Instructions and data are both held in main memory
A program checks whether a player's score is higher than the highest score so far. Which CPU component carries out this check?
The arithmetic logic unit
What does a CPU's clock speed measure?
The number of clock cycles it completes every second
The address bus is described as one way only. What does this mean?
Addresses are sent from the CPU to main memory
Which bus carries control signals around the computer?
Control bus
The CPU is carrying out a calculation. Where are the values it is working on held?
In registers inside the CPU
What is meant by von Neumann architecture?
A design in which the CPU can access both instructions and data from the same main memory
Which term describes a very fast storage location inside the CPU that holds a small amount of data while it is being worked on?
Register
What is meant by the arithmetic logic unit?
The part of the CPU that carries out arithmetic operations and logical comparisons
Which term describes the part of the CPU that coordinates the activities of the other components, decodes instructions and directs their execution?
Control unit
What is the purpose of the address bus?
It carries the address of the memory location that the CPU wants to read from or write to
A program is loaded from secondary storage and then run. Why must its instructions be in main memory?
The CPU can fetch instructions directly from main memory as they are needed
Which statement describes an embedded system?
A computer inside a larger device that performs one dedicated function
Where are the programs of an embedded system normally stored?
In ROM
Which of these devices is a general purpose machine rather than an embedded system?
A desktop computer
How does the processor speed of an embedded system usually compare with a general purpose machine?
It is typically slower
A student tries to install a new game onto a car's engine control unit. Why does this not work?
It has one fixed purpose and cannot install new software
Embedded systems are usually described as very reliable. Why is this?
They each run one fixed program with a single purpose
Why can the embedded system inside a washing machine be described as a computer?
It takes inputs, processes data and produces outputs
Which term describes a computer that is built into a larger device so that it can carry out one dedicated function?
Embedded system
What is meant by a microcontroller?
A single chip that contains a processor, RAM and ROM
Which term describes a computer that can run many different programs and can have new software installed?
General purpose machine
What does an embedded computer combine in one unit?
A processor, RAM, ROM and input and output devices
A dishwasher has to heat the water at the correct point in its wash cycle. What carries out this task?
An embedded system running its fixed program
A modern car contains many embedded systems. Which statement about them is correct?
Each one controls a different dedicated function in the car
A company is designing a new microwave. Why is an embedded system a better choice than a general purpose computer to control it?
It has one fixed purpose, so it is very reliable
What does RAM stand for?
Random Access Memory
RAM is described as volatile. What does this mean?
Its contents are lost when the power is switched off
Why is an application transferred into RAM when it is opened?
So the CPU can access its instructions faster than from secondary storage
Which statement correctly compares RAM with secondary storage?
RAM has a smaller capacity and costs more per gigabyte
A student is typing a document when the power fails. What happens to the work that has not been saved?
It is lost, because RAM cannot hold data without power
Which of these is a typical amount of RAM for a modern desktop computer?
16 GB
A computer keeps freezing, but restarting it usually solves the problem. Why does restarting help?
Restarting clears the contents of RAM
What happens to an application that is running when it is closed?
It is removed from RAM
Which term describes memory that loses the data it stores when the power supply is switched off?
Volatile memory
What is meant by RAM?
The main memory that holds the programs and data currently in use and is volatile
What is meant by non-volatile memory?
Memory that keeps the data it stores even when the power supply is switched off
What is meant by primary storage?
The fast memory that is directly accessible by the CPU and holds the programs and data currently in use
Which term describes the maximum amount of data that a memory device is able to store?
Capacity
A computer becomes slow when several applications are open at the same time, and speeds up again when some are closed. What is the most likely explanation?
There is not enough RAM to hold all of the open applications
A hard disk drive transfers data at about 160 MB per second, while RAM transfers data at over 20000 MB per second. Why does the CPU need the programs it runs to be in RAM?
So the CPU does not have to wait for data and instructions to arrive
A computer has been switched on and several programs are open. Which of these is held in RAM?
The parts of the applications that are currently in use
What is the main purpose of secondary storage in a computer system?
To store programs and data permanently when the power is off
How is data read from and written to a magnetic hard disk drive?
A read/write head moves over rotating magnetic platters
How does an optical drive read data from a CD?
A laser detects different levels of reflection from pits and lands
Which statement describes how solid state storage holds data?
Electrons are trapped in flash memory cells
A student wants a drive for a laptop that will keep working if the laptop is dropped. Which is most suitable?
A solid state drive, as it has no moving parts
A school checks how likely a backup drive is to lose data over several years. Which storage characteristic is being considered?
Reliability
Which is an advantage of magnetic hard disks compared with solid state drives?
They cost less for the same amount of storage
What is the name for the type of storage that keeps its data when the power is turned off?
Non-volatile storage
Which term describes the storage method that uses a laser to measure reflected light from a disc?
Optical storage
What is meant by 'capacity'?
The amount of data that a storage device is able to hold
Which term describes the method of recording data onto memory chips with no moving parts?
Solid state storage
What is meant by 'portability' when comparing secondary storage devices?
How easy a storage device is to carry around with you
What is the name for the concentric circles on a magnetic disk on which data is stored?
Tracks
Which term describes the rate at which data can be read from or written to a storage device, usually measured in MB/s?
Speed
Which type of memory is non-volatile, has no moving parts and is used in memory sticks and SD cards?
Flash memory
A film company needs to archive many years of footage at the lowest possible cost. Which type of secondary storage is most suitable?
Magnetic tape
Why do solid state drives usually read and write data faster than magnetic hard disks?
They do not have to wait for a disk to spin and a head to move
Which is a disadvantage of using optical discs such as DVDs to store data?
The data surface is easily scratched or damaged
A program is stored on a hard disk. Why must it be copied into RAM before the CPU can run it?
The CPU can only read data that is held in primary storage
What happens during the fetch stage of the cycle?
The next instruction is copied from main memory into the CPU
What is the role of the clock in the fetch-decode-execute cycle?
It sends regular signals that control the timing of the cycle
A program adds two numbers together and then compares the result with zero. Which component performs both of these operations during the execute stage?
The arithmetic logic unit
During the fetch stage, the CPU needs the instruction stored at address 20 of main memory. Which component carries this address to main memory?
The address bus
In the stored program concept, what does main memory hold while a program is running?
Both the program instructions and the data being used
Which term describes the step in which the next instruction is moved from main memory into the CPU?
Fetch
What is meant by the 'control unit'?
The part of the CPU that decodes instructions and directs the other components
What is meant by a 'register'?
A very fast storage location inside the CPU that holds values being worked on
Which term describes the step in which the control unit works out what an instruction means?
Decode
What is meant by main memory?
The store that holds the instructions and data currently in use by the CPU
During the fetch stage, main memory returns the instruction that the CPU has asked for. Which path carries that instruction from main memory into the CPU?
The data bus
Which path carries the signals that tell main memory whether the CPU wants to read a value or write a value?
The control bus
A program instruction stores the contents of a register into main memory. During which stage of the cycle does this happen?
Execute
A program must be copied into main memory before it can be run. Why is this?
Because the CPU fetches each instruction from main memory