Chapter 1

Question 1

benifits of bcd

Answer 1

-more straightforward to convert between bcd and denary
-less complex to encode and decode for programmwrs
-easier for digital equipement to use bcd to display information
-can display monetary values exactly

Question 2

Applications of BCD

Answer 2

-Electronics displays (calcs, digital clocks) only need to showindividual digits, conversion between denary and bcdeasier.
-storage of date and time in BIOS in PC, conversion with denary easier

Question 3

Applications of hexademical

Answer 3

-MAC Address
-HTML color codes
-can be used to refer to memory address in assembly language and in machine code

Question 4

ASCII representation

Answer 4

-each character has a unique code
-character is replaced by its corresponding code
-codes stored in same order as in the word

Question 5

Character Set (Asci, Unicode, Extended Ascii)

Answer 5

-all characters that a computer can represent/use
-each character has a unique corresponding binary number

SIMILARITIES
-All can use 8 bits
-Ascii is a subset of unicode
-each represent a character using a unique code

Differences
-Unicodee can represent multiple languages with a wider range than Ascii
-Ascii- 7 bit, extended Ascii-8 bit Unicode- 16 bit

Question 6

Bitmap Graphics

Answer 6

-made up of pixels each of a single color (each color with unique binary
-stored as a sequence of binary numbers(store binary value of each pixel)
-prone to pixelation when enlarged
-larger file size=larger data stored on each pixel
-can be compressed significantly
-more difficult to edit, each pixel needs to be edited seperately

Question 7

Pixel

Answer 7

-The smallest addressable element in an image

Question 8

File Header

Answer 8

-stores metadata about bitmap image (color depth, image resolution)
-can store file type, compression type dimensions(width x height), file size

Question 9

Image Resolution

Answer 9

-total number of pixels in an image(no. pixels in width x no. pixels in height)
-Increasing resolution, more pixels stored ,sharper image

Question 10

Bit-depth/color depth

Answer 10

-the numbr of bits used to represent each color//bits per pixel
-determines numbers of colors that can be represented in an image
-increase in bit depth, has greater range colors, closer to original, larger file size
-

Question 11

Vector Graphics

Answer 11

-Encoded as a series of geometric shapes
-stored coordinates of drawing objects in image
-cotains drawing list (commands for creating each individual objects and their attributes)

Question 12

Sound Representation

Answer 12

-Amplitude is recorded a set number of times in a second
-each amplitude is given a unique corresponding binary value
-binary value save din a sequence

Question 13

Sampling

Answer 13

-taking measurements at regular intervals and storing them

Question 14

Sampling Rate

Answer 14

-number of samples taken pen unit time

Question 15

Effect of increasing sampling rate

Answer 15

-sound recorded more often//small gaps between sound waves and samples
-reduces quantisation errors
-improves accuracy, digital waveform represents analogue waveform more closely
-Increased file size, more total sample taken, so more bits take up storage

Question 15

Sampling Resolution

Answer 15

-Number of bits used to store each sample

Effect of increasing sampling resolution
-more bits per sample
-more amplitudes can be represented
-file size increases
-digital waveform is closer to original (accuracy)
-smaller quantisation errors

Question 16

Analogue data

Answer 16

A variable, data value that is constantly changing

Question 16

Compression Reasons

Answer 16

-reduces file size and takes up less space in memory (more space for other files)
-faster upload downdload rate, reduced transmission time for from/to web
-less badwidth used to transmit
-orginal may be too large to send via email attachment

Question 17

Lossy Compression

Answer 17

-orginal data lost and cannot be reconstructed (cannot be done in text file)
-if used in text file it would corrupt (all data required otherwise no sense would be made)
-videos have lower resolution will buffer less if being streamed real time, lowers bandwidth required to transmit
-used when all data is not required, quality can be reduced without user noticing, or if a significant reduction in file size is needed

Question 17

Lossless compression

Answer 17

-Original data is preserved
-Used when all data is needed, file needs to be fully restored, a high quality video/image needed, or it is already a relatively small size

Question 18

Compressing sound files

Answer 18

-reduces amplitude range to only range thta is used (reduces bits needed to store each ample)
-RLE, consecutive sounds group (binary value of sound recorded with amount of time it has been repeated)
-record only change sin sound, not actual sound

Question 19

Compressing Image files

Answer 19

Lossy
–reducing bit depth, reduces number of bits used to store each color (each pixel has fewer bit)
-reduce number of colors (reduces number of bits needed to store each color)
-reduce resolution-fewer pixel all togather(less binary to store)

Lossless
-RLE replaces sequences of same color pixels, with color code and number of identical pixels

Question 20

RLE

Answer 20

-identifies sequences of repeated characters and replaces them with a copy of character and number of times it occured

RLE limitations
-works by storing a color and number of time sit occures consecutivelu, there may not be many sequences of the same color
-it would store each color and then count, which only adds to file size
-eg RBG would be R2 G1 B1