Computer Organisation And Architecture

Question 1

Main memory

Answer 1

Includes RAM and ROM, is volatile memory that provides fast storage and retrieval of data

Question 2

Address Bus

Answer 2

Bus that carries identification about where data is being sent

Question 3

Data bus

Answer 3

Bus that carries the data and instruction to and from every component of the computer system

Question 4

Control Bus

Answer 4

Bus that carries command and control signals to and from every other component of a computer. Also carries the computer’s clock signal

Question 5

I/O Controller

Answer 5

Piece of hardware that controls the communication of data between the processor and the external hardware device such as keyboard, mice and monitors

Question 6

Width of bus

Answer 6

Number of parallel wires in a bus

Question 7

Bus

Answer 7

Series of parallel wires that connects internal components of a computer system, allowing for signals to be passed

Question 8

Increasing the width of address bus

Answer 8

Increases the range of adresses it can specify,hence increasing the computer’s amount of addressable memory. (2^n)

Question 9

Increasing width of data bus

Answer 9

Increases the number of bits that can be transferred at one time

Question 10

Harvard Architecture

Answer 10

Computer Architecture with physically seperate storage and signal pathways for instructions and data. Extensively used in embedded systems like digital signal processing.

Question 11

Von Neumann Architecture
(4 Points)

Answer 11

-Traditional computer architecture that forms the basis of most digital computer systems.
-A single control unit manages program control flow following a linear sequence of fetch decode execute.
-Both instructions and data are stored together in the same memory and therefore often performs worse than harvard as the same bsuses have to be shared for fetching both.
-Used in everyday general purpose computer systems like phones

Question 12

ALU

Answer 12

Arithmetic logic unit is the part of the CPU where data is processed and manipulated. This processing and manipulation normally consists of arithmetic operations or logical comparisons allowing a program to make decisions

Question 13

Control Unit

Answer 13

Responsible for controlling the various components of the processor

Question 14

Stored Program Concept

Answer 14

Serially fetching and executing machine code instructions stored in main memory by a processor that perfroms arithmetic and logical operations.

Question 15

Clock

Answer 15

Frequenzt ar which the internal clock generates pulses, measured in hertz. The generated pulses synchronise related components

Question 16

General purpose register

Answer 16

Small storage locations used to hold data temporarily. They have high read and write speeds

Question 17

Program Counter (PC) purpose

Answer 17

Used to hold the memory address of the next instruction to be executed in the fetch execute cycle

Question 18

Current Instruction Register (CIR) purpose

Answer 18

Holds the instruction that is currently being executed by the processor

Question 19

Memory Address Register (MAR)

Answer 19

Stores the memory address of a memory location that is to be read fron or written to.

Question 20

Memory Buffer Register (MBR)

Answer 20

Holds the contents of a memory location that has been read from or data that is to be stored. Also called Memory Data Register

Question 21

Status Register (SR)

Answer 21

Contains a number of bits, the values of which can chnage to indicate the occurrence of an interrupt

Question 22

Opcode

Answer 22

It is the portion of a machine instruction which specifies the operation to be performed

Question 23

Operand

Answer 23

The portion of a machine instruction which specifies the operation to be performed.

Question 24

Interrupt

Answer 24

A signal generated by a source such as hardware or software that causes a break in the execution of the current routine.

Question 25

Processor Instruction Set

Answer 25

Group of commands for a CPU in machine language. Each type of process has its own instruction set.

Question 26

Immediate Addressing

Answer 26

Uses the data in the address field as a constant required by the program and not as an address.

Question 27

Direct Addressing

Answer 27

The value specified by the operand signifies a memory address.

Question 28

Mnemonic

Answer 28

In assembly language, a mnemonic is an abbreviation for an operation

Question 29

Interrupt Service Routine (ISR)

Answer 29

Software routine that hardware invokes in response to an interrupt

Question 30

Factors affecting processor performance (6)

Answer 30

-Number of Cores
-Cache Memory
-Clock Speed
-Word Length
-Address Bus WIdth
-Data Bus Width

Question 31

How does the number of cores affect processor performance?

Answer 31

Each core can perform its own fetch-execute cycle independently

Question 32

How does the cache memory affect processor performance?

Answer 32

Cache is used to store frequently used information and reduces time wasted in fetching the same information from main memory time and time again.

Question 33

How does the clock speed affect processor performance?

Answer 33

The higher the frequency, the more cycles of the fetch-execute cycle can be completed in the same period of time. However, errors can occur when a computer’s clock speed is increased too far

Question 34

Barcode

Answer 34

Printed diagram that consist of light and dark portions. They contain information. The pattern of light and dark striped in a barcode corresponds to binary. Barcodes can have error detection and prevention methods such as parity bits and check digits built in.

Question 35

2D vs 1D barcode

Answer 35

2D barcodes contain more information in the same amount of space as a 1D barcode but require more processing in order for the information to be extracted

Question 36

Barcode Readers

Answer 36

Consist of a laser light source, a lens, photodiodes and a mirror. The mirrot directs light from the laser onto a printed barcode. The light reflected by the barcode passes through the lens and is incident on the photodiode which turns light into electrical charge. This electrical charge can be measured and processesd to form a digital signal representing the content of a barcode.

Question 37

Digital camera

Answer 37

Consists of a lens that focuses light onto a sensor. The path of light between the lens and the sensor is regualted by a shutter.

Question 38

Sensors

Answer 38

-Complementary Metal Oxide Semiconductor (CMOS)
-Charge Couples Device (CCD)
-Both convertincident light into electrical charge, Charge build up in cells, each of which represents a pixel in the image. Once a photograph has been taken, the charge in each cell is measured and converted to a digital value which is then processed by the camera and stored as a digital image.

Question 39

Colour cameras

Answer 39

There are multiple cells for each pixel, each of which has a filter that only allows in certain wavelengths of light. This lets the camera build up a seperate image for the intensity of each colour which can then be combined to form a full colour photograph.

Question 40

Bayer filter

Answer 40

Special colour filter used in digital camaras that has the same number of green filters as red and blue combined. Using a bayer filter produces an image that is a closer approximation of what the human eye sees as its mose senstive to green light.

Question 41

Laser Printer

Answer 41

Output device that produces images on paper from digital signals. They consist of a laser light source, a mirror, a drum, a toner roller and fusers.

Question 42

Laser Printer Method

Answer 42

When a document is printed, a bitmap of image built in memory from page description. The drum is negatively charged all over before the laser is directed at its surface by the mirror. Areas on which the laser is incident are discharged, leaving behing an impression of the page in electrical charge on the drum. The toner roller dispenses negatively charged toner (type of plastic powder) onto the drum. As opposite charges attract, toner is attracted to the positively charged portions of the drum. Positively charged transfer roller assists transfer toner from drum to paper. The toner is then applied to the paper by the drum before the paper is heared by fusers, fixing the toner to the paper.

Question 43

Radio Frequency Identification (RFID)

Answer 43

Method of transferring information wirelessly between a tag and a reader. Used in contactless credit and debit cards. Inside an RFID tag is a chip which contains a small amount of memory. Chip is attached to a coil of wire which acts as an antenna.

Question 44

Secondary Storage

Answer 44

Non-volatile memory that is not directly accessible by the CPU, as its not accessed through the input/output channel because it is an external device.

Question 45

Hard Disk Drives

Answer 45

Consits of a number of circular platters which are made from a magnetic material. Above each platter hovers an actuating arm on which is a read/write head. The actuating arm allows the head, which changes the magnetic polarity of parts of the platter, to access all portions of each platter

Question 46

HDD method

Answer 46

Data is written in concentric tracks, each of whihc is further divided into sectors. The platter rotates thousands of times per minute, allowing for good read and write speeds.
Because of the number of moving parts, they are susceptible to damage from movement. This makes them unsuitable for use in portable devices like phones.

Question 47

Two ways in which hard disk drices can be kept the same size while increasing their capacity

Answer 47

-Adding more platters
-Decreasing the width of tracks

Question 48

Solid State drives ( SSD )

Answer 48

Consist of NAND flash memory cells and a controller that manages the structure of data on the drive. Data is stored in SSDs in pages, which are combined to form blocks.

Question 49

NAND flash memory

Answer 49

Non volatile. The memory cells are formed of floating gate transistors which store information by trapping electrical charge.

Question 50

Disadvantage of SSD

Answer 50

Not capable of overwriting data instead, an SSD’s controller must completely erase the entorety of a page before writting new information on it.

Question 51

Advantage of SSD

Answer 51

No moving parts, so are capable of far higher read and write speeds than HDDs and are suitable for use in portable devices like phones and tablets.