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20 Cards in this Set
- Front
- Back
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State the purpose of the CPU
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The purpose of the CPU is to process data. It is where all the searching, sorting, calculating and decision making takes place.
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Briefly explain what happens during the ‘Fetch’ part of the Fetch-Decode-Execute Cycle.
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The CPU fetches data and instructions from main memory using a hardware path called an address bus
It stores them in internal, temporary memory areas called registers |
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Briefly explain what happens during the ‘Decode’ part of the Fetch-Decode-Execute Cycle.
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The CPU decodes the instruction that it has just fetched in the first part of the cycle using the ‘instruction set’ (specific to that brand of CPU).
It prepares various areas within the chip in readiness for the next step. |
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Briefly explain what happens during the ‘Execute’ part of the Fetch-Decode-Execute Cycle.
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This is the part of the cycle where the data processing takes place. The instruction is carried out upon the data (executed). The result of this processing is stored in yet another register.
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What happens once the complete cycle is complete?
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The CPU sets itself up to begin another cycle.
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What are the three main parts to the CPU?
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1. The Control Unit
2. The Immediate Access Store 3. The Arithmetic and Logic Unit. |
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Explain the purpose of the Control Unit.
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The Control unit has three main jobs:
• It controls and monitors the hardware attached to the system e.g. it will check that a document you sent to be printed goes to the correct printer • It controls the input and output of data so that the signals go to the right place at the right time • It controls the flow of data within the CPU. |
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Explain the purpose of the Immediate Access Store
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• The IAS holds the data and programs needed at that instant by the Control Unit.
• The CPU reads data and programs from the backing storage and stores them temporarily in the IAS’s memory. |
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Explain the purpose of the Arithmetic and Logic Unit
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• The ALU is where the computer processes the data by manipulating or acting upon it.
• In the Arithmetic part, calculations are performed on the data. • In the Logic part comparisons on the data are performed e.g. if one value is greater or less than another. |
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Briefly explain why the CPU cannot access data directly from the hard disk
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The CPU can process data very quickly. The hard disk cannot supply data at the speed the CPU is able to work at. If data was accessed directly from the hard disk, the computer would run very slowly.
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Briefly explain the purpose of the clock in the CPU
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Inside the CPU is a quartz clock which ticks very fast.
Every time the clock ticks, the CPU can process one piece of data or instruction. |
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What would be an average speed for a clock in a home PC.
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3 Gigahertz (3 GHz)
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How many instructions per second would this allow the CPU to process?
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Three thousand million instructions per second.
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Explain why your computer performance would be improved if you purchased a CPU with a faster clock speed.
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The faster the clock speed, the more instructions that can be processed per second. This improves the performance of the computer as more tasks and data can be processed in a shorter space of time.
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Explain what is meant by the term, ‘overclocking’
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Some people want to get the best performance possible out of their computer, perhaps to play computer games. To do this, they adjust the clock speed to run faster than the CPU was designed for, this is overclocking.
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What is the main problem caused by overclocking and how can it be overcome?
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When the CPU runs faster than it is designed for, it gets very hot and it could start to wear out or not function correctly. To overcome this, extra cooling fans are required.
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Explain what is meant by a dual-core and a quad-core device.
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A dual core device is where there are two CPUs to share the processing load.
A quad core device is where there are four CPUs to share the processing load. |
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Explain why a dual-core device does not double the processing power.
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Although there is double the processing power than a single CPU, many applications have not been written to take advantage of extra processors. This means that a lot of the processing power of the second processor lies idle.
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Explain the purpose of the cache
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The CPU can work at very fast speeds. In order to do this, it needs data supplied to it very quickly. Although RAM is much faster than the hard disk, it is not fast enough to supply the data required by the CPU.
The cache is a special kind of computer memory that can be accessed much faster than RAM. The CPU looks in the cache for the data if it needs. If it is in the cache, it processes the data, if not, it has to fetch the data from RAM. |
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Is cache memory volatile or non-volatile?
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Volatile
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