:08

Input and output of sound

Key pointIn physics, sound is a vibration that propagates as an acoustic wave through a transmission medium, such as a gas, solid or liquid.In computer science, all type of information has to be in...

2020-02-01 14:19:31

The internal operation of a laser printer

The core principleThe core principle is the physical law: opposite charges attract, like charges repel.Main componentsA drum, photoreceptor drum, photosensitive drumThe drum is coated with photos...

2020-01-31 22:25:55

Digital Certificate

Previously, in digital signature, we mentioned that it is possible that an attacker may pretend to be someone else, generate the pair of keys, make a fake message, generate a digest using hash functio...

2020-01-31 13:58:31

Digital signature

In asymmetric encryption, the sender and the recipient, each has a pair of keys, a public key and a private key. The public key and private key are mathematically linked together. If a message is encr...

2020-01-30 23:19:22

Symmetric encryption VS Asymmetric encryption

Encryption is a process of encoding the plaintext with a key to generate ciphertext so that the plaintext is unreadable. In such a way, the confidentiality of the original message is guaranteed.Decr...

2020-01-30 12:33:23

Encryption fundamentals

Key Terms   Plaintext:data before encryption.   Ciphertext: the result of applying encryption algorithm to data.  &amp...

2020-01-29 17:00:16

Software engineering code of ethics recommended by ACM/IEEE

Software engineers shall commit themselves to making the analysis, specification, design, development, testing and maintenance of software a beneficial and respected professional. In accordance with t...

2020-01-28 12:01:44

Compression techniques

Why are compression techniques necessary?Previously, we talked about the representations of number, text, image, sound, video in binary form (Chapter 1). The file size of data is always a major conc...

2020-01-22 11:34:26

Vector graphic VS bitmap image

Vector graphicA vector graphic file contains a drawing list. The list contains a command for each object included in the image The objects are defined by geometrical formula and associated propert...

2020-01-18 09:53:28

Packet switching VS Circuit switching

Packet switchingData to be transmitted is divided into fix-sized blocks called 'packets' or 'datagrams. These packets are then transmitted through the network independently of each other. The pack...

2020-01-16 10:07:37

The differences between World Wide Web and Internet

WWW consists of content organized as web pages. The Web pages are available across the Internet from web servers; HTTP protocol is use to transfer the web pages from server to client; The Internet is...

2020-01-12 20:43:06

Compiler VS Interpreter

Benefits of a compiler:A compiler creates object code - that is, an executable file. Compile program execute faster than interpreted code The compiler software is not needed at run time: once comp...

2020-01-09 10:26:16

The advantages of Solid state memory(Solid State Drive)

Solid state memory has many advantages over magnetic disk storage:There are no moving components//mechanical parts They are typically more resistant to physical shock//robust,durable They run sile...

2020-01-09 10:23:21

Dynamic RAM VS Static RAM

Dynamic RAM is made up of capacitors. The capacitor holds a high or low charge ( to represent 1 or 0)//Static RAM is made up of flip-flops The capacitors of DRAM leak electricity, so recharging is re...

2020-01-09 10:21:40


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