1.1.3 Input, output and storage devices Flashcards
1
Q
What is a Scanner
A
- It is an input device
- When a printed image or media is digitised, it is converted into a series of pixels. Generates a bitmap image.
- The pixels are stored as binary data on the colour of the pixel
2
Q
What is Optical Character Recognition (OCR)
A
- OCR converts printed media into editable searchable text using a scanner.
- Allows user to change sections of text and publish into new formats.
- It performs pattern matching
- This is done by comparing binary data to an internal database of known character shapes
3
Q
What is an Optical Mark Recognition (OMR)
A
- OMR is based on a predefined form
- The form has specific parts for someone to fill in
- A special reader then scans the form in order to detect dark marks and note their position. The scanner knows what option has been selected.
- (Used in human marked-data/ multiple choice Qs)
4
Q
What is Magnetic Ink Recognition?
A
- Combination of ink containing iron oxide and specific fonts. Can be read by MICR reader.
- This ink can be read through normal ink
- Allows the computer to read the characters on a check even if covered with signatures, bank stamps etc
5
Q
What are Barcodes?
A
- Barcodes allow devices reading them to look up data about a product in a database
- Different values are represented by different thickness of lines
- A reader uses a laser and measures the reflective properties
6
Q
How is a check digit (validation of barcodes) calculated
A
- Multiply value of each position. N1 x3, N2 x1, N3 X3 …. (find sum of all even digits, multiply odd position by 3 and add together)
- Add results together to create sum
- Subtract the sum from nearest equal or higher multiple of ten = check digit
7
Q
What are Sensors and Actuators
A
- Sensors read data from the physical environment e.g Pressure/ light/infrared.
- Data recorded by a sensor must be converted from analogue to digital then processed
- The processing will usually cause an output
- An output could be a physical motion
- An actuator is an output device which can cause a physical motion (e.g conveyor belts
8
Q
What are the 2 types of touchscreen
A
- Resistive - cheaper/ made of 2 thin transparent sheets. When they touch a voltage is recorded (position)
- Capacitive - sharper images. Multiple touchpoints touched simultaneously. Human body conducts electricity (changes electric field on area you touched)
9
Q
What is Secondary Storage
A
- A longer term of storage
- Types of secondary storage include memory sticks, floppy disk tapes and CDs
- Larger and cheaper
- Have lower access speeds
- Non-volatile and needs to be reliable and robust
10
Q
What do secondary storage devices usually store
A
- The OS and common utilities
- User applications
- User documents/files
11
Q
What are the 3 types of Storage devices
A
- Magnetic Storage Devices
- Optical Storage Devices
- Flash Storage Devices
12
Q
What is Magnetic Storage?
A
- Magnetic Storage devices include the internal hard drives and floppy disks
- These disks are divided into tracks and sectors
- Tracks are circular shape and each track is divided into 8 segments. Measured in RPM
- The disk spins so the read-write head can access the data in the segment
13
Q
What is Optical Storage
A
- Includes CDs, DVDs and Blu-Ray disks
- They are written and read using lasers.
- The disk spins so the laser can read from the correct location
- The surface of the disk will have billions of locations where holes are burnt/not with a laser this represents 0/1 - used to store binary data (pits and lands)
14
Q
What are Flash Storage Devices
A
- They use a special type of memory (EEPROM) which retains its state when power is disconnected
- Better performance, expensive, lower capacity.
- Performance = increase (no physical motion)
- Smaller (lightweight) and portable
- E.g Memory sticks and memory cards
15
Q
What is RAID
A
- Redundant Array of Independent/inexpensive discs
- RAID is a way of combining several independent and relatively small disks into a single storage of large size
- The disks included in the array are called array members
- The disks can combined in the array in different ways which are known as RAID levels
16
Q
What is RAID level 0 -striping
A
- RAID 0 = system data is split into blocks that get written across all the drives in the array
- Provides improved performance and additional storage
- However no fault tolerance = any errors can destroy RAID
17
Q
What is RAID level 1 - Mirrored
A
- Data is stored twice by writing them to both the data drives and a mirror drive. Each disc provides the same info
- If the drive fails, the controller uses either the data drive or the mirror drive for data recovery and continues operation
- However data is repeated, write speed is decreased. Read time increased.
- You need at least 2 arrays
18
Q
What is RAID level 3 and 4 - (Striped Parity)
A
- This level requires 3 disks in the array
- Provides fault tolerance/parity checks and error corrections
- The parity information is stored on a single drive, so other drives continue working when 1 fails
- The lost data can be calculated using parity data stored on the parity drive
- Parity data is additional data stored that is saved on each drive and on a parity drive
19
Q
What is SAN
A
- Storage Area Network
- SANs provide a greater degree of scalability than RAIDs
- A SAN will act as a gateway to a series of block devices such as RAIDs
- A SAN could be seen as a subnet of a network that is solely responsible for serving files
20
Q
What is Virtual Storage
A
- Virtual storage is storing information remotely so that it can be accessed by any computer with access to the same system.
- Google Drive and Microsoft OneDrive.
- As internet speeds increase, virtual storage is becoming a more popular due to the convenience
21
Q
What is RAM
A
- Random Access Memory
- It is used as main memory and acts as a temporary store for program instructions and data
- Volatile
- Can be accessed in any order (Random Access Memory)
- RAM holds billions of storage locations, each with its own memory address.
22
Q
What is ROM
A
- Read Only Memory
- Is a special memory which stores the instructions which a computer uses to boot up (BIOS) and stores essential systems software.
- It checks the type of hard disk installed, amount of RAM and type of CPU
- Non-volatile - comp needs instructions when it turns on/ needs info (configuration settings)
- Helps with start up and to run smoothly
23
Q
What are the differences between RAM and ROM
A
- RAM = volatile, ROM = non-volatile
- RAM = Read and Write, ROM = Read only
- RAM = Large Capacity, ROM = Smaller
- RAM = holds the programs when comp is running, ROM = Holds he first instruction when comp is is turned on
24
Q
What does the system software do
A
- Manage both software and hardware and is required to run any other type of software
25
What does Utility software do
* Used to support the OS and other software
26
What does Generic software do
* Software. e.g word processor, that can perform multiple tasks.
* Used to produce different types and styles
27
What does Bespoke Software do
* Specially built software for a specific purpose. Used to support businesses
* Will not be sold or used for other purposes than it was originally intended
28
What are the uses of barcodes
* Each barcode is unique and represents a specific set of data inside a database.
* Supermarket: info on price and stocks (can update values)
* Warehouses/delivery - keep track of deliveries
29
What are some disadvantages of virtual storage?
While virtual storage is convenient to access and share, its disadvantages include limitations of a user’s network speed and high costs.
30
Exam Question: The finance manager needs to work on some files at home and also to assess new software for use in the finance department. State three different storage devices that the finance manager would use and describe what each device would be used for.
Hard drive… …to store files and software
Memory stick / solid state device… …to allow transport of materials between office and home
Cloud storage… …to make files available to others in the dept / from anywhere / on any device
31
Exam Question: State the purpose of an input device in a computer system when using this software
State the purpose of an output device in a computer system when using this software
Allows data to be given / entered (into the computer)
Reports the results of processing (to the user )/ shows state of software (to user)
32
Exam Question: Explain two advantages of this monitoring system having its operating system stored in ROM.
* ROM is quick to start up so the system can be started up quickly (in an emergency) (1).
* ROM cannot be altered so there is no chance of the OS being accidentally or maliciously changed (on what is a safety critical system) (1)
33
Exam Question: State two differences between RAM and ROM in a typical PC computer system
* RAM is volatile / ROM is not volatile
* RAM is editable / ROM cannot be altered
* RAM is larger / ROM is smaller
34
Exam Question: Describe one advantage of the digital camera using flash storage rather than magnetic
* Has no moving parts… (1) … less likely to be damaged / data loss
* - Faster access speed… (1) - …so photographs can quickly be written to it / browsed
* - Consumes less power… (1) …meaning battery needs recharging less often
