Section 1 - Components of a computer Flashcards
What is the CPU also known as?
The CPU is also known as the processor
What components make up the CPU?
The CPU is made up of the control Unit, Buses, Arithmetic Logic Unit, and also dedicated registers
What does the Control Unit do?
The control unit controls and coordinates the activities of the CPU, as well doing the FDE cycle and storing the resulting data back in memory or registers
What is a Bus?
A bus is a set of wires which connect two or more components of a computer.
What are the 3 categories of buses?
Data Bus, Control Bus, Address Bus, together they are known as the System Bus
What does the Data Bus do?
The data bus is in charge of moving data around the computer
What does the Control Bus do?
The control bus sends control signals, which are used to synchronise the computer
What does the Address bus do?
The address bus transfers addresses around the computer
How many Control lines does the Control bus have?
6
What are these control lines?
Bus Request, Bus Grant, Memory Write, Memory Read, Interrupt Request, Clock
What is the Bus Request Control Line?
Indicates that a device is requesting the use of a data bus
What is the Bus Grant Control Line?
Indicates that the CPU has granted access to the data bus
What is the Memory Write Control Line
Causes data on the data bus to be written into the addressed location
What is the Memory Read Control Line?
Causes data from the addressed lcoation to be placed on the data bus
What is the Interrupt request control line?
Indicates that a device is requesting access to the CPU
What is the Clock Control Line
The Clock Control Line is used to synchronise operations.
What is the Arithmetic-Logic Unit
The Arithmetic Logic Unit is a special register which performs arithmetic and logical operations on data, before depositing it in the Accumulator.
What are the 5 main Registers inside of a CPU?
Accumulator, Program Counter, Current Instruction Register, Memory Address Register, Memory Data Register
What is the Accumulator
The Accumulator is where all calculations take place
What is the Program Counter
The Program Counter holds the address of the next instruction to be executed.
What is the Current Instruction Register?
The current instruction register holds the current instriction being executed, divided into Operand and Opcode
What is the memory address register?
The Memory Address Register holds the address of the memory location from which data is to be fetched from or to which data is to be written
What is the Memory Data Register?
The memory Data Register is used to temporarily store the data read from or written to memory.
What is the Fetch-Decode-Execute Cycle?
The Fetch-Decode-Execute Cycle is a sequence of operations involved in executing an instruction.
What happens in the Fetch Phase of the Fetch-Decode-Execute Cycle?
In the Fetch Phase of the Fetch-Decode-Execute Cycle, a total of three steps occur, these are:
1. The address of the next instruction is copied from the Program counter to the memory address register.
2. The instruction heald at that address is copied to the memory data register. Simultaneously, the content of the Program Counter is incremented so that it holds the address of the next instruction.
3. The contents of the Memory Data Register are copied to the Current Instruction Register.
What happens in the Decode Phase of the Fetch-Decode-Execute Cycle?
In the Decode Phase of the Fetch-Decode-Execute cycle, only one instruction is carried out, this instruction is:
4. The instruction held in the CIR is decoded, and split into opcode and operand.
What happens in the Execute Phase of the Fetch-Decode-Execute Cycle?
- The appropriate instruction/opcode is carried out on the operand
What is the Opcode?
The Opcode is used to determine the type of instruction and what hardware to use to execute it
What is the Operand?
The Operand can hold 3 different things, these are:
1. The address of the data to be used with the operation, which will be passed to the MAR
2. The actual data to be operated on, which will be passed to the MDR
3. The data to be operated on, which will be passed to the ALU/Accumulator
What are the 3 factors which affect the Processor’s performance?
- Clock Speed
- The number of cores
- The amount and type of cache memory
How does clock speed affect the processor’s performance?
Clock Speed affects the processor’s performance due to the fact that it works to synchronise the PC’s components, so if your computer has a slow clock speed, your computer would run slower since it takes longer to execute an instruction
How does having more Cores affect processor Performance?
having more Cores effects processor Performance
How does the amount of cache memory affect the processor’s performance?
The amount of cache memory affects the processor’s performance due to the fact that cache memory is very fast storage location inside the CPU, so having more of this means more data can be processed quickly
What are the 3 levels of cache?
Level 1, Level 2, Level 3
What is Level 1 Cache Memory?
Level 1 Cache memory is extremely fast but small (between 2-64KB)
What is Level 2 Cache Memory?
Level 2 Cache memory is fairly fast but medium sized (256KB - 2MB)
What is level 3 Cache Memory?
Level 3 Cache memory is slower than the other two but marge larger, being between 10MB and 64MB
what is Pipelining?
Pipelining is a technique used by processors to improve performance, it works by making it so that the computer can be fetched while the computer is executing an instruction, speeding up the Fetch-Decode-Execute cycle.
What are the two types of Pipelining?
Arithmetic Pipelining and Instruction Pipelining
What is Arithmetic Pipelining?
Arithmetic Pipelining represents the parts of an arithmetic operation that can be broken down and overlapped as they are performed.
How does Pipelining occur?
While the computer is executing an instruction, the Busses find the next piece of memory and hold this data close to the processor in a buffer zone, significantly cutting down on the time it takes to obtain data.
What is the Address Bus?
The Address Bus is a Bus that transfers the address of data that the processor needs, with the width of the address bus determining the maximum possible memory capacity of the system.
What is the Data Bus?
The data bus transmits the data held in a word of memory between processor components and memory. It splits the data into operand and opcode, with the operand containing the address of the data, while the opcode contains the data itself.
What does the von Neumann architecture specify?
The von Neumann architecture specifies the basic components of the computer and processor in which a shared memory and bus is used for both data and instructions.
What is the stored program concept?
The stored program can be defined as machine code instructions are fetched and executed serially by a processor that performs arithmetic and logical operations.
How is the Stored Program concept carried out?
The program being used must be a resident in main memory, if it is, the machine code instructions are fetched from memory one at a time, decoded and executed in the processor.
