Unit 1 : Components of a computer and their uses Flashcards
1
Q
What is the processor
A
- The processor is the brain of the computer, it executes instructions which allows programs to run
2
Q
What is the Arithmetic and logic unit
A
The ALU carries out all arithmetic and logical operations
3
Q
What is the control unit
A
- The control unit is a processor which directs the operations of the CPU, its jobs are :
- Controlling and coordinating the activities of the CPU
- Managing the flow of data between the CPU and other devices
- Accepting the next instruction
- Decoding instructions
- Storing the resulting data back in memory
4
Q
What is a register
A
- Registers are small memory cells that operate at very high speed. They are used to temporarily store data and all arithmetic, logical and shift operations occur in these registers
5
Q
What are the different registers
A
- Program Counter (PC)
- Accumulator (ACC)
- Memory Address Register (MAR)
- Memory Data Register (MDR)
- Current Instruction Register (CIR)
6
Q
What does the program counter do (PC)
A
- Holds the address of the next instruction to be executed
7
Q
What does the Accumulator do (ACC)
A
- Stores the results from calculations
8
Q
What does the Memory Address Register do (MAR)
A
- Holds the address of a location that is to be read from or written to
9
Q
What does the Memory Data Register do (MDR)
A
- Temporarily stores data that has been read or data that needs to be written.
10
Q
What does the Current Instruction Register do (CIR)
A
- Holds the current instruction being executed, divided up into operand and opcode.
11
Q
What are buses
A
- Buses are a set of parallel wires which connect two or more components inside the CPU.
- There are three buses in the CPU: data bus, control bus, and address bus.
- These buses collectively are called the system bus
12
Q
What does the data bus do
A
- This is a bi-directional bus (meaning bits can be carried in both directions) used for transporting data and instructions between components
13
Q
What does the address bus do
A
- This is the bus used to transmit the memory addresses specifying where data is to be sent to or retrieved from. The width of the address bus is proportional to the number of addressable memory locations
14
Q
What is the control bus
A
- This is a bi-directional bus used to transmit control signals between internal and external components.
15
Q
What are the control buses signals
A
- Bus request: shows that a device is requesting the use of the data bus
- Bus grant: shows that the CPU has granted access to the data bus
- Memory write: data is written into the addressed location using this bus
- Memory read: data is read from a specific location to be placed onto the data bus,
- Interrupt request: shows that a device is requesting access to the CPU
- Clock: used to synchronies operations
16
Q
How does assembly language work
A
- Assembly code uses mnemonics to represent instructions, for example ADD represents addition. This is a simplified way of representing machine code.
- The instruction is divided into operand and opcode in the Current Instruction Register.
17
Q
What does the opcode do
A
- The opcode specifies the type of instruction to be executed.
18
Q
What does the operand do
A
- The operand contains the data or the address of the data upon which the operation is to be performed
19
Q
What is pipelining
A
- The process of completing the fetch, decode, and execute cycles of three separate instructions simultaneously
- Data is held in a buffer in close proximity to the CPU until it’s required
- Pipelining is aimed to reduce the amount of the CPU which is kept idle.
