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36 Cards in this Set
- Front
- Back
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what are 2 main parts of the cpu |
arithmetic logic unit ALU control unit |
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what does the ALU do |
numeric functions compares 2 numbers to see larger one carries out calculations |
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what does the control unit do |
responsible for retrieving data and instructions from correct location in memory
then executes it can call alu if needed |
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what is the clock speed measured in |
hertz Hz one operation per second MHz million GHz billion |
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what factors influence the speed of computer |
speed of other components e.g. waiting for hard disk size of cache number of cores |
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what is cache |
high speed memory stores frequently needed instructions or data |
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how is data represented by a computer |
binary 0 and 1 |
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why is binary used |
2 states which can mimic 0 and 1 magnet on hard disk can be aligned north or south circuit open close |
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why is binary good |
high tolerance cannot mistake 0 for 1 but 4.26 can be mistaken for 4.27 |
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what do logic gates do |
allow calculations and other operations by reading one or more inputs |
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what are the 3 types of logic gates |
and not or |
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when does and gate give one 1 |
when a and b are both 1 |
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when does not give 1 |
when a is 0 |
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when does or give 1 |
0 1 1 0 1 1 |
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what is ram |
random access memory volatile used when program is loaded from computers hard disk its data and instructions are loaded into ram |
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what does volatile mean |
when computer is turned off the content and data is lost |
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what is the pro of having more ram |
able to run more applications |
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ROM |
read only memory cannot be edited or deleted no updates required bootstrapping instructions |
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virtual memory |
used when ram not large enough part of hard disk is used as an extension of ram temporarily given memory addresses |
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cache memory |
stores copies of data and instruction from ram which are accessed regularly fast cache memory small kb mb not gb |
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flash memory |
uses electronic chips as storage non volatile portable solid state usb memory cards |
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what is OMR |
optical mark reader scan paper looking for marks in pre determined places lottery |
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what is OCR |
optical character reader recognise interpret characters on page |
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what does a servomechanism |
allows computers to control the physical activity of an external mechanism wheels on robot or sprinklers |
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eye typer |
determines where the eye is focused on screen and moves cursor there |
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braille keyboard |
number and letter is represented by a pattern of dots raised |
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puff suck switch |
blowing intro sucking on a tube input depends on software ideal for yes no questions |
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text to speech |
reads text out |
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output devices specific needs |
braile printer text to speech screen magnifiers |
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is main memory volatile |
yes |
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is secondary storage volatile |
no |
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what is the most common secondary storage |
internal hardisk |
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what do magnetic storage include |
internal hard disks as well as floppy disks no longer widely used disks round separated into tracks and sectors |
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what access data in hard disk |
read write head disk spins at 7200 revolutions per minute |
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optical storage |
cd dvds blu ray written and read from using lasers spin to allow laser to read from correct location surface will have holes dips burned not burned to represent 0 1 |
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solid state |
electronics circuits no moving parts sturdier and quite than magnetic / optical devices |
