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C OMPUTER H ARDWARE(3)

C OMPUTER H ARDWARE(3). What is RAM?. RAM (random access memory) is a temporary holding area for data, application program instructions, and the operating system.

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C OMPUTER H ARDWARE(3)

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  1. COMPUTER HARDWARE(3)

  2. What is RAM? • RAM (random access memory) is a temporary holding area for data, application program instructions, and the operating system. • In a personal computer, RAM is usually several chips or small circuit boards that plug into the system board within the computer’s system unit.

  3. Why is RAM so important? • RAMisthe“waitingroom”forthecomputer’sprocessor. • It holds raw data waiting to be processed as well as the program instructions for processing that data. • It holds the results of processing until they can be stored more permanently on disk or tape. • It also holds operating system instructions, that loaded when starting a computer, to control it’s basic functions.

  4. How does RAM differ from hard-disk storage? • To differentiate between RAM and hard-disk storage: • RAM holds data in circuitry that’s directly connected to the system board, whereas hard-disk storage places data on magnetic media. • RAM is temporary storage; hard-disk storage is more permanent. • RAM usually has less storage capacity than hard-disk storage.

  5. How does RAM work? • InRAM,microscopicelectronicpartscalledcapacitors hold the bits that represent data. • Can visualize the capacitors as microscopic lights that can be turned on or off. • Turned on capacitor represents a “1” bit and turned offcapacitor represents a “0” bit. • Each bankof capacitors holds eight bits—one byte of data.

  6. How does RAM work? • A RAM address on each bankhelps the computer locate data, as needed, for processing. • Unlike disk storage, RAM is volatile: • Which means it requires electrical power to hold data. • If the computer is turned off or the power goes out, all data stored in RAM instantly and permanently disappears.

  7. How does RAM work?

  8. How much RAM does a computer need? • RAM capacity is expressed in megabytes or gigabytes. • Today’s personal computers typically feature 2–8 GB of RAM. • Amount of RAM a computer needs depends on the used software you. • RAM requirements are routinely specified on the outside of a software package.

  9. How much RAM does a computer need? • Today’s computer operating systems are quite smart at allocating RAM space to multiple programs. • Ifaprogramexceedsitsallocatedspace,theoperatingsystem uses an area of the hard disk, called virtual memory,to store parts of programs or data files until they are needed.

  10. Do all computers use same type of RAM? • RAM speed is often expressed in nanoseconds (ns) or megahertz (MHz millions of cycles per second). • Lower nanosecond ratings are better because it means the RAM circuitry can react faster to update the data it holds. • SDRAM (synchronous dynamic RAM) is fast and relatively inexpensive. • Improvements such as dual-channel technology and doubledatarate (DDR)have increased SDRAM speed.

  11. How is ROM different from RAM? • ROM (read-only memory) is a type of memory circuitry that holds the computer’s startup routine. • ROM is housed in a single integrated circuit which is plugged into the system board. • Whereas RAM is temporary and volatile, ROM is permanent and nonvolatile.

  12. How is ROM different from RAM? • ROM holds “hard-wired” instructions that are a permanent part of the circuitry and remain in place even when the computer power is turned off. • The instructions in ROM are permanent, and the only way to change them is to replace the ROM chip.

  13. If a computer has RAM, why does it need ROM too? • ROM contains a small set of instructions called the ROM BIOS (basic input/output system). • These instructions tell the computer how to access the hard disk, find the operating system, and loadit into RAM. • After loading the operating system, the computer can accept input, display output, run software, and access data.

  14. Where does a computer store its basic hardware settings? • A computer, to operate correctly, must have some information about storage, memory, and display configurations. • To store this information, the computer needs a type of memory that’s more permanent than RAM, but less permanent than ROM. • EEPROM(electrically erasable programmable read-only memory) is a non-volatile chip that requires no power to hold data. • When the configuration of a computer system is changed, as by adding RAM, the data in EEPROM must be updated. • Some operating systems recognize such changes and automatically perform the update.

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