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Primary Storage PowerPoint Presentation
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Primary Storage

Primary Storage

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Primary Storage

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  1. Primary Storage

  2. Memory • This is located on the motherboard so that data can travel quickly to and from the cpu. • Data can be stored in the memory and it can be accessed to be read from, written to or processed. There are several types of computer memory: • RAM (Random Access Memory) or Main Memory • ROM (Read-only Memory) • Hybrid Memory

  3. RAM – Random Access Memory • These memory chips store the temporary operating instructions for the computer, its programs and the data. The CPU receives the instructions and data to perform its job from RAM. • This memory serves several functions: • A working storage area which holds data currently being processed. • A working storage area where output data can be held before it is transferred to the printer or some other output device. • It would hold the program currently being executed.

  4. Advantage The computer can access data very quickly from RAM. Disadvantage It is volatile – the data held in RAM is lost when the computer is turned off or malfunctions. N.B. It is important to store data on a storage device, so that data can be stored permanently.

  5. ROM – Read-only Memory • This is an integrated circuit programmed with specific input/output instructions for the computer. These instructions can be read, but they cannot be changed or altered (non-volatile). • There are five basic ROM types: • ROM • PROM • EPROM • EEPROM • Flash Memory

  6. Advantages and Disadvantages of ROM Advantage The data stored is permanently Disadvantage The data stored cannot be easily modified or altered.

  7. PROM – Programmable ROM • Characteristics: • Contents can not be changed once PROM is programmed. • If data is to be changed, the device must be discarded. • Blank PROMs are inexpensive • More fragile than PROMs • Known as one-time programmable (OTP) devices, • i.e., can only be programmed once. • EPROM – Erasable and programmable ROM – used to store small amounts of data that must be saved when power is removed • Characteristics: • Programmed in the same manner as PROM • Can be erased and reprogrammed repeatedly • To erase, expose to a strong source of ultraviolet (UV) light. This would reset the chip to its initial state • When erasing, the entire chip has to be erased, not in part. • More expensive than PROMs • Very essential part of testing and developing applications.

  8. Hybrid Memory • There are two hybrid devices, EEPROM and flash. They are used to store code. These devices combine the features of both RAM and ROM. • EEPROM – Electrically Erasable and Programmable ROM • Characteristics: • Similar to EPROMs internally • Can be erased electrically, and in part • Data can be erased and rewritten • Data remains on the device forever, unless electrically erased. • Flash Memory – USB (Universal Serial Bus) • Characteristics: • Is a type of EEPROM, everything is electrical instead of mechanical • It is used for easy and fast storage of information in devices such as digital cameras and home video game consoles • It stores large amounts of data • It is low cost, non-volatile, fast (to read)

  9. Definitions to know: • Bit – Short for Binary digIT and it is a single unit of information that can have a value of either ON or OFF. • Byte - A byte is a set of 8 bits that represent a single character. It is a unit of measuring the computer data storage capacity. • Kilobyte (Kb) – 1,024 bytes or characters • Megabyte (Mb) – 1,048,576 (about one million) bytes or characters • Gigabyte (Gb) – 1,073,741,824 (about one billion) bytes or 1024 Mb • Terabyte – one trillion bytes • Word – the largest amount of data which can be accessed at the same time. • Word size – the number of bits which can be transferred in a word

  10. Secondary Storage

  11. Secondary Storage • This is also known as auxiliary storage and is all data storage that is not stored in the computer’s primary storage or memory. • Characteristics: • Saves data and programs for later use • Each secondary storage device or medium requires its own drive. • Secondary storage is non-volatile • It is less expensive than primary storage • Uses devices and media • It is different from primary storage in that it is not directly accessibly by the CPU.

  12. Storage Devices • Storage devices records and retrieves data, instructions and information from storage media. • What are some examples of Storage Devices you can think of? • Hard disk drive • Floppy disk drive • Compact Disk drive • Zip drive

  13. Storage Media • Magnetic Media - Most common and cheapest way to store data • Optical Storage • Includes Floppy disks, Diskettes, Zip disks, Hard disks and Magnetic tape • These devices include CD-ROM, CD-RW drives and DVD drives. Some storage devices allow data to be saved as well as read.

  14. Home Work • SCSI • IDE • SATA • For each: • 1) What the acronym stands for? • 2) What it means?

  15. THE END