Part 1 basic vocabulary

1   ...   10   11   12   13   14   15   16   17   ...   20

When you listen to the news, you hear about many different forms of electronic infection. The most common are:

• 
  Viruses - A virus is a small piece of software that piggybacks on real programs. For example, a virus might attach itself to a program such as a spreadsheet program. Each time the spreadsheet program runs, the virus runs, too, and it has the chance to reproduce (by attaching to other programs) or wreak havoc.
  
• 
  E-mail viruses - An e-mail virus moves around in e-mail messages, and usually replicates itself by automatically mailing itself to dozens of people in the victim's e-mail address book.
  
• 
  Worms - A worm is a small piece of software that uses computer networks and security holes to replicate itself. A copy of the worm scans the network for another machine that has a specific security hole. It copies itself to the new machine using the security hole, and then starts replicating from there, as well. For example, the Code Red worm took advantage of vulnerabily in the Microsoft Internet Server Application Program Interface (ISAPI) service and replicated itself over 250,000 times in approximately nine hours on July 19, 2001. The Slammer worm (which caused mayhem in January 2003) exploited a hole in Microsoft's SQL server.
  
• 
  Trojan horses - A Trojan horse is simply a computer program. The program claims to do one thing (it may claim to be a game) but instead does damage when you run it (it may erase your hard disk). Trojan horses have no way to replicate automatically.
  

The latest thing in the world of computer viruses is the e-mail virus, and the Melissa virus in March 1999 was spectacular. Melissa spread in Microsoft Word documents sent via e-mail, and it worked like this:
Someone created the virus as a Word document uploaded to an Internet newsgroup. Anyone who downloaded the document and opened it would trigger the virus. The virus would then send the document (and therefore itself) in an e-mail message to the first 50 people in the person's address book. The e-mail message contained a friendly note that included the person's name, so the recipient would open the document thinking it was harmless. The virus would then create 50 new messages from the recipient's machine. As a result, the Melissa virus was the fastest-spreading virus ever seen! It forced a number of large companies to shut down their e-mail systems.
The ILOVEYOU virus, which appeared on May 4, 2000, was even simpler. It contained a piece of code as an attachment. People who double clicked on the attachment allowed the code to execute. The code sent copies of itself to everyone in the victim's address book and then started corrupting files on the victim's machine. This is as simple as a virus can get. It is really more of a Trojan horse distributed by e-mail than it is a virus.
The Melissa virus took advantage of the programming language built into Microsoft Word called VBA, or Visual Basic for Applications. It is a complete programming language and it can be programmed to do things like modify files and send e-mail messages. It also has a useful but dangerous auto-execute feature. A programmer can insert a program into a document that runs instantly whenever the document is opened. This is how the Melissa virus was programmed. Anyone who opened a document infected with Melissa would immediately activate the virus. It would send the 50 e-mails, and then infect a central file called NORMAL.DOT so that any file saved later would also contain the virus! It created a huge mess.
Ex. 2. Which of the following statements are true and which are false?

1. 
   A virus can piggyback on a spreadsheet document. T/F
   
2. 
   An e-mail virus replicates itself a dozen times in the victim’s address book. T/F
   
3. 
   A worm takes advantage of a security hole in a recipient’s computer. T/F
   
4. 
   The aim of a worm is to wreak havoc on a specific computer. T/F
   
5. 
   Trojan horse pretends to be something that it is not and it can’t replicate itself. T/F
   
6. 
   E-mail viruses were among the earliest known types of electronic infection. T/F
   
7. 
   The Melissa virus was one of the most harmless. T/F
   
8. 
   The ILOVEYOU virus was triggered off as soon as you single clicked on the attachment of an e-mail message. T/F
   
9. 
   The auto-execute feature of VBA is useful and harmless. T/F
   
10. 
    You don’t have to open a document to make Melissa work. T/F
    

Ex. 3. Translate from Russian into English

1. 
   Вирус может размножиться, прикрепляясь к другим программам, или нанести ущерб.
   
2. 
   Вирус Красный код (Code Red) использовал уязвимость интерфейса прикладного программирования в Майкрософт офисе.
   
3. 
   Кто-то создал и загрузил вирус как документ Word на сайт новостей Интернет.
   
4. 
   Вирус Мелисса вынудил ряд Интернет компаний закрыть свои почтовые серверы.
   
5. 
   ЯЛЮБЛЮТЕБЯ более похож на троянца, распространяемого через электронную почту, чем на обычный почтовый вирус.
   

16 Flash Basics (after Jeff Tyson)
Ex.1 Study the active vocabulary

Electronic memory comes in a variety of forms to serve a variety of purposes. Flash memory is used for easy and fast information storage in such devices as digital cameras and home video game consoles. It is used more as a hard drive than as RAM. In fact, Flash memory is considered a solid state storage device. Solid state means that there are no moving parts -- everything is electronic instead of mechanical.

Flash memory is a type of EEPROM chip. It has a grid of columns and rows with a cell that has two transistors at each intersection. The two transistors are separated from each other by a thin oxide layer. One of the transistors is known as a floating gate, and the other one is the control gate. The floating gate's only link to the row, or wordline, is through the control gate. As long as this link is in place, the cell has a value of 1. To change the value to a 0 requires a curious process called Fowler-Nordheim tunneling.

Tunneling is used to alter the placement of electrons in the floating gate. An electrical charge, usually 10 to 13 volts, is applied to the floating gate. The charge comes from the column, or bitline, enters the floating gate and drains to a ground.

This charge causes the floating-gate transistor to act like an electron gun. The excited electrons are pushed through and trapped on other side of the thin oxide layer, giving it a negative charge. These negatively charged electrons act as a barrier between the control gate and the floating gate. A special device called a cell sensor monitors the level of the charge passing through the floating gate. If the flow through the gate is greater than 50 percent of the charge, it has a value of 1. When the charge passing through drops below the 50-percent threshold, the value changes to 0. A blank EEPROM has all of the gates fully open, giving each cell a value of 1.

The electrons in the cells of a Flash-memory chip can be returned to normal ("1") by the application of an electric field, a higher-voltage charge. Flash memory uses in-circuit wiring to apply the electric field either to the entire chip or to predetermined sections known as blocks. This erases the targeted area of the chip, which can then be rewritten. Flash memory works much faster than traditional EEPROMs because instead of erasing one byte at a time, it erases a block or the entire chip, and then rewrites it.

You may think that your car radio has Flash memory, since you are able to program the presets and the radio remembers them. But it is actually using Flash RAM. The difference is that Flash RAM has to have some power to maintain its contents, while Flash memory will maintain its data without any external source of power. Even though you have turned the power off, the car radio is pulling a tiny amount of current to preserve the data in the Flash RAM. That is why the radio will lose its presets if your car battery dies or the wires are disconnected.

1   ...   10   11   12   13   14   15   16   17   ...   20

При копировании материала укажите ссылку © 2024
контакты
rykovodstvo.ru