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15 Cards in this Set
- Front
- Back
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Register: The PC |
The Program Counter: Keeps track of where in the computer's memory the next instruction can be found, so it can then be placed into the CIR. |
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Register: MAR |
The Memory Address Register: Used to hold the address in memory that contains the next instruction, or piece of data to be used.
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Register: MDR |
The Memory Data Register: Used to temporarily store data read from or written to memory. It acts like a buffer and holds anything that is copied from memory ready for the processor to use it. |
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Register: CIR |
The Central Instruction Register: Holds the Operand and the Operator of the current Instruction. |
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Register: A |
The Accumulator: Is used for performing arithmetic functions. |
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How are Registers Used? |
1. The instruction is executed,
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What Is a Bus? |
A Bus is a set of parallel wires connecting two or more components of a computer system. |
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The Address Bus |
When the CPU wishes to access a particular memory location it sends this address to memory on the address bus. The width of the address bus determines the maximum possible memory capacity of the system. |
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The Data Bus |
The data bus provides a bi-directional path for moving data and instructions between system components.The width of the data bus is a key factor in determining overall system performance. This is bi-directional. |
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The Control Bus |
The control bus is bi-directional so signals can be carried in both directions. The control bus is used to ensure that the use of the address and data buses does not lead to conflict.
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Physical (Wired) Connectivity |
Physical 1. Fibre optic cable |
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Wireless Connectivity |
Wireless
WiFi Bluetooth Infrared Satellite |
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RAM |
RAM is used for storing data that is currently being processed. It is Volatile so it is wiped if a computer is switched off. |
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ROM |
ROM is non-volatile with its contents permanently etched on to a computer chip. It is primarily used to hold the Boot-Strap loader. In embed circuits (washing machines and the like) all the instructions may be stored in ROM. |
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How Data is Transferred from Secondary to Primary Memory |
Step 1: The processor needs to work on some data that is stored in secondary memory. Step 2: The processor can only work with data in Primary memory so the data needs to be transferred from Secondary to Primary memory. Step 3: The CPU tells Secondary Memory it wants the data. Step 4: The data in SM is slowly written in to a fast piece of memory called a buffer. Whilst this is happening the processor is working on other tasks. Step 5: When the buffer is full an Interrupt is sent to the CPU telling it the data is ready and the data is read from the buffer to PM where it is manipulated by the processor.
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