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(GCSE ARCHIVE) Computer Systems and Databases Flashcards

1
Q

What is hardware?

A

Hardware is the physical components that make up a computer system, such as a CPU and motherboard.

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2
Q

What is software?

A

Software is the programs that run on a computer.

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3
Q

What are the two types of software?

A
  • System software: Software that governs a computer system. Examples include operating systems, utilities).
  • Application software: Programs that help the user perform specific tasks. Examples include word processors, web browsers, games)
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4
Q

Computer systems can either be general purpose or dedicated systems. Explain what these mean. Give examples of both.

A
  • General purpose: Designed to perform many tasks. Examples include PCs and tablets.
  • Dedication systems: Designed for one particular function. Examples include controlling the function of a dishwasher.
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5
Q

What are embedded systems?

A

Computers built into other devices, like dishwashers, microwaves and TVs. They are usually dedicated systems.

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6
Q

What do embedded systems normally do?

What are the advantages of embedded systems?

A
  • Embedded systems are often used as control systems. They monitor and control machinery in order to achieve a desired result.
  • As they’re usually dedicated systems, and only serve one purpose, they are easier to design, cheaper to produce, and more efficient at doing their task than general purpose computers.
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7
Q

What is the CPU? What is a CPU’s processing power dependant on?

A
  • The Central Processing Unit. It is the brain of the computer, and processes all data and instructions.
  • A CPU’s processing power is dependant on many characteristics, such as clock speed, number of cores, cache size and type.
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8
Q

What are the 5 main part of a CPU?

A
  • The Control Unit (CU)
  • The Arithmetic Logic Unit (ALU)
  • Cache
  • The Clock
  • Buses
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9
Q

What is the control unit (CU)?
What is its main job?
What does it do?

A
  • The control unit controls the CPU.
  • Its main job is to manage the fetching, decoding, and execution of program instructions, by following the Fetch-Execute cycle.
  • It controls the flow of data inside the CPU and outside the CPU.
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10
Q

Arithmetic Logic Unit (ALU)

A
  • Does all the calculations in the CPU
  • It completes simple addition, subtraction, and compares the size of numbers. It can do multiplications and divisions by using repeated addition and subtraction.
  • It performs logic operations such as AND, OR, and NOT, and binary shifts.
  • Registers are used to store intermediate results of calculations.
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11
Q

What is cache? How expensive is it? What does it store? Where is it found, and how does this determine its speed?

A
  • Very fast memory in the CPU. Slower than registers, but faster than RAM.
  • Stores regularly used data so the CPU can access it quickly whenever it’s needed.
  • Caches have a very low capacity and are expensive compared to RAM and secondary storage.
  • Speed is based on distance from the CPU. Some cache is on the motherboard, some is directly on the CPU.
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12
Q

The Clock

A
  • The clock sends out a regular electronic pulses at a consistent rate, to synchronise all components in a CPU.
  • This pulse is used to synchronise when instructions will be carried out.
  • The number of clock cycles per second is called the clock speed.
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13
Q

What are buses, and what are there different buses for?

A
  • Buses are collections of wires that are used to transmit data between components of the CPU, and to other parts of the computer system.
  • A processor may have separate buses for carrying data, instructions, and memory addresses.
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14
Q

Registers

A
  • Small, high-speed storage locations that temporarily hold data and instructions.
  • Super-quick to read/write to, quicker than any other form of memory.
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15
Q

Describe the ‘Fetch’ of the FDE cycle

A

1) The control unit reads the memory address of the next CPU instruction.

2) The instruction stored in that address is copied from memory to one of the registers.

3) The memory address in the control unit is incremented to point to the address of the next instruction, ready for the next cycle.

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16
Q

Describe the ‘Decode’ of the FDE cycle

A

1) The instruction that was copied from the memory is decoded by the control unit.

2) The control unit prepares for the next step, e.g. by loading other values into the registers.

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17
Q

Describe the ‘Execute’ of the FDE cycle

A
  • The instruction is performed. This could be: Loading data from memory. writing data to memory, doing a calculation or logic operation, changing the address in the CU, or halting the operation.
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18
Q

4 different types of memory in a computer

A
  • Registers
  • Random Access Memory (RAM)
  • Cache
  • Read Only Memory (ROM)
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19
Q

Volatile memory

A

Storage (such as RAM) that is wiped clean of its data when power is cut off from a device.

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20
Q

Non-volatile memory

A

Memory that can retain the stored data even when not powered.

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21
Q

RAM (Random Access Memory)

A
  • Ram is used as the main memory in a computer.
  • It can be read and written to.
  • RAM is volatile memory.
  • All data, files, and programs are stored while they’re in use in RAM.
  • The operating system is copied from secondary storage to RAM when booting up.
  • RAM is slower than cache, but much faster than secondary storage.
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22
Q

ROM (Read Only Memory)

A
  • Contains all the instructions a computer needs to boot up. These instructions are called BIOS (Basic Input Output System).
  • You can still update BIOS instructions however.
  • Non volatile
  • Used as main memory
  • Can only be read, not written to.
  • ROM is written to only once during manufacturing, and is built into the motherboard.
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23
Q

RAM/ROM requirements on Embedded vs Non-Embedded Systems

A
  • Non-embedded systems require more RAM. They need to write data to main memory.
  • ROM is only used for BIOS, which doesn’t require much memory.
  • ROM and RAM are usually stored on the motherboard, away from the CPU.
  • Embedded systems usually have more ROM than RAM.
  • They don’t need to write data to memory.
  • They normally don’t have secondary storage, so ROM is used to store all programs.
  • ROM and RAM are stored on the same chip as the CPU, to save space and reduce cost.
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24
Q

Clock Speed

A
  • The number of instructions a single processor core can carry out per second. Most modern CPUs use GHz (Gigahertz) to measure clock speeds.
  • A clock speed of 1 GHz = 1 billion instructions processed per second.
  • Can be increased through overclocking to run at a higher clock speed. This can make CPUs overheat.
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25
Q

CPU cores

A
  • Each core in a CPU can process data independently of the rest.
  • The more cores a CPU has, the more instructions it can carry out at once, meaning it can process data faster.
  • Doubling cores doesn’t always mean double performance, as software has to be designed in order to talk advantage of the extra cores.
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26
Q

GPU’s (Graphics Processing Units)

A
  • GPUs handle graphics and image processing.
  • They relieve the processing load on the CPU.
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27
Q

What is Primary and Secondary storage? What are their differences?

A
  • Primary storage is memory areas that CPU can directly access, e.g. registers, cache, ROM and RAM.
  • Secondary storage is non-volatile storage that isn’t directly accessible by the CPU. All data (e.g. applications, user files, OS) is stored here when not in use. Examples include HDDs, SSDs, CDs, SD cards. Generally much slower than primary storage.
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28
Q

Magnetic Hard Disks (HDDs

A
  • HDDs are made of a stack of magnetised metal disks spinning between 5500 and 15000 rpm.
  • Data is stored magnetically in small areas called sectors.
  • Read/write heads on a moving arm are used to access sectors on the disks.
  • Portable HDDs are useful for backing/transporting large amounts of data.
  • HDDs are very reliable and long-lasting, despite their moving parts.
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29
Q

Magnetic Tape

A
  • Very high capacity type of magnetic storage.
  • Extremely low cost per GB.
  • Used by large organizations for backing up large amounts of data.
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30
Q

Solid State Drives (SSDs)

A
  • No moving parts, data is stored in electrical circuits by trapping electrons.
  • Significantly faster read/write times than HDD, resulting in a much faster PC boot time and opening times for programs and files.
  • Hybrid disks that use both HDD and SSD technology exist.
31
Q

Flash storage

A
  • A compact, portable storage device that uses special memory chips to store data.
  • USB pen drives and SD cards are other examples.
  • Used to expand the storage of small devices (such as smartphones) where SSDs/HDDs are too large.
32
Q

Advantages of HDDs

A
  • Cheaper than SSDs
  • Higher capacity than SSDs
  • Longer reader/write life than SSDs, as SSDs can only be written to a certain number of times before deteriorating.
33
Q

Advantages of SSDs

A
  • SSDs are faster than HDDs-
  • SSDs don’t need defragmenting
  • SSDs are more shock-proof than HDDs
  • They are silent, whereas HDDs make some noise
  • They are not disturbed by magnets.
34
Q

Optical Discs

A
  • Things like CDs, DVDs, and Blu-Ray discs.
  • CDs hold around 700mb, DVDs around 4.7gb, Blue-Rays around 25gb.
  • They come in 3 forms: Read-Only (CD-ROM, DVD-ROM, BD-ROM), Write-Once (CD-R, DVD-R, BD-R), and Rewritable (CD-RW, DVD-RW, BR-RW)
  • Declining in use as media content can be streamed online, and most new devices don’t have optical drives.
  • They are cheap (per GB), and water/shockproof. They are easily scratched however.
35
Q

Cloud Storage

A
  • Cloud storage is a service where files can be uploaded via the internet to a remote server, where data is then stored in large data farms of SSDs and HDDs.
  • You normally pay a subscription to access these services, although some provide limited cloud for free.
36
Q

Advantages of cloud storage

A
  • Files can be accessed from any device connected to the internet.
  • Files can be easily shared with others.
  • Easy to increase how much storage you have.
  • No need to buy expensive hardware to store data.
  • Can be cheap/free is not much storage is required.
37
Q

Disadvantages of cloud storage

A

-Need an internet connection to access files.

-Upload/download speed depends on bandwidth.

-Dependent on host for security and backups.

-Stored data is vulnerable to hackers.

-Unclear who has ownership over cloud storage.

-Subscription fees are expensive in the long run.

38
Q

Purposes of an operating system

A
  • Communicate with input/output devices via devices drivers.
  • Provide a platform for applications to run on, and a user interface.
  • Control memory management and allocation.
  • Organise the CPU and its processing tasks.
  • Manage system security and user accounts.
  • Deal with file management and disk management.
39
Q

I/O devices and Operating Systems

A
  • Every I/O device requires a device driver to be used. Drivers act as ‘translators’ for the signals between the OS and the device.
  • When a device is booted up, the OS chooses the correct drivers for each detected device.
  • Driver updates to fix bugs or add features can be installed automatically by the OS.
40
Q

Operating System’s User Interface (UI)

A
  • Most computers use GUIs (graphical user interfaces) that are WIMP based. (Windows, icons, menus, pointers).
  • These interfaces are ideal for mouse/keyboard input.
  • Devices with different input methods (e.g. touchscreen on tablet) have different interfaces.
  • Applications are written from a particular OS to take advantage of its features.
41
Q

How does the OS handle Memory Management?

A
  • When an application is opened, the OS copies all necessary parts to memory, and additional parts later when they are needed.
  • The OS decides if applications have been used recently. If not, they may be removed from memory.
  • The OS manages how much RAM a program is allocated. This depends on the program, e.g. image editing software needs more RAM than a word processor.
  • The OS makes sure multiple applications don’t overwrite or interfere with each other by allocating different applications certain memory addresses.
42
Q

How does the OS handle file and disk management?

A
  • File extensions (e.g. mp3 or mp4) tell computers which software should be used to open the file.
  • The OS organises data into usable hierarchical structure. It also deals with moving, editing, and deleting data.
  • The OS manages/maintains the hard disk with utility programs and defragmentation software.
  • The OS manages the hard disk, by splitting the physical device into storage sectors, and decides which sectors to write data to.
43
Q

How does the OS manage System Security

A
  • Each user has access to their own personal data and desktop, and cannot access other users’ personal data (unless they are system administrators).
  • Operating systems have anti-theft measures to prevent others from accessing locks devices or accounts. User accounts may be password, pin, pattern, or biometrically protected.
44
Q

What are utility programs? Give the 7 types of common utility programs on a computer.

A

Utility programs are programs that are used to maintain or configure a computer. Many useful utilities are installed with the operating system, but others can be installed later.

  • Defragmentation Software
  • Disk Health
  • System Clean-up
  • Compression
  • Backup
  • Encryption
  • Virus Scanners
45
Q

Defragmentation Utility Software

A
  • Files are stored on a hard disks in available spaces. As files are moved and deleted, gaps appear on the disk.
  • The OS has to split new files up to fill up these gaps. This makes reading these files slower as the read/write head has to move back and forth across the disk.
  • Defragmentation software places all related files together (e.g. files for the same game), so that they can be accessed quicker.
46
Q

Disk Health Utility Software

A

Over time, hard drives can start to deteriorate, causing corrupted data and slow read/write speeds. Disk health utilities scan the drive for problems and fix issues where possible.

47
Q

System Cleanup Utility Software

A

Programs like web browsers leave lots of temporary files on your hard drive. These files end up unnecessarily taking up lots of space, so system clean-up utilities go through hard drives and get rid of these files.

48
Q

Compression Utility Software

A

Compression software reduces the size of files so they take up less disk space. This is used on the internet alot to make files quicker too download.

49
Q

Backup Utility Software

A
  • A backup is a copy of a computer system’s files and settings that is stored externally. Backups are used to restore data in the event of data loss.
  • Data loss can occur for many reasons, such as, fire, theft, water damage, malware, hardware failure, or accidentally deleting files.
50
Q

Encryption Utility Software

A

Encryption software encrypts (scrambles) data to stop third-parties from accessing it. Encrypted data can be decrypted using a special ‘decryption key’.

51
Q

Virus Scanners Utility Software

A

Virus Scanners inspect each file on a computer, looking for viruses. They usually have a list of viruses to check for, and so they need to be updated regularly to add any new viruses.

52
Q

High-Level languages

A
  • Source code is easy for humans to understand and write.
  • One instruction of high-level code represents many instructions of machine code.
  • The same code will work for many different machines and processors.
  • The programmer can easily store data in many different structures (e.g. lists, arrays) without knowing about the memory structure.
  • Must be translated before a computer can understand it.
  • You don’t have much control over what the CPU does, so programs are less memory efficient and slower.
53
Q

Low-level languages

A
  • You can control exactly what the CPU does so programs can be more memory efficient and faster.
  • Usually written for one type of machine/processor and won’t work on any others.
  • The programmer needs to know about the internal structure of the CPU.
  • Code is very difficult for humans to read, understand, and modify.
54
Q

How do computers understand instructions and code?

A

Computers do not understand any high-level or assembly languages that we humans mostly use. All code must be translated into machine code to be understood.

55
Q

What are the three types of translators?

A
  • Assemblers translate assembly language into machine code. Each type of assembly code needs its own unique assembler.
  • Compilers translate all high-level code directly into machine code, and create an executable file.
  • Interpreters don’t translate directly into machine code. Instead, they take each instruction in the code, line by line, and call machine code subroutines within their own code to carry out that instruction.
56
Q

Compilers

A
  • Translates all of the source code at the same time, and creates an executable file.
  • Only needed once to create the executable file.
  • Returns a list of errors for the entire program once compiling is complete.
  • Once compiled the program can run quickly, but compiling can take a long time.
  • Data must be recompiled every time a program is updated.
57
Q

Interpreters

A
  • Translates and runs the source code one instruction at a time, and doesn’t create an executable file.
  • Needed every time you want to run the program.
  • The interpreter will stop as soon as it encounters an error, and return the error. It is more useful for debugging.
  • Programs will run more slowly because the code is being translated as the program is running.
58
Q

Databases. Explain what these are:

  • Columns
  • Rows
  • Primary Key
A
  • Columns of data are called fields.
  • Rows of data are called records.

Each field has a specific datatype assigned to it (e.g. Age would be an integer)

  • Each table has primary key. A primary key is a field which can uniquely identify any record in the table. There is only one primary key per table.
59
Q

Flat-file databases

A
  • A database that stores all data in just one table.
  • Easy to set-up and understand.
60
Q

Relational Databases

A

Databases that store all data in multiple tables, which are linked together using primary & foreign keys.

61
Q

What is a foreign key?

A

A foreign key is a field in a table that references the primary key of another table, creating a link between two tables.

62
Q

Advantages of relational databases

A
  • Only storing a piece of data once saves storage space.
  • They are more secure, as some tables in a databases can be made confidential, so users can only access certain data.
  • Data is stored in one place then referenced elsewhere. Inputting, updating, or deleting data only h as to be done in one place, which can prevent inconsistencies.
63
Q

Data redundancy

A

Data redundancy is when the same piece of data is stored in multiple places. It can cause big problems for large databases.

64
Q

How to use the ‘SELECT’ and ‘FROM’ keywords to retrieve columns you want to return and choose the table used.

A

SELECT enter fields, separated with comma

FROM name of table

Example:

SELECT room1, room2, room3

FROM hotels

This will return the columns room1, room2, and room3

65
Q

Wildcard *

A

A character that returns all fields in a database.

66
Q

How to use ‘WHERE’ keyboard to specify conditions needed for a record to be returned.

A

WHERE your condition

Example:

SELECT * FROM hotels WHERE hotelrating >= 4.5

Example with Boolean operators:

SELECT * FROM hotels WHERE hotelrating >= 4.5 AND price < 50

67
Q

How to use the ‘ORDER BY’ keyword to order data before it’s returned.

A

ORDER BY field name ASC/DESC

Example:

ORDER BY price DESC

68
Q

How do ASC and DESC work?

A

ASC - Low to High

DESC - High to Low

69
Q

How to use the ‘INSERT INTO’ and ‘VALUES’ keyword to add a new record.

A

INSERT INTO table VALUES

(6, Marriot Hotel, 4.8, Ensuite, 50)

Example:

INSERT INTO hotels VALUES

(6, Marriot Hotel, 4.8, Ensuite, 50)

This will add an entire record.

70
Q

How to use the ‘INSERT INTO’ and ‘VALUES’ keyword to only add data to certain fields.

A

INSERT INTO table (*specify fields, separated by comma)

VALUES (6, Marriot Hotel, 4.8, Ensuite, 50)

Example:

INSET INTO hotels (ID, name, rating)

VALUES (7, Marriot, 4.5)

This will only add data into specific fields.

71
Q

How to use ‘UPDATE’, ‘SET’, and ‘WHERE’ to update records.

A

UPDATE table SET fieldname = value WHERE ID = 3

Example:

UPDATE hotels SET price = 21, rating = 3.5 WHERE ID = 3

72
Q

How to use ‘DELETE FROM’ and ‘WHERE’ to delete records.

A

DELETE FROM table WHERE field = value

Example:

DELETE FROM hotels WHERE rating = 2.3

73
Q

How to use primary and foreign keys to join two tables.

A

WHERE primarykey = foreignkey

EXAMPLE:

WHERE viewings.propertyNumber = customers.propertyNumber

74
Q

A database can form…

A

Reports - Data presented in a readable form.
Queries - Searches for specific information in a database.

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