B) verbs

V. Read the text and entile it.

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 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.

Here are a few examples of Flash memory:

• Your computer's BIOS chip

• CompactFlash (most often found in digital cameras)

• SmartMedia (most often found in digital cameras)

• MemoryStick (most often found in digital cameras)

• PCMCIA Type I and Type II memory cards (used as solid-state disks in laptops)

• Memory cards for video game consoles

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 per cent 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 Erasing. 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 a traditional EEPROMs because instead of erasing one byte at a time, it erases a block or the entire chip, and then rewrites it.

Notes:

EEPROM (Electrically Erasable Programmable Read-Only Memory) – электрически стираемая память

VI. Say if the following statements are true or false. Correct the false statements.

1. Flash memory is used for easy and fast information storage.

2. Flash memory is considered a mechanical device.

3. The floating gate is only link to the row, or wordline.

4. Tunneling is used to alter the placement of atoms in the floating gate.

5. If the flow through the gate is greater than 50 per cent of the charge, it has a value of 0.

6. Flash memory works much faster than a traditional EEPROMs.

VII. Divide the text into logical parts and find the topical sentences in each part.

VIII. Give a short summary of text B.

Part C

I. Read the following text and entitle it.

1. Semiconductors have had a monumental impact on our society. You find semiconductors at the heart of microprocessor chip as well as transistors. Anything that’s computerized or uses radio waves depends on semiconductors.

2. Today, most semiconductor chips and transistors are created with silicon. You may have heard expressions like “Silicon Valley” and the “silicon economy,” and that’s why – silicon is the heart of any electronic or computer device.

3. A diode is the simplest possible semiconductor device, and is therefore an excellent beginning point if you want to understand how semiconductors work.

4. Silicon is a very common element – for example, it is the main element in sand and quartz. If you look “silicon” up in the periodic table, you will find that it sits next to aluminum, below carbon and above germanium.

5. Carbon, silicon and germanium (which, like silicon, is also a semiconductor) have a unique property in their electron structure – each has four electrons in its outer orbital. This allows them to form nice crystals. The four electrons form perfect covalent bonds with four neighboring atoms, creating a lattice. In carbon, we know the crystalline form as diamond. In silicon, the crystalline form is a silvery, metallic-looking substance.

6. Metals tend to be good conductors of electricity because they usually have “free electrons” that can move easily between atoms, and electricity involves the flow of electrons. While silicon crystals look metallic, they are not, in fact, metals. All of the outer electrons in a silicon crystal are involved in perfect covalent bonds, so they can’t move around. A pure silicon crystal is nearly an insulator – very little electricity will flow through it.

Notes:

II. Read the text and answer the questions.

1. What elements are considered to be semiconductors?

2. Why is silicon the heart of any electronic or computer device?

3. What part do semiconductors play in a computer technology?

III. Which paragraph contains the information about conductors of electricity having “free electrons”.

IV. Give the main points of the text in 5-6 sentences.

UNIT 6

Part A

Date: 2015-12-13; view: 521; Нарушение авторских прав