Memory & Data Storage

Question 1

MIDI

Answer 1

Musical Instrument Digital Interface
Standard adopted by the music industry for controlling devices such as synthesizers and sound cards and electronic instruments.
Stores commands on how to play sounds – NOT SOUNDS

Question 2

Mp3

Answer 2

File compression system for music which does not noticeably affect the quality of the sound
Removes sound humans can’t hear well
If two sounds playing at the same time the softer sound is removed
Uses perceptual music shaping

Question 3

Differences between MP3 and MIDI

Answer 3

MP3 a digital recording of sound
Mp3 produced by recording software
Mp3 a compressed file format
MIDI Instructions of how to make sound
MIDI Non-audio recording
MIDI File created using digital musical instruments
MIDI Produced by synthesizer

Question 4

Image Capture

Answer 4

Image converted from analogue to digital (ADC)
Image turned into pixels
Each pixel given binary value
Each pixel given a colour
Pixels form a grid
Pixels stored in sequence

Question 5

File Compression

Answer 5

Can be lossless or lossy

Uses a compression algorithm

Question 6

Advantages of Compression

Answer 6

Smaller file to transmit
File transmitted quicker
Uses less bandwidth

Question 7

Lossless

Answer 7

Code must be exactly the same as the original
If not the same as original file will not work
A (compression) algorithm is used
No data is removed in the process
Used for Programs & Text Files
Repeated words (are identified) and are replaced by an index
The number of times the word appears is stored

Question 8

Lossy

Answer 8

E.g. Video file (Mpeg)
Makes the file smaller than lossless
Quality can be reduced but the file will still run
Redundant data can be removed
Used when no requirement for file to be exactly same as original

Question 9

Text File Compression

Answer 9

Use lossless
Repeated words can be indexed
Repeated words sections e.g. ‘ou’ can be replaced with numerical value
Can be saved a s a zip file

Question 10

Primary

Answer 10

RAM (Random Access Memory)

ROM (BIOS)

Question 11

DRAM

Answer 11

1. Tiny capacitors that leak electricity
2. Requires a recharge every few milliseconds
3. Inexpensive
4. Slower than SRAM
5. Can store many bits per chip
6. Uses less power
7. Generates less heat
8. Used for main memory

Question 12

SRAM

Answer 12

1. Circuits similar to D flip flops
2. Holds content as long as power is available
3. Expensive
4. Faster than DRAM
5. Cannot store many bits per chip
6. Uses more power
7. Generates more heat
8. Used for cache

Question 13

ROM (BIOS)

Answer 13

Non-volatile memory chip
Primary memory
In a microprocessor holds the BIOS
Can’t be written to

Question 14

PROM (Programmable read-only memory)

Answer 14

It can be programmed by user. Once programmed, the data and instructions in it cannot be changed.

Question 15

PROM (Erasable Programmable read only memory)

Answer 15

It can be reprogrammed. To erase data from it, expose it to ultra violet light. To reprogram it, erase all the previous data.

Question 16

EEPROM (Electrically erasable programmable read only memory)

Answer 16

The data can be erased by applying an electric field, with no need for ultraviolet light. Erase only portions of the chip.

NAND chips
More expensive
Faster read
Erase byte

Question 17

CACHE

Answer 17

Cache holds the information from the RAM that is most actively used, and accessed most frequently.
The computer system will run faster as the slower main memory will need to be accessed less frequently.
When the processor needs to read from the main memory, it first checks if a copy of the data exists in the cache.
If the data to be read do not exist in the cache, the data are first copied to the cache and then used.
When the processor needs to write to the main memory it does so through cache memory.

Question 18

HDD (hard disk drive)

Answer 18

Uses platters
Platters divided into tracks
Platter is spun
Read write arm moves over platter
Magnetic fields control magnetic dots of data
Magnetic field determine binary value

Question 19

SSD (solid-state drive)

Answer 19

Non-volatile memory

Uses NAND flash memory

Question 20

Why SSD replacing HDD

Answer 20

No moving parts (more reliable in a portable device)
Use less power
Smaller (good for portable devices)
Faster data access
Run cooler
Run quieter

Question 21

Why HDD still used in web servers

Answer 21

Cheaper for large amounts of data
Greater longevity for read/write functions
Don’t need faster speed of SSD
Expensive to change technology

Question 22

Off-Line Storage

Answer 22

Not directly accessed by CPU
Non volatile
Can easily be disconnected

Question 23

DVD

Answer 23

Uses 1 spiral
Red laser used to read/write
Dual layer technology

Question 24

DVD-RAM

Answer 24

Uses concentric tracks

Allows read/write operations at same time

Question 25

DVD-R Vs DVDRAM

Answer 25

DVD-R one spiral track DVD-RAM several concentric tracks
DVD-RAM can be written to and read at same time; DVD only allows read
DVD-R only allows read; DVD-RAM allows read and write
DVD-RAM can have direct access because of concentric tracks

Question 26

Blue-Ray

Answer 26

Uses blue laser

Uses single1.1mm polycarbonate disc

Question 27

Tape v SSD in Server

Answer 27

Greater longevity – more read and writes
Speed is sufficient
Cheaper per unit of data – better value
No portability requirement
Trusted technology

Question 28

How SSD works

Answer 28

Flash memory
Uses transistors
can be NAND/NOR tech
When stored in transistor data is converted from 1 to 0, 0 to 1
Controls the flow of electrons using transistors.
Stores data by flashing onto silicone chips
EEPROM tech

Question 29

How USB works

Answer 29

EEPROM tech
Uses transistors
When data is stored on transistors data is converted from 1 to 0, 0 to 1
Transistors control the flow of electrons.
flashed onto silicon chips
read and write simulationously

Question 30

TLS vs SSL

Answer 30

TLS makes use of session caching
TLS separates handshake and records
Possible to add new authentication methods