1.1 - CHARACTERISTICS OF CONTEMPORARY PROCESSORS, INPUT, OUTPUT AND STORAGE DEVICES.

Question 1

What is the processor?

Answer 1

The brain of a computer. It executes instructions which allows programs
to run.

Question 2

What is the ALU (Arithmetic Logic Unit) ?

Answer 2

The ALU (Arithmetic and Logic Unit) completes all of the arithmetical and logical
operations. Arithmetical operations include all mathematical operations such as addition
and subtraction on fixed or floating point numbers. Logical operations include boolean
logic operations such as AND, OR, NOT, and XOR.

Question 3

What is the CU (Control Unit) ?

Answer 3

The Control Unit is the component of the processor which directs the operations of the
CPU. It has the following jobs:
- Controlling and coordinating the activities of the CPU
- Managing the flow of data between the CPU and other devices
- Accepting the next instruction
- Decoding instructions
- Storing the resulting data back in memory

Question 4

What are Registers?

Answer 4

Registers are small memory cells that operate at a very high speed. They are used to
temporarily store data and all arithmetic, logical and shift operations occur in these
registers.

Question 5

Name 5 Registers.

Answer 5

PC - Program Counter
ACC - Accumulator
MAR - Memory Address Register
MDR - Memory Data Register
CIR - Current Instruction Register

Question 6

What is the PC (Program Counter) ?

Answer 6

Register - Holds the address of the next instruction to
be executed.

Question 7

What is the ACC (Accumulator) ?

Answer 7

Register - Stores the results from calculations

Question 8

What is the MAR (Memory Address Register) ?

Answer 8

Register - Holds the address of a location that is to be
read from or written to.

Question 9

What is the MDR (Memory Data Register) ?

Answer 9

Register - Temporarily stores data that has been read
or data that needs to be written.

Question 10

What is the CIR (Current Instruction Register) ?

Answer 10

Register - Holds the current instruction being
executed, divided up into operand and
opcode.

Question 11

What are buses?

Answer 11

Buses are a set of parallel wires which connect two or more components inside the CPU.

Question 12

What are three types of buses?

Answer 12

There are three buses in the CPU: data bus, control bus, and address bus.

Question 13

What are the system buses?

Answer 13

There are three buses in the CPU: data bus, control bus, and address bus. These buses
collectively are called the system bus.

Question 14

What is the width of the bus?

Answer 14

The width of the bus is the number of parallel wires the bus has. The width of the bus is
directly proportional to the number of bits that can be transferred simultaneously at any
given time. buses are typically 8, 16, 32 or 64 wires wide.

Question 15

What is the data bus?

Answer 15

This is a bi-directional bus (meaning bits can be carried in both directions). This is used for
transporting data and instructions between components.

Question 16

What is the address bus?

Answer 16

This is the bus used to transmit the memory addresses specifying where data is to be sent
to or retrieved from. The width of the address bus is proportional to the number of
addressable memory locations.

Question 17

What is the control bus?

Answer 17

This is a bi-directional bus used to transmit control signals between internal and external
components. The control bus coordinates the use of the address and data buses and
provides status information between system components.

Question 18

What are examples of control signals?

Answer 18

• Bus request: shows that a device is requesting the use of the data bus
• Bus grant: shows that the CPU has granted access to the data bus
• Memory write: data is written into the addressed location using this bus
• Memory read: data is read from a specific location to be placed onto the data bus,
• Interrupt request: shows that a device is requesting access to the CPU
• Clock: used to synchronise operations

Question 19

What is assembly code?

Answer 19

Assembly code uses mnemonics to represent instructions,
for example ADD represents addition. This is a simplified
way of representing machine code.

Question 20

What is an instruction divided into?

Answer 20

The instruction is divided into operand and opcode in the
Current Instruction Register.

Question 21

What is OPERAND?

Answer 21

The operand contains the data
or the address of the data upon which the operation is to be
performed.

Question 22

What is OPCODE?

Answer 22

The opcode specifies the type of instruction to
be executed.

Question 23

What is pipelining?

Answer 23

Pipelining is the process of completing the fetch, decode, and execute cycles of three
separate instructions simultaneously, holding appropriate data in a buffer in close proximity
to the CPU until it’s required. While one instruction is being executed, another can be
decoded and another fetched.

Question 24

What does pipelining aim to reduce?

Answer 24

Pipelining is aimed to reduce the amount of the CPU which is kept idle. It is separated into
instruction pipelining and arithmetic pipelining.

Question 25

What is instruction pipelining?

Answer 25

Instruction pipelining is separating out the instruction into fetching, decoding, and executing.

Question 26

What is arithmetic pipelining?

Answer 26

Arithmetic pipelining is breaking down the arithmetic operations and overlapping them as they are performed.

Question 27

What is the FDE Cycle?

Answer 27

The fetch-decode-execute cycle is the sequence of operations that are completed in order to execute an instruction.

Question 28

What is the fetch stage?

Answer 28

Fetch phase: - Address from the PC is copied to the MAR - Instruction held at that address is copied to MDR by the data bus - Simultaneously, the contents of the PC are increased by 1 - The value held in the MDR is copied to the CIR

Question 29

What is the decode stage?

Answer 29

Decode phase: - The contents of CIR are split into operand and opcode

Question 30

What is the execute stage?

Answer 30

Execute phase: - The decoded instruction is executed

Question 31

What are the three factors affecting the FDE Cycle?

Answer 31

There are three factors that affect CPU performance: clock speed, number of cores and the amount and type of cache memory.

Question 32

What is clock speed?

Answer 32

The clock speed is determined by the system clock. This is an electronic device which generates signals, switching between 0 and 1. All processor activities begin on a clock pulse, and each CPU operation starts as the clock changes from 0 to 1. The clock speed is the time taken for one clock cycle to complete.

Question 33

What are the number of cores?

Answer 33

A core is an independent processor that is able to run its own fetch-execute cycle. A computer with multiple cores can complete more than one fetch-execute cycle at any given time.

Question 34

What is cache memory?

Answer 34

Cache memory is the CPU’s onboard memory. Instructions fetched from main memory are copied to the cache, so if required again, they can be accessed quicker. As cache fills up, unused instructions are replaced.

Question 35

What is cache level 1?

Answer 35

Very fast memory cells with a small capacity. (2-64KB)

Question 36

What is cache level 2?

Answer 36

Relatively fast memory cell, with a medium sized capacity. (256KB-2MB)

Question 37

What is cache level 3 ?

Answer 37

Much larger and slower memory cell.

Question 38

What is Von Neumann Architecture?

Answer 38

This architecture includes the basic components of the computer and processor (single control unit, ALU, registers and memory units) in which a shared memory and shared data bus is used for both data and instructions. Von Neumann architecture is built on the stored program concept.

Question 39

What is Harvard Architecture?

Answer 39

Harvard architecture has physically separate memories for instructions and data, more commonly used with embedded processors. This is useful for when memories have different characteristics This also allows you to optimize the size of individual memory cells and their buses depending on your needs.

Question 40

What are the advantages of the Von Neumann Architecture?

Answer 40

Cheaper to develop as the control unit is easier to design. Programs can be optimised in size

Question 41

What are the advantages of the Harvard Architecture?

Answer 41

Quicker execution as data and instructions can be fetched in parallel. Memories can be different sizes, which can make more efficient use of space

Question 42

What is contemporary processing?

Answer 42

Contemporary processors use a combination of Harvard and Von Neumann architecture. Von Neumann is used when working with data and instructions in main memory, but uses Harvard architecture to divide the cache into instruction cache and data cache.

Question 43

What is a RISC (Reduced Instruction Set Computer) ?

Answer 43

In these processors, there is a small instruction set. Each instruction is approximately one line of machine code and takes one clock cycle

Question 44

What is a CISC (Complex Instruction Set Computer) ?

Answer 44

In these processors there is a large instruction set. The aim is to try and accomplish tasks in as few lines of assembly code as possible. These instructions are built into the hardware.

Question 45

What is a multi-core CPU?

Answer 45

Multi-core CPUs have multiple independent cores that can complete instructions separately which results in higher performance.

Question 46

What are parallel systems?

Answer 46

Parallel systems accomplish a similar task however instead of requiring multiple cores they can complete tasks with a single core, by using threading. Generally, multi-core systems perform better in larger projects than parallel systems.

Question 47

What is a GPU (Graphic Processing Unit) ?

Answer 47

A graphics processing unit (GPU) is a device which unlike CPUs has lots of independent processors which work in parallel making it very efficient at completing repetitive tasks such as image processing and machine learning.

Question 48

What is a co-processor?

Answer 48

a secondary processor designed to supplement the activities of the primary processor - GPU

Question 49

What is an input device?

Answer 49

An input device is one which can be used to put data and information into a computer.

Question 50

What is an output device?

Answer 50

An output device is one which can be used to send information from the computer.

Question 51

What is optical storage?

Answer 51

Optical devices are read from and written to using lasers. Binary information is represented by portions of the disc which either reflect or scatter the incident laser light written in spiral tracks on the disc’s surface. A microscopic view of the surface of a CD. The portions which are recessed, called pits, scatter light whereas the flat portions, called lands, reflect light. Pits represent a 0 and lands represent a 1.

Question 52

What is a CD?

Answer 52

CD stands for compact disc. They use optical technology to store small quantities of information. Most commonly used for audio files, CDs can also be used to store text and digital images.

Question 53

What is a DVD?

Answer 53

DVD stands for digital versatile disc or digital video disc. Similar to CDs, DVDs are also optical devices which have a higher storage capacity than CDs, making them suited to storing digital videos which require more storage space than audio files or photos.

Question 54

What are the characteristics of a CD?

Answer 54

CDs are small, thin and light which makes them very portable.

Question 55

How does a Blue-Ray Disc differ to a CD?

Answer 55

An advancement over DVDs, blu-ray discs have more than five times as much storage than traditional DVDs, making them useful for storing high-resolution films.

Question 56

How does magnetic storage work?

Answer 56

Devices which store information magnetically represent binary information using two magnetic states.

Question 57

What are the two types of magnetic storage?

Answer 57

Polarised and unpolarised.

Question 58

If a magnetic area is polarised, what happens?

Answer 58

If a portion of magnetic material is polarised, all magnetic poles align and can be read by a read/write head passing over the region.

Question 59

If a magnetic area is unpolarised, what happens?

Answer 59

If an area is not polarised, magnetic poles are randomly scattered and produce a different reading on a read/write head. These two states can represent 1 and 0, allowing any information to be represented in binary form.

Question 60

How does a Hark Disk Drive work?

Answer 60

They work by rotating magnetic platters at high speeds under a read/write head on an actuating arm. The combination of the arm and rotating platter allows the read/write head to access any part of the platter.

Question 61

How do HDD's maximize storage?

Answer 61

Most HDDs will have multiple platters stacked on top of each other to maximise storage capacity.

Question 62

What are the disadvantages of HDD's?

Answer 62

Disadvantages of HDDs include their somewhat slow data transfer speeds and their tendency to become damaged by movement. The combination of brittle platters and moving parts results in a delicate device.

Question 63

What is magnetic tape?

Answer 63

First used to record computer data in the 1950s, magnetic tape was a popular storage medium right through to the 1980s. Wound onto reels, long stretches of tape were passed through readers which would check the polarity of the tape and read off a binary value.

Question 64

What are the disadvantages of magnetic tape?

Answer 64

Tape was a bulky way to store data, and although improvements were made by reducing the width of the tape and writing in diagonal lines as opposed to horizontal tracks, the technology was superseded by more modern technology like ROM cartridges.

Question 65

What is flash storage?

Answer 65

Flash storage is fast and compact. The technology makes use of silicon semiconductors forming the logic gates NAND and NOR to store electrical charge in one of two states: high or low. These two states represent the binary values True and False, which can be used to represent information.

Question 66

What are Solid State Drives?

Answer 66

They are extremely light and portable, while having no moving parts - this makes them much more resistant to damage from movement than hard disk drives, which are packed with moving parts. Furthermore, SSDs are renowned for their high data transfer rates.

Question 67

What are the disadvantages of SSD's?

Answer 67

The primary disadvantage of SSDs is their cost, which continues to decrease as they become more common. Another disadvantage is their limited lifespan. Every time a page is written to, the voltage required to write to it increases. Over time, this required voltage will become too high for the page to be written to

Question 68

What is Random Access Storage?

Answer 68

Random access memory is a type of fast main memory used to store data and programs that the computer is currently using. This speeds up the computer’s execution as RAM has higher access speeds than even flash memory.

Question 69

Is RAM volatile or non-volatile?

Answer 69

RAM is volatile, meaning that it loses its information when power is lost. For this reason, RAM isn’t used for storing personal files but as temporary storage while the computer is running

Question 70

What is Read Only Memory?

Answer 70

Read only memory, as the name suggests, cannot be modified. Once programmed, the state of the memory cells inside does not changed. ROM is useful for storing fixed sequences of instructions like a computer’s startup (bootstrap) routine. ROM is non-volatile, so it retains its data even when the computer is powered off.

Question 71

What is Virtual Storage?

Answer 71

Virtual storage is the name given to storing information remotely so that it can be accessed by any computer with access to the same system, for example over the Internet. Examples of virtual storage include cloud storage services like Google Drive and Microsoft OneDrive as well as networked storage used in offices and schools.