Topic 1: The characteristics of contemporary processors, input, output and storage devices

Question 1

What are the 2 Architectures of the Computer

Answer 1

Von Neumann Architecture

Harvard Architecture

Question 2

What is Von Neumann Architecture

Answer 2

Has one control unit, ALU, registers and memory unit with a shared memory and data bus used for data and instructions.

Question 3

What is Harvard Architecture

Answer 3

Has separate memories for instructions and data. It is more commonly used in embedded processors

Question 4

Compare Harvard and Von Neumann Architectures

Answer 4

• Von Neumann Architecture is cheaper to develop as the control unit is simpler and allows programs to be optimised in size.
• Harvard Architecture allows data and instructions can be fetched in parallel and both memories can be different sizes.

Question 5

What is Contemporary Processing

Answer 5

• Combines Harvard and Von Neumann architecture
• Von Neumann is used when working with data and instructions in main memory
• Harvard is used when working with cache.
• Has a separate instruction and data cache.

Question 6

What is RAM

Answer 6

Random Access Memory
* Volatile
* Holds data and programs which are currently in use
* High access speeds
* Very expensive per gigabyte

Question 7

What is ROM

Answer 7

Read Only Memory
* Non-volatile (Cannot be modified)
* Used to store fixed instructions such as the computer start up routine

Question 8

What is a Multi-core System

Answer 8

Multi-core CPUs have many cores which complete separate fetch-execute cycles independently.

Question 9

What are Parallel Systems

Answer 9

Parallel systems can carry out multiple instructions simultaneously using a single core using techniques like pipelining.

Question 10

Steps of the Fetch stage of FDE Cycle

Answer 10

o Address copied from the PC to the MAR.
o Data bus copies the instruction from that location to the MDR
o At the same time, the contents of the PC increase by 1
o The value is them copied from the MDR to the CIR

Question 11

Steps of Decode stage of the FDE cycle

Answer 11

Contents of the CIR are split into operand and opcode

Question 12

Steps of Execute stage of the FDE cycle

Answer 12

The opcode is executed on the operand

Question 13

What is the Opcode

Answer 13

The type of instruction and the hardware to execute it

Question 14

What is Operand

Answer 14

The address where the operation is performed

Question 15

Name the 5 registers:

Answer 15

• PC (Program Counter)
• ACC (Accumulator)
• MAR (Memory Address Register)
• MDR (Memory Data Register)
• CIR (Current Instruction Register)

Question 16

Name the 3 buses

Answer 16

• Data bus
• Address bus
• Control bus

Question 17

What is the PC

Answer 17

Stores the address of the next instruction to be executed

Question 18

What’s the ACC

Answer 18

Stores the results of calculations

Question 19

What’s the MAR

Answer 19

Holds the address in memory that that is to be written to or read from

Question 20

What’s the MDR

Answer 20

Holds data which has been read or needs to be written

Question 21

What’s the CIR

Answer 21

Stores the current instruction, split into operand and opcode

Question 22

What are Buses

Answer 22

• Parallel wires connecting two or more CPU components together
• The number of wires determine the width
• The System bus contains the data bus, control bus and address bus

Question 23

What is the ALU

Answer 23

Arithmetic Logic Unit
Carries out arithmetic and logical operations

Question 24

What is the CU

Answer 24

Control Unit
Directs operations inside the processor

Question 25

What are registers

Answer 25

Small, fast memory cells used to temporarily store data

Question 26

What is Flash Storage

Answer 26

* Fast and compact * Logic gates store an electrical charge * High represents a binary 1 * Low represents a binary 0 * Information is stored in blocks which are combined to form pages * More expensive * Limited lifespan

Question 27

What are SSD

Answer 27

Solid State Drives * Light and portable * No moving parts * More resistant to damage from movement than hard disk drives * High data transfer rates * Smaller capacity than hard disk drives

Question 28

What is Virtual Storage

Answer 28

* A method of storing information remotely. * Allows multiple computers to access data over a network or The Internet. * Includes cloud storage and network accessible storage. * Becoming more popular as network and Internet speeds increase. * Relies on a network connection for access to data. * Limited by network speed.

Question 29

What is Virtual storage limited by

Answer 29

Network Speed

Question 30

What Is Magnetic Storage

Answer 30

* Two magnetic states represent binary o Polarised sectors represent 1 o Unpolarised sectors represent 0 * Can be damaged by strong magnets

Question 31

Features of Hard Disk Drives

Answer 31

* High capacity * Magnetic platters rotate at high speeds beneath a read/write head * Multiple platters are stacked to maximise storage capacity * Moving parts can become damaged

Question 32

Features of Magnetic Tape

Answer 32

* An older storage medium * Tape is round onto reels within a cartridge * The tape drive spins the reels to move the tape across a reader

Question 33

Features of Floppy Disks

Answer 33

* A thin magnetic disk in a plastic case. * Small and portable * Typical storage capacity of 1MB

Question 34

What's an Input device

Answer 34

Input devices are used to send data to the computer, such as a keyboard, mouse or sensor.

Question 35

What's and Output Device

Answer 35

Output devices allow the computer to send information out, such as a speaker or screen.

Question 36

What is RISC

Answer 36

Reduced Instruction Set Computers * Small instruction set * One instruction is one line of machine code * Used in personal computers

Question 37

What is CISC

Answer 37

Complex Instruction Set Computers * Large instruction set * Instructions built into hardware * Used in microcontrollers and embedded systems * Compiler has less work to do * Less RAM is needed to store the code

Question 38

How does Optical Storage work

Answer 38

* Use lasers to read and write to a disk. * Sectors of the disc are written in a spiral. o Pits scatters light representing 0 o Lands reflects light representing 1

Question 39

Disadvantages of Optical Storage

Answer 39

* Small and light so very portable * Easily scratched * Not very fast

Question 40

Features of a CD

Answer 40

Compact disk Commonly used for audio but can store any data type Stores relatively little information

Question 41

Features of a DVD

Answer 41

Digital Versatile Disk Higher storage capacity than CDs Often used to store videos

Question 42

Features of Blu-ray

Answer 42

More than 5x as much storage as DVDs Used to store HD films

Question 43

What is Pipelining

Answer 43

* Allows three instructions to be processed through the fetch, decode and execute cycle at the same time. * Data is stored in a buffer close to the CPU until required. * Whilst one instruction is being executed, another can be decoded and another fetched. * Reduces the amount of CPU idle time.

Question 44

What's a GPU

Answer 44

Graphics Processing Unit * Had multiple processors working in parallel. * Efficiently completes repetitive tasks. * Used for image processing and machine learning. * A co-processor (a secondary processor which supports the activities of the primary processor)

Question 45

3 Factors that affect CPU performance

Answer 45

- Clock Speed - Number of Cores - Amount and Type of Cache Memory

Question 46

What is Clock Speed

Answer 46

* Determined by the system clock * All activities begin on a clock pulse * Each operation starts when the clock changes from 0 to 1 * The clock speed is the number of clock cycles which can be completed in a second. * Faster clock speed = better performance

Question 47

What is Number of Cores

Answer 47

* Each core is an independent processor which executes its own fetch-execute cycle * CPUs with several cores can complete more than one fetch-execute cycle at the same time * Some applications can only use one core. * More cores = better performance

Question 48

What is the Amount and Type of Cache Memory

Answer 48

* Cache memory is fast memory built into the CPU * Instructions are held in cache allowing them to be accessed quickly if needed. * As cache fills up, unused instructions are overwritten. * More cache = better performance * Cache can be Level 1, 2, or 3 * Level 1 is the fastest but smallest * Level 3 is the slowest but largest