Chapter 3 : Data - representation and structure

Question 0

Binary Coded Decimal

Answer 0

Similar to Binary
Eg. 7 in BCD is 0111
7 5 in BCD is 0111 0101

Question 1

Binary

Answer 1

128 64 32 16 8 4 2 1

Question 2

Octal

Answer 2

512 64 8 1

Question 3

Hexadecimal

Answer 3

256 16 1

10 A
11 B

Question 4

Binary Addition

Answer 4

0 + 0 = 0
0 + 1 = 0
1 + 0 = 0
1 + 1 = 0 ( carry one )

Question 5

2’s Compliment

Answer 5

Can represent negative number

Eg. 1001 0001
= -128 + 16 + 1 = - 111

Question 6

Sign and magnitude form

Answer 6

0 represents +
1 represents -

Eg. 1001 0001
= - ( 16 + 1 = 17 )
= - 17

Question 8

Three main methods of character encoding

Answer 8

EBCDIC
ASCII
UNICODE

Question 9

Define EBCDIC

Answer 9

It Was originally used on punch card computers by IBM

Question 10

Define ASCII

Answer 10

All characters, punctuation and single numbers have their own assigned number

Question 11

Define UNICODE

Answer 11

It contains characters such as mandarin characters, Thai characters and symbols.

Question 12

Inputting methods

Answer 12

Form Design
Keyboard Entry
Voice Recognition
Barcodes
Optical Mark Recognition (OMR)
Optical Character Recognition (OCR)
Magnetic Ink Character Recognition (MICR)
Touch screen 
Picture Capture
Chip and PIN
Sensor 
Remote data logging

Question 13

Define Barcode

Answer 13

A series of black lines used to store a numerical value.
The thickness of each line represents a particular number.
The last number is always a check digit – printer and reader will be calculate then check against it

Question 14

Define Optical Mark Recognition (OMR)

Answer 14

OMR is based on a pre defined form.
The form will have specific parts for someone to fill out by putting a pencil mark in the correct box.
A special reader will then read in this form and tell what was marked.
Eg. multiple choice exams and registers

Question 15

Define Optical Character Recognition (OCR)

Answer 15

OCR converts printed media into digital form using a scanner
It produces a editable text file
The shapes of letters and numbers are compared to those stored in the memory and the computer will decide the order of the characters

Question 16

Define Magnetic Ink Character Recognition (MICR)

Answer 16

MICR uses ink containing iron oxide and specific fonts so they can be read in by a specialist reader.
The cheque number and account number are written on the bottom of the cheque using magnetic ink.
This can then be very quickly read in by the reader so it can be quickly processed by the banks.

Question 17

Define Sensor

Answer 17

Sensors can be found in mobile phones, cars, cookers and even games consoles.
A sensor will record some data from the physical environment

Question 18

Examples of Sensor

Answer 18

Pressure sensor
Accelerometers
luminance sensor (light)
Humidity sensor 
Infrared sensor

Question 19

Forms of output

Answer 19

Graphs
Reports
Interactive Presentations
Sound
Video
Images
Animations

Question 20

Validation and Verification

Answer 20

They are used to ensure any input provided by the user is as correct as it can be.

Question 21

Purpose of Validation

Answer 21

It occur before data is committed to storage

Question 22

Purpose of Verification

Answer 22

It occurs after data is committed to storage

Question 23

Validation Checks

Answer 23

Format check - Ensure data conforms to a set a rules. Eg. email addresses must contain @
Existence - ensure data exists
Check digit - barcodes
Type check - ensure that the input is of the correct data type

Question 24

Verification Checks

Answer 24

Proof reading - A human will read over the input to manually check.

Question 25

Differences between back up and archive

Answer 25

When files are backed up, the original data still remains on the system. Whereas with archiving, once a copy has been made, the original files are removed from the system.