Hardware Elements

Question 1

The order sequence for Interupts

Answer 1

• The sequence of events is :

1. Interrupt is raised
2. Current CPU instruction is completed
3. Contents of internal registers are stored in (pushed onto) the stack
4. The memory address of the ISR is found and transfer controlled
5. ISR is run
6. Internal register contents are restored (popped) from the stack
7. Original process continues from where it was stopped

Question 2

NON-MASKABLE INTERRUPT (NMI)

Answer 2

• Isthe highest-priority interrupt capable of interrupting all software and non-vital hardware devices.

• Dedicated line on the control bus which interrupts the processor and cannot be ignored

• The NMI is not commonly used and usually only used to verify if a serious error or unrecoverable error has occurred or stop all operations because of a failure.

• For example, when you press Ctrl+Alt+Del when the computer freezes or stops responding a NMI is sent to the CPU.
100%

Question 3

What is a CPU?

Answer 3

•part of the computer that executes instructions o constructed from millions of transistors

•tiny pieces of silicon that will not conduct electricity if a low voltage is applied to them, but can conduct at higher voltage

• known as semi-conductors.

Question 4

What are the three components of. a CPU?

Answer 4

A CPU has three main components:

• the Arithmetic and Logical Unit (ALU)
• the Control Unit
• Registers
• Modern CPUs are integrated circuits (ICs) which combine these three components on a single silicon chip.

Question 5

What is ALU on CPU?

Answer 5

• carries out the mathematical functions

• addition, subtraction, multiplication and division

• works in conjunction with the other components of the CPU to run many complex processes

• A multi-core CPU can contain more than one ALU

Question 6

What is control unit on CPU?

Answer 6

•The Control Unit regulates the flow of information through the processor.

•receives, decodes, stores results and manages execution of data that flows through the CPU.

•determines how and when data is processed

•ensures that it is sent to the correct components of the computer

Question 7

What is registers on CPU?

Answer 7

Registers
•small pieces of memory located inside the CPU
•thought of as the hardware version of a variable in software
• The CPU contains a number of special-purpose registers

••General Purpose Registers••
o store any transient data required by the program.
• Eg when a program is interrupted its state
• the value of the registers such as the program counter, instruction register or memory address register - may be saved into the general purpose registers
• ready for recall when the program is ready to start again.
• In general the more registers a CPU has available, the faster it can work.

Question 8

What are CPU characteristics?

Answer 8

Characteristics of a CPU
•bit width
•clock cycles
•execution cores

bit width
•how many bits it processes in a single instruction or transports across the processor’s internal circuits (or busses in a single cycle.
• generally a multiple of 8
•it is possible for the registers and the busses to have different widths
•more bits means more processing capability and more speed
•Current processors use 64 bits.

Question 9

What are device drivers?

Answer 9

•When a manufacturer creates a new piece of hardware they will create a piece of software that talks to the operating system and passes data to and from the peripheral.

• pieces of software are called device drivers