III. Join the sentences with the proper variant in the right column.

1. Write back cache holds off writing a) although rare and expensive.

to the hard disk

2. A more sophisticated cache memory keeps b) ranges in size from 64K to 1M.

3. The built-in cache memory c) an alternative architecture to direct

mapped memory.

4. Associative cache describes d) until there is a lull in CPU activity.

5. Cache SRAM at speeds up to 8ns e) a count of number of accesses made

has recently become available, to each variable.

 

6. The capacity of external cache f) is located inside the CPU.

 

IV. Answer the following questions.

1. What was the reason of the cache memory introduction?

2. What are the functions of the control unit in case of cache memory?

3. What can a more sophisticated cache memory do?

4. What is called a cache memory controller?

5. What types of cache memory help to speed up the computer’s performance?

6. What cache holds off writing to the hard disk until there is a lull in CPU activity?

7. What cache describes an alternative architecture to direct mapped memory?

8. What cache SRAM is generally used for system boards?

 

Read the text.

 

In order to make room for the new entry on a cache miss, the cache generally has to evict one of the existing entries. The heuristic that it uses to choose the entry to evict is called the replacement policy. The fundamental problem with any replacement policy is that it must predict which existing cache entry is least likely to be used in the future. Predicting the future is difficult, especially for hardware caches which use simple rules amenable to implementation in circuitry, so there are a variety of replacement policies to choose from and no perfect way to decide among them. One popular replacement policy, LRU, replaces the least recently used entry.

When data is written to the cache, it must at some point be written to main memory as well. The timing of this write is controlled by what is known as the write policy. In a write-through cache, every write to the cache causes a write to main memory. Alternatively, in a write-back or copy-back cache, writes are not immediately mirrored to memory. Instead, the cache tracks which locations have been written over (these locations are marked dirty). The data in these locations is written back to main memory when that data is evicted from the cache. For this reason, a miss in a write-back cache will often require two memory accesses to service: one to read the new location from memory and the other to write the dirty location to memory. This is also called batch mode.

There are intermediate policies as well. The cache may be write-through, but the writes may be held in a store data queue temporarily, usually so that multiple stores can be processed together (which can reduce bus turnarounds and so improve bus utilization).

The data in main memory being cached may be changed by other entities, in which case the copy in the cache may become out-of-date or stale. Alternatively, when the CPU updates the data in the cache, copies of data in other caches will become stale. Communication protocols between the cache managers which keep the data consistent are known as cache coherence protocols.

 

Find the English equivalents in the text.

Витісняти (дані із кеш-памяті)

Методика заміщення

Алгоритм видалення елементів, які найдовше не використовувались

Кеш із прямим записуванням

Кеш із зворотним записом

Змінені (дані)

Застарілі (дані)

Протоколи синхронізації кеша

 

Flash Memory Devices

 

A memory card, also known as a smart card or multimedia card, is one of the external storage media of a personal computer and multifunction terminal electronic equipment. A semiconductor memory card has an internalized non-volatile memory, which is accessed by a connected device, enabling the semiconductor memory card to be used as a recording medium. The most widely used solid-state memory devices include flash-memory chips configured on a small removable memory card, and are commonly referred to as flash memory cards. A flash memory is a type of EEPROM that can be erased and reprogrammed in blocks instead of one byte at a time.

Compared with other memory devices, flash memory devices have many advantages, which include their non-volatility, speed, ease of erasure and reprogramming, small physical size and related factors. A flash memory is a semiconductor memory showing low power consumption and maintaining stored information even when power is off. Flash memory devices typically use a one-transistor memory cell that allows for high memory densities, high reliability, and low power consumption. Flash memories can program, read and erase data for multiple times, and data stored therein can be maintained even if the power applied thereto is off. Flash memory devices do not require refreshing and can store data indefinitely after the power is removed. Flash memory devices are applicable for multiple operations of data writing, reading and erasing. Flash memory devices have achieved a commercial success in an electronic industry because they are able to store data for a relatively long time even without a power supply. Flash memory has been widely used for high volume data storage in devices such as personal computers, personal digital assistants (PDA's), cellular phones, digital TV, digital camcorder, digital camera, and MP3 players.

Flash memory brings convenience to information industries for storage of data. The multimedia network technology has developed to the extent that digital contents such as video information are distributed via a communication network such as the Internet. For example, traditional film cameras have been widely replaced by digital cameras capable of recording images that may be directly downloaded to and stored on personal computers. The pictures recorded by digital cameras can easily be converted to common graphics file formats such as joint photographic experts group (JPEG), graphic interchange format (GIF) or bitmap (BMP), and sent as e-mail attachments or posted on web pages and online photo albums. Many digital cameras are also capable of capturing short video clips in standard digital video formats, for example, moving picture experts group (MPEG), which may also be directly downloaded and stored on personal computers or notebook computers. Small flash-memory cards have been designed that have a connector that can plug into a specialized reader, such as for compact-flash, secure-digital, memory stick, or other standardized formats.

Flash memory cards are formed in card shapes in which memory chips are sealed in card type outer shells. Flash memory cards are designed in many standards such as an SD (Secure-Digital) card, a multimedia card, a Smartmedia, a compact flash (CF) card, and a memory stick. SD card is an extension of the earlier MultiMediaCard (MMC) format. SD cards are hot-swappable, allowing the user to easily insert and remove SD cards without rebooting or cycling power. Information equipment such as personal computers, PDAs, digital cameras, and cellular phones are generally provided with a card slot for mounting a flash memory card.

More recently, flash memory cards are being designed that contain a USB connector which is constructed that the flash memory card is insertable and extractable in a direction parallel to a mounting wiring board through the slot port. USB flash-memory drives and devices have been developed to transport data from one host to another, replacing floppy disks. A USB-flash card can have a capacity of more than ten floppy disks in an area not much larger than a large postage stamp.

 

Comments:

smart card картка пам’яті, мікропроцесорна картка

refreshing відновлення змін зображення//заміна частини або

всього зображення на екрані за допомогою

виводу нових графічних даних;

регенерація//періодичне пере записування

зображення на дисплеї для оперативного

відображення

MP3 player технологія ущільнення звуку МР3//формат для

зберігання та пересилання сильно ущільнених

цифрових музичних та аудіофайлів

JPEG (Joint Photographic об’єднана група експертів із машинного

Experts Group) оброблення фотографічних зображень//

робоча група зі стандартів цифрових

відео- та мультиплікаційних зображень; алгоритм

ущільнення нерухомого зображення

GIF Graphics Interchange формат обміну графічними даними

Format BMP (від bitmap) формат ВМР//стандартний формат растрових

графічних файлів

reboot перезавантаження; перезавантажити// перезапуск

комп’ютера з клавіатури

EEPROM електричний програмований ПЗП, який

(також E2PROM) дозволяє стирати; пам’ять, яка електрично Electrically Erasable стирається

Programmable

Read-Only Memory