Topic test The CPU State the purpose of the CPU

Topic test
The CPU
State the purpose of the CPU. 1
The CPU controls and coordinates all the other components of the computer.

List the two operations carried out by the ALU.2
The ALU carries out arithmetic (maths) and logic (true/false) operations.
(b.) Describe the role of the control unit in the operation of the central processing unit. (2)
 The control unit decodes the instructions sent to it from the RAM and controls the
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 buses. The buses are used to transport data and the addresses of the data in the
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registers.

 
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Explain the steps involved in the Fetch-Decode-Execute cycle. 4
At the start of the fetch-decode-execute cycle, the MAR holds the address of the first instruction in the RAM. The data bus fetches the data stored at this address and stores it in the MDR. The control unit decodes the instructions saved in the MDR and sends them to the ALU to be carried out. The result is saved into an empty memory slot.

Ann wants to purchase a new computer and is looking at two models. The specification of the CPU in each computer is shown in Fig. 1. (1)

Explain one reason why the cache size affects the performance of the CPU.

The cache is low capacity high performance memory. The more cache that exists, the more data can be stored in it, increasing the CPUs’ performance. 
2
 
With reference to memory, describe the characteristics of von Neumann architecture 1
The Von Neumann architecture used volatile memory to hold the current running processes.
6. Gareth has a satellite navigation system (Sat Nav) in his car that uses RAM and ROM.Fig. 2 lists some characteristics of computer memory. Tick (?) one box in each row to show whether each of the statements is true for the RAM or ROM in Gareth’s Sat Nav.

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(4 marks)
Describe the purpose of the Memory Address Register (MAR) and the Memory Data Register (MDR)2
The MAR stores the memory location of the currently used data.

The MDR stores the data that was found at the address from the MAR
Explain how cache memory, clock speed and number of cores can affect the performance of a CPU.

(a)clock speed 2
Clock speed is the number of processes that can take place per second. The more processes that can take place, the faster the computer can run.

(b)Number of cores 2
Each core can run one process at a time. The more that there is, the more processes can be run simultaneously.

(a)Describe what is meant by an embedded system.2
An embedded system is a device that only completes one job. There is usually a lot of embedded systems in a device.
(b)Give two examples of devices which use embedded systems2
Washing machines and cars use embedded systems.

(c)Satnav devices make use of embedded systems. State one way how a SatNav device would make use of the embedded system.1
A satnav device would use an embedded system to get the GPS location.

Explain the use of cache memory and the role it plays in improving processing speeds.3
Cache memory improves processing speeds as it is high speed storage that holds often-used processes.

Name two devices other than a desktop computer which might use flash memory as their form of memory storage. In each case justify your answer. Your answers should be different in each case.4
Mobile phones and tablets use flash memory.

4) State the role of the following registers in the Fetch-decode-execute cycle.

a) The program counter (2)
The program counter holds the step in the program that the CPU is currently at.

b) The memory data register (MDR)
The memory data register holds the data at a specific location.Total Marks, 35