Computer science feedback flashcards

1-64 unit 1.1

what is meant by a clock speed of 3.6 GHz?

Carries out 3.6 billion instructions per second

Which of the following tasks is the ALU not responsible for ?

Storing the results of a calculation

Which of the following is NOT a component of the CPU ? (1)

RAM (1)

Cache memory is part of the CPU.
What does cache memory enable the CPU to do ?

Store data to be transferred bac to RAM

Where does the CPU fetch instructions from?

RAM - Instructions to be executed are stored in RAM

Out of the following CPUs, which can carry out the most instructions per second ?

3 GHz quad core CPU

What is the fetch-decode-execute cycle?

the process that the CPU uses to carry out instructions

Where in the FDE cycle is an instruction converted into a format the CPU can use ?

Decode

During program execution, the CPU checks the address in the program Counter.
What is the address that is stored ?

Address in RAM of the next instruction

The CPU is made up of a number of different components, including registers. 
What are registers ?

small, high-speed storage locations within the CPU temporarily hold data and instructions for processing.

In the Von Neumann architecture of a computer system, which of the following components is used for storing data and instructions ?

RAM

In a computer system, which of the following is an example of a primary storage device ?

RAM

what is primary storage

the component of the computer that holds data, programs and instructions that are currently in use.

list the types of primary storage

ROM, RAM, flash memory, cache memory

how does a program counter work?

Holds the address of the next instruction to be processed. Passes the address to the MAR

Which number represents the MAR?

5

Which number represents the PC (program counter)?

3

Which number represents the MDR?

2

Which number represents the ACC?

6

Which number represents the address bus?

4

which number represents the data bus?

1

What is the purpose of the address bus?

Transfers the address to read/write data to/from from MAR to memory 

what is the purpose of the data bus?

transfers data between the main memory and the MDR

What is the purpose of the PC (program counter)?

holds the address of the next instruction to be fetched from memory

what is the purpose of the ACC?

holds/stores the results of calculations made by the ALU

What is the purpose of the MAR?

Holds the address to read/write data to/from

What is the purpose of the MDR?

holds the data that has been read from memory or is about to be written to memory

What is the CPU?

The CPU is an internal piece of hardware that is responsible for executing/processing the instructions of programs 

What happens during the fetch part of the FDE cycle?

The CPU gets the next instructions to be processed from main memory 

What happens during the “decode” part of the FDE cycle?

The CPU examines the instruction that has been fetched and works out what action needs to be taken e.g. adding, subtracting, storing or loading

What happens during the execute part of the FDE cycle?

The CPU actually carries out the instruction e.g. it loads the data, it stores the data etc 

List the components of a Von Newman Architecture

A Processor/ CPU, a memory unit, connections for input devices, connections for output devices

What component of the CPU is represented by number 1?

Processor

What component of the CPU is represented by number 2?

input

What component of the CPU is represented by number 3?

output

What component of the CPU is represented by number 4?

storage (cache)

how many memory units does the Von Newman architecture have?

The Von Neumann architecture has 2 memory units - one for instructions and one for data 

What are registers?

Registers are locations of computer memory on the CPU that provide extremely fast access and store data temporarily

How do you think the clock speed of a CPU would affect the performance of a computer

it would determine how  many FDE cycles can be completed by the CPU in a second, and therefore how fast the computer can run without overheating- a higher clock speed means the computer can run faster without overheating 

How many fetch decode execute cycles can a single core CPU execute at one time? 

3 billion

What are the key factors that govern the performance of the CPU in a computer?

lots of cache means lots of data can be transferred quicker to the processor; 

Higher clock speed means more processes are executed per second; 

Having more cores increases the clock speed since more cycles are being processed at once because there are more cores processing at the same time

according to the Von Neumann model, what are stored in memory?

data and instructions

explain what happens in the 'fetch' section of the Fetch Decode Execute cycle

The instruction and data required are fetched from RAM

what is the purpose of a ‘bus” in Von Neumann architecture?

to transfer instructions and data between the CPU and main memory

Which component acts as an intermediary between the processor and the main memory during the FDE cycle

Cache

state two advantages of using Von Neumann architecture

simplifies the design of the CPU

data and instructions are stored in the same area of memory so less components are required

Which of the following is NOT a benefit of more cores in a CPU ?

Processing data independantly

The CPU's first step is to fetch the next instruction to be executed.
The CPU will copy the memory address from where ?

The Program Counter (PC)

What is the role of the MAR register in the Von Neumann architecture?

Holds any of the memory addresses that are about to be used by the CPU

Which statement is a possible action during the 'execute' stage of the FDE cycle ?

The instruction stored in the MDR is decoded

What is the Control Unit (CU)?

a component of the CPU that synchronises data flow around the CPU

What is the Arithmetic and Logic Unit (ALU)?

a component of the CPU that performs mathematical and logical operations

list the registers on a CPU

Program counter, MAR, Address bus, data bus, MDR, ACC

identify parts of a computer that could improve the performance of a computer

Clock speed, cache size, number of cores, RAM, SSD, HDD, graphics card

explain one reason why the cache size affects the performance of the CPU

data is transferred faster which makes the CPU more efficient

List the events that take place in the Fetch Decode Execute cycle

the address of the next instruction to be fetched from memory is sent from the PC to the MAR;

the PC increments by 1;

an instruction is fetched from memory and placed on the data bus and is carried to the processor and stored in the MDR;

the instruction is then decoded;

The decoded instruction is then executed so that the CPU performs continuously;

The process is repeated

what is an embedded system?

a computer system that is built into another device and has been created for one specific purpose.

list devices that contain embedded systems

dishwasher, MP3 player, washing machine, manufacturing equipment

list the characteristics of embedded systems

task specific

the task is performed in a certain time frame

do the same thing repeatedly

may respond to sensors

list the purposes/ advantages of embedded systems

to provide a specific, pre-defined function

cheaper than providing a full personal computer system

can be much smaller than a personal computer system

allows for a device to be automated/programmed

How does the number of cores affect the CPU’s performance?

More cores allow more instructions carried out simultaneously, and allow the processor to process more instructions at the same time. This allows batches of instructions to be executed more quickly, which allows for more programs to be run at the same time.

How does the clock speed affect the performance of the CPU?

A faster clock speed means more instructions carried out per second and so instructions are executed more quickly. This allows for more programs to be run at the same time. This also allows for more complex processing operations to be completed in real time.

What is level 1 (L1) Cache?

cache that is part of the CPU itself and is both the smallest and the fastest to access

What are L2 and L3 caches?

Extra caches built between the CPU and the RAM. L2 and L3 caches take slightly longer to access than L1.

what is volatile memory

memory where the data is lost when the power is switched off

what is non volatile memory

memory where the data remains when the power is switched off

list examples of volatile memory

RAM, cache

list examples of non-volatile memory

hard drive, ROM

what is the role of the hard drive?

a component of the main memory that holds the data not in use and when the computer is switched off; permanent storage

what is the role of cache

holds frequently used instructions, quicker to access than RAM

what is the role of RAM

holds data currently in use e.g. when a file is opened, this is moved from the HDD to RAM

what is the role of the CPU

this performs Fetch, Decode, Execute cycles to run programs on a computer

label the numbers on this diagram of parts of the main memory

1: CPU

2: Cache

3: RAM

4: Hard drive

5: Volatile Storage

6: Non Volatile Storage

what is flash memory

non-volatile, solid state memory that can be read from and written to

list characteristics of flash memory

non volatile - retains data when the power is turned off

solid state - contains no moving parts, making it an ideal storage medium for many modern devices e.g. smartphones, tablets

fast to access and write to, although not as fast when reading from or writing to RAM

requires little power, making it an ideal storage medium for many modern devices e.g. smartphones, tablets

also used as external secondary storage e.g. USB memory sticks and SSDs

define virtual memory

When RAM is full, a portion of the HDD (hard drive) is allocated to act like RAM. Data is moved between virtual memory and RAM when needed by the CPU.

What do you think would be the effect on the performance of the computer of using a lot of virtual memory rather than upgrading your RAM?  

Using a lot of virtual memory would reduce the performance of the computer because secondary storage (such as a hard drive or SSD) is much slower than RAM. This means programs would take longer to load and run

what is the definition and role of secondary storage?

permanent storage of instructions and data not in use by the processor. Stores the operating system, applications and data not in use. Read/write and non-volatile.

list types of optical storage

CD/R, CD/RW, DVD/R, DVD/RW

list uses for optical storage

music, films, archive files

list characteristics of optical storage

low capacity

slow access speed

high portability

prone to scratches

low cost

list characteristics of magnetic storage

example: hard disk drive

uses: operating system and applications

high capacity

medium data access speed

low portability (except for portable drives)

reliable but not durable

medium cost

list characteristics of solid state storage

examples: memory cards and solid state hard drive (SSD)

use: digital cameras and smartphones

medium capacity

high portability

reliable and durable

no moving parts

fast data access speed

hich cost

what is storage capacity

the amount of data a storage device is able to store

wht is storage speed

the read/write access speed of a storage device

what is storage portability

how easy it is to transport a given storage medium. e.g; solid state and optical storage are designed to be highly portable, whereas more traditional magnetic storage is designed to stay in place

what is storage durability

how resistant to damage and wear and tear a storage device is. Devices with low durability will wear out easily over time

ehst is storsge cost

the relative price of a storage medium on a cost per GB

Alicia is using a helmet mounted camera to record footage whilst snowboarding.  Suggest two reasons why a flash memory card is a good choice for secondary storage in this scenario, and two reasons why a hard disk would be unsuitable. 

A flash card is a good choice because: 

 - it is very lightweight and portable and small – is inside the camera so it won't be damaged by impacts 

 - it has sufficient storage capacity for long videos like recordings of snowboarding footage 

A hard disk is a bad choice because: 

 - it isn't durable and is damaged by impacts, which are inevitable when snowboarding 

•  It isn't portable and is large and heavy – not suitable to be attached to a helmet 

Gregg is considering whether to download games for his games console from an online store, or whether to purchase the physical disks instead. 

Give reasons why he may choose one option or another.  

Online store – console might not support disks, or disk reader may not work 

Physical disk – can be used in places without internet  

Matt wants to keep a backup of his photos, and is considering using DVD-R disks.  Give two advantages and two disadvantages of this method 

Advantages: 

 - cheap per GB 

 - can store lots of photos 

Disadvantages:

 - short lifespan 

 - can break/ get scratched easily