sytem unit part ii

7/25/2019 Sytem Unit Part II

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MEMORY

Memory Memory consist of electronic

components that store instructionswaiting to be executed by theprocessor, data needed by thoseinstructions, and the results ofprocessed data ( information).

Memory usually consist of one ormore chips on the motherboard.


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MEMORY

Memorytores ! basic categories of

items"

#. $he operations%. &pplication programs

!. $he data being processedby the application programsand resulting information.


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MEMORY

Memory si'es

ts the number of bytes the chip orde*ices has a*ailable for storage.

Term Abb.Approximate no. of

byteExact no. of

byte

Kilobyte KB or K 1000 1,024

Megabyte MB 1Million 1,048,5!

"igabyte "B 1Billion 1,0#,41, 824

Terabyte TB 1 Trillion 1,0$$,511,!2,!


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$ype of Memory$ype of Memory

$he system unit contains two types of memory"

#.#. +olatile memory+olatile memory

-oses its contents .

$emporary memory. Example, R&M.

%.%. on*olatile memoryon*olatile memory

doesn/t lose its content when power is

remo*ed from the computer. 0ermanent memory.

Example, ROM, 1lash memory, and2MO.


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R&M (Main Memory)

R&M ( Random &ccess Memory ), &lso 2alledmain memory.

consists of memory chips that can be readfrom and written to by the processor andother de*ices.

$he content may changed.

a*ing is a process of copying items from R&Mto a storage de*ice such as a hard dis3.


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R&MR&M ( Random &ccess Memory )

R&M chips usually reside on a memorymodule, which is a small circuit board.

Memory slots on the motherboard holdmemory modules.


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ROM

ROM ( Read Only Memory)

$he data on most ROM chips cannot bemodi4ed.

Manufacture of ROM chips often recorddata, instructions, or information on thechip when they manufacture the chip.

2omputers almost always contain a smallamount of readonly memory that holdsinstructions for starting up the computer.


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$Y0E of ROM

$ypes of ROM"

0ROM (programmable readonly memory)" & 0ROM isa memory chip on which you can store a program. 5utonce the 0ROM has been used, you cannot wipe it

clean and use it to store something else. -i3e ROMs,0ROMs are non*olatile.

E0ROM (erasable programmable readonly memory)"&n E0ROM is a special type of 0ROM that can be

erased by exposing it to ultra*iolet light.

EE0ROM (electrically erasable programmable readonly memory)" &n EE0ROM is a special type of 0ROMthat can be erased by exposing it to an electrical

charge.
http://webopedia.com/TERM/M/EPROM.htmlhttp://webopedia.com/TERM/M/EEPROM.htmlhttp://webopedia.com/TERM/M/EEPROM.htmlhttp://webopedia.com/TERM/M/EPROM.html


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Memory &ccess $ime

Memory &ccess $ime

t is the amount of time ta3es the processorto read data, instructions, information frommemory.

ts a6ects how fast the computer processdata.

&ccess time on memory can be more than%77,777 times faster than accessing data ona hard dis3 because the mechanical motionof it.


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Memory &ccess $ime 8nits

Memory &ccess $ime

Term Abb. %pee&

Milli'econ& m' (ne)t*o+'an&t* of a 'econ&

Micro'econ& ' (ne)milliont* of a 'econ&

-ano'econ& n' (ne)billion of a 'econ&

ico'econ& p' (ne)trilliont* of a 'econ&


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Expansion lot and &dapter 2ards


Expansion slot is a soc3et on the motherboardthat can hold an adapter card

&dapter cardsometimes called an expansioncard

is a circuit board that enhances functions of acomponent of the system unit and9or pro*ides

connections to peripherals. 0eripheralis a de*ice that connects to a system

unit and is controlled by the processor. Ex"3eyboard, printer.


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$ypes of adapter cardsAdapterCard

Purpose

Graphicsaccelerator

Increases the speed at whichgraphics are displayed

Modem Connect other computers throughtelephone or cable TV line

Network Connects other computers andperipherals

Sound Connects speakers or microphone

Video Connects a monitor


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0orts and 2onnectors

0ort is the point at which a peripheralattaches to or communicates with asystem unit so the peripheral can send

data to or recei*e information from thecomputer.

the term :ac3 sometimes is used toidentify audio and *ideo ports.

0ort ha*e a di6erent types of connectors,& connectors :oins a cable to a peripheral.


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erial 0orts is a type of interface thatconnects a de*ice to the system unit bytransmitting data one bit at a time.


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0arallel 0orts is an interface thatconnects a de*ice by transferringmore than one bit at a time.

$he printers using a parallel port.


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Ports and Connectors

85 0orts, hort for uni*ersal serial busport.

2an connect up to #%; di6erentperipherals together with a singleconnector.

85 hub is a de*ice that plugs in a 85port on the system < contains multiple85 ports.


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1ire=ire 0orts 0re*iously called an EEE #!>?port.

t is similar to a 85 port in that it can

connect multiple type of de*ice that re@uirefaster data transmission speeds to a singleconnector, such as digital *ideo camera, colorprinters, scanners, .. etc.

&llow you to connect up to A! de*icestogether.

You can use a 1ire=ire hub to attach multiplede*ices to a single 1ire=ire port.

85 and 1ire=ire are replacing all other types

of port.


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Ports and Connectors

pecial0urpose 0orts

$hese ports are not included in

typical computers. MB 0ort

2 0ort

rB& 0ort 5luetooth 0ort


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MB 0ort, short for musical instrumentdigital interface.

erial port

2onnect the system unit to 3eyboard.

2 0ort

& special highspeed parallel port.

&llow you to attach 2 peripheralssuch as dis3 dri*er and printers.


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58E

a set of electronic signal pathways that allowsinformation and signals to tra*el betweencomponents inside or outside of a

computer.

5uses transfer bits

from input de*ices to memory.

from the processor to memory, and frommemory to the processor.

from memory to output de*ices.


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0ower upply

0ower upply

s a component of the system unit thatsupply computer with power.

T! !N"


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T! !N"

#y$ Mam

sytem unit part ii

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