Perfect Computer Notes

10 Differences Between Impact Printers and Non Impact Printers Differences Between Impact and Non-Impact Printers Impact Printers Non-Impact Printers 1 It produces print on paper by striking mechanism. It produces print on paper with a non-striking mechanism 2 It uses pins, hammers or wheel to strike against an inked ribbon to print on a paper.. It uses laser, spray of special ink, or heat and pressure to print on paper.  3 Normally impact printers use continuous paper sheet.  Non-Impact printers normally use individual paper sheets. 4 Impact printers are normally less expansive. Non-Impact printers are more expansive. 5 Print quality of impact printers is lower than those of non impact printers.. Print quality of Non-Impact printers is higher than those of impact printers. 6 Impact printers use spec...

Printers A printer is an output device that prints characters, symbols and graphics on paper. The printed output is called hard copy. Printers produce permanent documents. Print resolution is commonly measured in dots per inch (dpi). A printer with higher print resolution, that is, dpi will produce higher quality print outs, but it will cost higher too. Types of Printers Depending upon the mechanism of printing, there different types of printers, as follows: 1) Impact Printers 2) Non-Impact Printers 1. Impact Printers An impact printer works like a typewriter. It prints characters or images by striking a print hammer , a typeface or pins against paper and inked ribbon. We can say that impact printers do hit or impact an inked ribbon to print on a paper. Since, impact printers produce print outs by striking mechanism, they make a lot of noise, too. Print quality of impact printers is lower than print quality of non-impact printers. Printing cost or impact printers is l...

Difference between CRT monitors and Flat Panel (LCD) Monitors Differences between CRT Monitors and Flat-panel (LCD) Monitors CRT Monitors Flat-panel (LCD)Monitors 1 CRT monitors are low-priced and more economical than flat-panel (LCD) monitors. Flat-panel monitors are more costly than CRT monitors. 2 Commonly, CRT monitors are used with personal computers. In the beginning LCD monitors were used in lap top or note book computers, PDAs and smart phones. But now they available for PCs, too.  3 CRT monitors use Cathode Ray Tube (picture tube) Technology to show text and graphics on screen. Flat-panel monitors use LCD - Liquid Crystal Display technology or Gas Plasma technology. 4 CRT monitors need more power. LCD monitors uses less energy than CRT monitors. 5 CRT monitors take more space on desk. LCD monitors take less space on desk top. 6 ...

Monitor Monitor is the most familiar output device. It is a display screen or visual display unit to show text and graphics to computer user. Common monitors look like a TV. Latest monitors are flat panel monitors like LCD monitors. Although LCD monitors are more costly than general old fashioned monitors called CRT monitors, they are light weight and don't emit radiations harmful to eyes. Types of Monitors There are the following main types of Monitors: 1. CRT Monitors 2. Flat Panel Monitors 3. Touch Screen Monitors 1. CRT Monitors CRT stands for Cathode Ray Tube. CRT monitors use electronic beam gun to produce text and images. These electronic guns fire a beam of electrons on very tiny phosphorus dots on internal surface of screen. In color CRT monitors there are three electron beam guns for Red, Green and Blue colors. CRT monitors take more space on desk. These are heavier than flat panel monitors. CRT monitors emit radiations which are harmful for human eyes...

What are commonly used units of measuring storage? Bit Bit is a short for Binary Digit. 0 and 1 are the only binary digits. Bit is the smallest unit of measuring storage capacity. A bit can hold a 0 or 1. Byte A combination of 8 bits is called a Byte. A byte can hold one character. 1 Byte = 8 bits Kilobyte (KB) 1024 bytes make one kilo byte. Kilo Byte is denoted by KB. 1 KB = 1024 Bytes Megabyte (MB) 1024 Kilo bytes make one mega byte. Mega Byte is denoted by MB. 1 MB = 1024 KB Gigabyte (GB) 1024 mega bytes make one Giga byte. Giga Byte is denoted by GB.  1 GB = 1024 MB Terabyte (TB) 1024 Giga bytes make one Tera byte. Tera Byte is denoted by TB.  1 TB = 1024 GB Petabyte (PB) 1024 Tera Bytes make one Peta byte. Peta Byte is denoted by PB.  1 PB = 1024 TB Exabyte (EB) 1024 Peta bytes make one Exa byte. Exa Byte is denoted by EB.  1 EB = 1024 PB

What are different security protocols for e-payment security schemes? 1. SSL Protocol (Secure Sockets Layer Protocol) SSL (Secure Sockets Layer) is the standard security protocol for establishing an encrypted link between a web server and a browser. This link ensures that all data passed between the web server and browsers remain private and integral. SSL is used by millions of websites in the protection of their online transactions with their customers. SSL or Secure Sockets Layer is a security protocol created by Netscape that has become an international standard on the Internet for exchanging sensitive information between a website and the client computer. SSL technology is embedded in all popular browsers and engages automatically when the user connects to a web server that is SSL-enabled. It's easy to tell when a server is using SSL security because the address in the URL window of your browser will start with https. The "s" indicates a secure connection....

Explain E-payment Security Schemes Following are the e-payment security schemes 1) Encryption 2) Certificates & Certificates Authority (CA) 3) Digital Signature 4) Digital Envelop 5) Message Digest 6) Transaction Certificates and Time Stamp (1) Encryption Encryption refers to changing a message into unreadable form. Later the encrypted message can be converted into readable form by Decryption. There are two types of Encryption (A) Secret Key Encryption/Private Key Encryption In this scheme, same key called secret key is used by sender and receiver for Encryption (Making message unreadable) & Decryption (Getting original message). Data Encryption Standards (DES) is the most widely used algorithm for secret key/private key encryption scheme. (B) Public Key Cryptography It is Also known as asymmetric Encryption. It uses two different keys (1) Private Key (2) Public Key. The receiver sends his public key to sender. The sender encrypts message with thi...