3.1.8 Computer Structure Flashcards
what is volatile memory?
computer memory the requires a power supply in order to maintain stored data
the moment that the power is turned off the information is lost.
give an example of volatile memory
RAM (random access memory)
what is non-volatile memory?
computer memory that retains its information whether the power being supplied to it is turned off or on
give an example of non-volatile memory
read only memory (ROM) and flash memory, as well as most types of magnetic hard disks and optical disks.
what is ROM?
(read only memory)
non-volatile, the data is pre-installed and cannot be changed
what is RAM?
(random access memory) - volatile
When a program is opened, it get loaded from the hard drive into the RAM, because reading data from RAM is much quicker, making the program’s use quicker.
Why is it important for computers to have a sufficient amount of RAM?
A large amount of RAM enables more instructions to be loaded from the secondary storage into RAM, so they can be executed by the processor.
what is Cache Memory?
- memory closest to the CPU.
- stores recently used data that can be accessed quickly at a later time
- larger amount of data means more cache-hits likely (CPU finds stored data), so processes will operate faster
- very expensive so is limited in capacity
Explain why having cache memory can improve the performance of the central processing unit (CPU)
Frequently used data/instructions are stored in the cache
Meaning they don’t have to be fetched from main memory.
Therefore data/instructions stored in the cache memory can be accessed faster
what is virtual memory?
- memory management procedure used when RAM is insufficient. stored temporarily on the hard drive (extends RAM capacity)
- much slower than RAM as it takes up more processing power to move the data around.
what is a CPU?
Central Processing unit
processes data and undertakes instructions given by applications and inputs
the CPU undertakes instructions it receives from programs in what is called …
a cycle, measured in Hertz (Hz)
how is the speed of a CPU measured?
by how many cycles it can perform in a second
(clock speed)
what instructions does a CPU’s control unit perform?
Fetch, Decode and Execute instructions then Store results.
factors improving performance of a CPU {5}
- the cache size
- the type of cache memory
- the number of cores/processors
- the processing clock speed
- the bus width
what is the clock speed and how does it affect the CPU’s performance?
- Speed at which the a microprocessor (meaning contained on one chip) executes instructions
- A higher clock speed means a process will be completed quicker
- However increased clock speed means increased heat produced and more power consumed
how does the number of cores affect the CPU’s performance?
[multiple CPU cores on a single chip are called multi-core processors]
multiple cores can run multiple instructions at any given time, so they’re effective when the user is multitasking.
However, software must specifically written to cater for multiple cores
what is a graphics card?
contain a processor like the CPU and can be used to process the graphic portion of the processing load.
Developments in hardware have made smart phones possible to include: {4}
- More power efficient processors
- Smaller form memory
- Solid state memory
- Affordable touch screens
what is the purpose of a Motherboard?
links the CPU to the memory and other hardware.
what is (high) reliability?
when a computer system can be depended on to work almost all of the time
what is robustness?
the ability of a computer system to cope with execution errors
why is high reliability and robustness important?
mean that the computer system can be depended on at all times without any chance of failure
what would happen if a system wasn’t reliable or robust?
the user may not be able to use the program when required, which, depending on the situation, could have severe consequences.
how can computer systems be made reliable?
duplication of the whole system so that if there is an error, there is always a backup to replace it in case it stops working.
what is a computer system?
a combination of hardware and software
what is secondary storage?
non-volatile memory that is used to store large amount of data permanently.
examples of secondary storage {3}
Flash memory > Solid State Memory > USB Memory sticks Optical media > CDs > DVDs Magnetic media > Hard disk drives > Floppy disks
how does Optical Media work? {6 steps}
- Digital optical discs store binary data as pits and lands on the disc’s surface
- Bits are encoded as transitions between lands and pits.
- An infrared laser is beamed through the CD’s material to read the data
- The light that bounces off the mirror-like reflective backing is then measured.
- An opto-electric sensor can read the stamped pattern by detecting fluctuations in the reflected beam as the laser scans the groove. - - These measurements can then be translated back into binary
how does Magnetic Media work? {for magnetic tape and discs}
- Data is stored as tiny magnetised dots.
- These dots are created, read and erased using magnetic fields created by tiny electromagnets.
In the case of magnetic tape the dots are arranged along the length of a long plastic strip which has been coated with a magnetisable layer
In the case of magnetic discs (e.g. floppy disc or hard-drive), the dots are arranged in circles on the surface of as disc that has a magnetisable coating.
how does Solid State work? {4 steps}
- no moving parts (solid)
- A SSD (solid state drive) uses microscopic electronic switches to store data.
- Millions of transistors are either on or off and remain so as long as electricity is applied to the system.
- SSDs use switches called floating gate transistors. These create a special cage that traps the electron flow within it.
- This effect continues whether there is electricity in the system or not, and so storage remains when the power is removed.
Advantages of Solid state media over Magnetic Media {4}
- Speed of read access is higher in solid state drives because data can often be read more quickly
- Solid state media can be more compact than magnetic media which enables better portability
- Magnetic media has mechanical parts so it’s unsuitable for mobile use because the mechanical parts are less robust during movement.
- Solid state battery will last longer as it uses less power
what does VGA mean?
video graphics array
why is bus speed in a motherboard important?
controls how much data the motherboard bus can handle at any one time. more data = faster system
why are computer system are essential in modern society?
- They allow people to contact and work with those all around the world
- They allow people to access their data securely from anywhere
- They improve quality of life, e.g. those without limbs can have then replaced with bionic
- They help save lives, e.g. emergency response teams can coordinate rescues quicker
