Hardware Revision

fasiteko's version from 2016-04-02 16:35

Section 1

Question Answer
What is the purpose of the CPU?The CPU (the central processing unit) which contains the processor, main memory and cache memory, is responsible for fetching instructions from main memory, decoding and executing the instructions fetched, performing calculations and managing the movement of instructions and data to and from peripheral devices
What is the fetch execute cycle?The process by which a program is run: instructions are stored in main memory, fetched by the processor one at a time, decoded and executed.
What is the function of the arithmetic logic unit (ALU)? To carry out all of the arithmetic and logical operations
What is the function of the control unit?The part of the CPU that uses electrical signals to control the flow of data within the CPU
Define and explain how clock speed affects the performance of the CPU Measured in hertz or cycles per second, the clock speed represents how many instructions per second the processor can execute. The higher the clock speed, the faster the CPU can operate.
Define cache memory and explain how greater cache size improves CPU performance High speed memory in the CPU that is used to store a copy of frequently used instructions and data. Since it has a faster access speed than main memory and the processor will have to access main memory less frequently, CPU performance is improved.
What is a multi-core processor and how does it affect performance?A CPU that contains multiple processor components(cores) that can operate independently to process more than one task at a time. Therefore, each core is able to process different programs that are operating in parallel, meaning that more data is processed simultaneously.
What is a disadvantage of a multi-core processor?More complicated operating systems are required to manage them
Define system buses and explain their purposeThe circuits/wiring that connects the processor and main memory together. The program instructions and data move between the main memory and the processor via these connections

Section 2

Question Answer
Define Volatile memoryDescribes memory that loses its contents when the power is turned off. Eg: main memeory
Define Non Volatile memoryDescribes memory that does not lose its contents when the power is turned off
What is RAM/main memory and its purpose?Random Access Memory, also known as Immediate Access Store and Primary memory, this is memory in the CPU that is used to temporarily store programs while they are running and data used by these programs. The processor fetched instructions from main memory, which is made up of many addressable locations. This type of memory is read-write and volatile.
Define ROM and its purposeRead Only Memory: memory that is hard-coded at the time of manufacture that is responsible for storing the start-up programs (such as the Bootstrap Loader). This type of memory is read only and non-volatile.
Define Bootstrap LoaderThis is the first program that is loaded into main memory from ROM when a computer is switched on. This will load the operating system from secondary storage.
Explain the difference between RAM and ROMRAM is read-write and volatile whilst ROM is read only and non volatile. Whilst RAM can be accessed and changed by the computer at any time, ROM is programmed during computer manufacture. Whilst RAM stores programs and data currently bing used by the computer, ROM stores the data and instructions required to start up the computer. RAM contains the operating system whilst ROM contains the boot program. RAM is relatively large in size (4GB or more in a typical computer) whilst ROM is much smaller (only 1 or 2MB required for the boot program)
Explain the need for RAM in a computer systemReading from and writing directly to a hard disk is very slow compared to the speed of the processor.  Therefore, main memory is needed in order to improve access speed and prevent the computer from being very slow
Describe and explain the purpose of virtual memoryPart of the hard disc that is configured to behave as an extension to main memory. It is used when the computer does not have enough RAM to hold all the programs and data required. Data is passed between RAM and virtual memory - access to virtual memory is much slower than than to RAM
How does the amount of RAM available affect the performance of the computer? More main memory means that more instructions can be held within main memory - this means it reduces the use of slower virtual memory, thereby improving the performance of the computer.
Define Secondary Memory Long term, non volatile storage media such as hard discs.
How have changes in memory capacity lead to innovative computer designs?More data can now be stored without devices becoming larger in size - this is due to development of SD cards which come with a high capacity. Also, capacity of primary memory has improved, so more applications can be run at the same time.
How have changes in memory speed lead to innovative computer designs?Although Flash memory is still slower than RAM, it is significantly faster than a magnetic hard disc. This has resulted in bulky hard discs being replaced by smaller, lighter, faster and more reliable flash memory.
How have changes in memory proce lead to innovative computer designs?Flash memory is cheaper and easier to produce so devices using flash memory become cheaper as well. Lower cost memory has improved the capacity of gadgets like MP3 players, hand‐held game consoles and phones. Also, cost of RAM has dropped, meaning that cheaper PCs come with a greater capacity than in the past.

Section 3

Question Answer
Describe Magnetic Media Used in hard discs/floppy discs, magnetic media have a high capacity and come at a low cost. Magnetic disc are read by a moving head inside the disc drive and magnetic tapes are read by moving the tape past a read-write head. However, these moving parts make it slow to read or write to and also more vulnerable to damage.
Describe Optical DsicsExamples of optical disc include CDs and DVDs. Data is written to and read from these diskc using a laser. Optical discs have a good capacity(CDs - 700MB DVDs - 4.7GB), come at low cost and are lightweight and easily portable making them ideal for transferring files or distributing software
Describe Flash/Solid State Memory Contains no moving parts, means that it can be produced relatively cheaply + less vulnerable to damage. Consumes little power. Good capacity but less than that of hard disc. Though cannot replace RAM in main memory because access speed is too low, it is ideal for use in hard disc in hand held devices.

Section 4