1.1.1 - Characteristics of processors I/O & storage

?
  • Created by: A09393
  • Created on: 10-06-19 09:43
Describe the purpose of the CPU
The Central Processing Unit is responsible for carrying out all the instructions (billions per second using transistors).
1 of 29
Describe the purpose of the ALU (include examples)
The Arithmetic Logic Unit performs calculations, makes logical decisions. It is the gateway between the CPU & the rest of the computer. The results of its calculations are stored in the accumulator.
2 of 29
Describe the purpose of the CU (include examples)
The Control Unit decides which instruction to fetch, decode & execute. It sends out control signals to co-ordinate how the processor works. It controls the movement of data between different parts of the CPU & between the CPU & memory.
3 of 29
Describe the purpose of the cache
It is a small amount of memory which is a part of the CPU. It is physically closer to the CPU than RAM and therefore is faster to access. It is used to temporarily hold instructions and data that the CPU is likely to reuse in the near future.
4 of 29
Describe Von Neumann architecture
The processor needs two clock cycles to execute an instruction. It uses a simpler CU design which is cheaper and faster. Data can be transferred and instructions can be performed at the same time. It is used in PCs and laptops.
5 of 29
Describe how instructions and data are sent (Von Neumann)
The instructions and data are sent along the same bus therefore instructions cannot be fetched at the same time as data is being sent which results in a "bottle-neck".
6 of 29
Describe Harvard architecture
The processor needs one clock cycle to complete an instruction. The CU needs to co-ordinate the two buses which is more complex & expensive. Data can be transferred and instructions can be performed at the same time. It is used in micro-controllers.
7 of 29
Describe how instructions and data are sent (Harvard)
The data and instructions are sent along two different buses and are stored in separate memory units which overcomes the Von Neumann "bottle-neck".
8 of 29
Define the term register
It is an area of the processor that stores specific data. They are temporary memory that are very fast to access. They are used in the FDE cycle when fast access is essential.
9 of 29
Name and describe what the MAR stores
The Memory Address Register holds the address of the instruction or data that is to be fetched or written to memory.
10 of 29
Where can the address come from? (MAR)
The address can come from the PC when the processor needs a new instruction or the CIR when it needs the address of an operand during decoding process or needs to write something to memory.
11 of 29
Name and describe what the MDR stores
The Memory Data Register holds data/instruction that has just been read from memory. It holds data that is about to be written to memory. Instructions are then sent to the CIR.
12 of 29
Name and describe what the PC stores
The Program Counter stores the address of the next instruction to be executed. It is needed so the processor always knows where the next instruction is.
13 of 29
How can the content be changed? (PC)
It can be incremented naturally as part of the FDE cycle or it can be changed by a JUMP instruction.
14 of 29
Describe what the accumulator stores
It is temporary storage within the ALU. It holds data being processed during calculations and the final results of processing. It deals with the inputs & outputs in the processor.
15 of 29
Name and describe what the CIR stores
The Current Instruction Register holds the current instruction that is to be decoded. The CU splits up the instruction in two parts (opcode & operand).
16 of 29
What is done with the opcode & operand? (CIR)
The opcode is looked up in the opcode table to understand what to do. The address of the operand will be sent to the MAR so the opcode can be fetched. The CIR holds the instruction as it is being executed.
17 of 29
Describe what a bus is
It is a circuit (path) down which instructions or data can pass. It allows the CPU to communicate with all the other hardware.
18 of 29
Describe the purpose of the control bus
It carries control commands from the CU to different parts of the processor.
19 of 29
Describe the purpose of the address bus
It carries the address of the location to which the data in the data bus should be delivered.
20 of 29
Describe the purpose of the data bus
It carries data from one register to another.
21 of 29
Describe the fetch part of the FDE cycle (include registers & buses)
The PC holds the address of the next instruction to be carried out. When the next instruction is needed, it's address is copied from the PC and placed in the MAR. The PC is incremented by the program loader so it points to the next instruction.
22 of 29
Describe the fetch part of the FDE cycle (include registers & buses) - pt2
The address in the MAR is found in memory and the contents are placed in the MDR. The contents of the MDR are then copied to the CIR ready for decoding.
23 of 29
Describe the decode part of the FDE cycle (include registers & buses)
The instruction in the CIR is split into its individual parts (operation code & the address of the data involved). The address is placed in the MAR and the data in the address is sent to the MDR. The CU decodes the opcode so the CPU knows what to do.
24 of 29
Describe the execute part of the FDE cycle
The instruction is executed. It either performs a logical/arithmetic based instruction or execute a jump instruction.
25 of 29
Define the term clock speed
It is the number of instructions a single processor core can carry out per second (in hertz).
26 of 29
Describe how large cache reduces the need to access slower RAM
The more cache there is, the more data can be stored closer to the CPU (speeding up processing) reducing the need to access RAM.
27 of 29
Describe how the number of cores affects the performance
A CPU can contain one or more processing units (core). CPUs with multiple cores have more power to run multiple programs at the same time. Different cores can run different applications or they can work on the same problem.
28 of 29
Describe what pipelining is and how it affects efficiency
A processor works by repeatedly fetching It means that as an instruction is being executed, another one can be decoded and a third can be fetched.
29 of 29

Other cards in this set

Card 2

Front

Describe the purpose of the ALU (include examples)

Back

The Arithmetic Logic Unit performs calculations, makes logical decisions. It is the gateway between the CPU & the rest of the computer. The results of its calculations are stored in the accumulator.

Card 3

Front

Describe the purpose of the CU (include examples)

Back

Preview of the front of card 3

Card 4

Front

Describe the purpose of the cache

Back

Preview of the front of card 4

Card 5

Front

Describe Von Neumann architecture

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Computing resources:

See all Computing resources »See all Structure and function of the processor resources »