IV. Answer the following questions.
1. What is memory used for?
2. What types of memory are mentioned in the text?
3. What is the role of RAM?
4. What is PROM famous for?
5. What type of memory uses a capacitor to store data?
6. What type of memory uses magnetic charges to store data?
7. What is the typical read/write time of DRAM?
V. Decide whether the following statements are true or false. It they are false, correct them.
1. RAM is used for writing data only.
2. Memory is the essential element of modern electronics.
3. DRAM is a form of semiconductor memory which isn’t used in PCs and workstations.
4. MRAM is a volatile type of RAM memory.
5. EEPROM retains the contents of the memory when the power is turned off.
VI. Which words in the text have the same meaning as?
primary, fast speed, principle, essential, need, related to, complex, fast, can be used, can be classified, delete, keep/hold, information, from time to time, besides, manufacture/do/make.
VII. Here are the answers, make out the questions.
1. into two main categories
2. is called RAM
3. is a non-volatile RAM memory technology
4. flash memory
5. using an electrical voltage
VIII. Match each term with its proper definition.
1. chip
2. video
3. storage medium
4. firmware
5. control unit
6. main memory
7. operating system
8. cache
a) the programs and routines which allow a computer to operate
b) the electronic memory that holds the programs and data being used
c) a CPU component which coordinates all parts of the computer system
d) fast memory used to temporarily store frequently-used data
e) an electronic integrated circuit in a small package
f) a material used for storing programs and data
g) permanent software instructions contained in the ROM
h) signals containing picture information
IX. What do the following abbreviations stand for?
EPROM, EEPROM, MRAM, DRAM, SRAM, SDRAM, ROM, RAM.
UNIT 7. FLASH MEMORY
I. Practise reading the following words.
invented, camera, potential, random, storage, process, firmware, endurance, access, content, allow, sequential, numerous, secure, format, volatile, wire, media, erase, presumably, layer, released, gigabit, manufacture, assumption, transfer, digital, solid-state, storage, resistance, portable, advantage.
II. Before reading the text try to answer these questions.
1. What do you use flash memory cards for?
2. What is the capacity of your flash memory cards?
3. What is the difference between flash memory cards and hard disk drives?
III. Read and translate the following text into Ukrainian.
Flash memory
Flash memory is non-volatile computer memory that can be erased and reprogrammed. This technology is primarily used in memory cards and USB flash drives for general storage and data transfer between computers and other digital devices. It is a specific type of EEPROM (Electrically Erasable Programmable Read-Only Memory) that is erased and programmed in large blocks. Flash memory has become the dominant technology wherever a significant amount of solid-state storage is needed. These applications include PDAs, laptop computers, digital audio players, digital cameras and mobile phones (see figure 7). Flash memory has also gained popularity on the game console market, where it is often used instead of EEPROMs or battery-powered SRAM for saving data in games.
Figure 7. Summary figure global value sales of overall memory to semiconductor device manufacturers and end users, 2007-2014 ($ millions)
Flash memory is non-volatile, i.e., no power is required to maintain the information stored in the chip. In addition, flash memory offers fast access time and better kinetic shock resistance than hard disks. These characteristics explain the popularity of flash memory in portable devices. When flash memory is packaged in a «memory card», it is enormously durable, being able to withstand intense pressure, extremes of temperature and even immersion in water. The term «EEPROM» is generally used to refer to non-flash EEPROM which is erasable in small blocks, typically bytes. The large blocks are used in the process of flash memory erasing and give a significant speed advantage over old-style EEPROM because erase cycles are slow.
Flash memory was invented by Dr. Fujio Masuoka while working for Toshiba in 1984. According to Toshiba, the name «flash» was suggested by Dr. Masuoka's colleague, Mr. Shoji Ariizumi, because the erasing process of the memory contents reminded him a flash of a camera. Dr. Masuoka presented the invention at the 1984 International Electron Devices Meeting (IEDM) held in California. In 1988 Intel saw the massive potential of the invention and introduced the first commercial NOR type flash chip. NOR-based flash has long erase and write time, but provides address and data buses, allowing random access to any memory location. This makes it a suitable replacement for older ROM chips, which are used to store program code that rarely needs to be updated, such as a computer's BIOS or the firmware. Its endurance is 10,000 to 1,000,000 erase cycles. NOR-based flash was the basis of early flash-based removable media; CompactFlash was originally based on it, though later cards moved to less expensive NAND flash. Toshiba announced NAND flash at ISSCC in 1989 (see table 2).
|
Type |
NOR |
NAND |
|
arrangement |
connected in parallel, allowing extremely fast random access |
Connected in serial and required fewer data lines |
|
chip capacity |
called “Code Flash”, with lower chip capacity than NAND, main market capacity is about 512MB |
called “Data Flash”, with larger chip capacity and density, main capacity is 2GB |
|
addressing type |
linear-addressed device |
non-linear addressed device |
|
read/write speed |
higher reading speed than NAND |
higher writing and erasing speed than NOR flash |
|
manufacturers |
Intel, AMD, Fujitsu, and Sharp (set-top boxes, game machines) |
Toshiba, Samsung, and SanDisk (digital cameras, mp3 players) |
Table 2. NOR and NAND characteristics
This technology has faster erase/write time and allows greater storage density and lower cost per bit than NOR flash. Also, it has up to ten times the endurance of NOR flash while the I/O interface of NAND flash does not provide a random-access external address bus.
This makes NAND flash an unsuitable replacement for programmable ROM. NAND flash is similar to such secondary storage devices as hard disks and optical media and, thus, it is very suitable to use in mass-storage devices, e.g., memory cards. The first NAND-based removable media format was SmartMedia, and after it a lot of others have followed, including MultiMediaCard, Secure Digital, Memory Stick and xD-Picture Card. The common feature of the new generation of memory card formats (RS-MMC, miniSD and microSD and Intelligent Stick) is extremely small form factor. For example, the microSD card has an area of just over 1.5 cm², with a thickness of less than 1 mm; microSD capacities range from 64MB to 32GB.
Flash memory cards are available at different speeds. Some are specified the approximate transfer rate of the card such as 2 MB per second, 12 MB per second, etc. However, other cards are simply rated 100x, 300x, 200, etc. For these cards the base assumption is the 1x is equal to 150 kilobytes per second. This was the speed at which the first CD drives could transfer information, which adopted as the reference speed for flash memory cards. The most common cause of data corruption is removal of the flash memory device while data is being written to it.
Answer the following questions.
1. What type of memory is called flash?
2. What is the origin of the term «flash memory»?
3. Who invented flash memory?
4. When was the first commercial NOR type flash chip introduced?
5. What is the main difference between NOR and NAND types of flash memory?
6. Why is flash memory so popular?
7. In what devices can flash memory be used?