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A Level Computer Science > Unit 1.1 - Characteristics of contemporary processors, input, output and storage devices > Flashcards

Unit 1.1 - Characteristics of contemporary processors, input, output and storage devices Flashcards

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1
Q

What is the Control Unit (CU)?

A

Coordinates all activities of the CPU and directs the flow of data between the CPU and other devices. ​

It, with the help of the DU, decodes the instruction currently being executed.

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2
Q

What is the Program Counter (PC)?

A

Holds the address of the next instruction to be executed.​

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3
Q

What is the Memory Address Register (MAR)?

A

Holds the address of the memory location from which data or an instruction is to fetched or to be written.​

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4
Q

What is the Memory Data Register (MDR)

A

Used to temporarily store the data which is read from or written to memory.

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5
Q

What is the Current Instruction Register?

A

Holds the current instruction being executed, the contents of the MDR are copied to the CIR if it is an instruction.​

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6
Q

What is the Arithmetic Logic Unit?

A

Performs arithmetic, logical and boolean operations on data.​

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7
Q

What is the accumulator?

A

The result of calculations carried out by the ALU can be temporarily stored here.​

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8
Q

What are the three buses called?

A
  • Data Bus
  • Address Bus
  • Control Bus
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9
Q

What is the Decode Unit (DU)?

A

Works with the CU to translate the instruction and fetch register operands using the register set identifier.

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10
Q

What is the Data Bus?

A

Carries the binary 1s and 0s that make up the actual information being transmitted around the CPU/Computer.​

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11
Q

What is the Address Bus?

A

Carries memory addresses that identify where the data is being read from or written to.​

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12
Q

What is the Control Bus?

A

Carries command and control signals to and from every other component of the CPU/Computer.​

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13
Q

What is assembly code?

A

A language that has a direct one-to-one relationship with the processor architecture.​

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14
Q

What is the Little Man Computer?

A
  • An instructional model of a computer, created around 1965. - It models a simple Von Neumann architecture.
  • Can be programmed using machine code (normally binary numbers that represent instructions to the computer).
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15
Q

What is the OPCODE?

A

The bit field identifying the instruction.

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16
Q

What is the OPERAND?

A

The bit field identifying data locations.

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17
Q

What is the Clock speed?

A

Number of cycles per second, measured in hertz (Hz)​

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18
Q

What is the Cache?

A

Temporary storage of data and instructions being read to and written from, located on or near the CPU.​

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19
Q

What is a Core?

A

A complete copy of the CPU.

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20
Q

What is Pipelining?

A

The process of fetching one instruction while executing another, which enables higher throughput of instructions in the CPU.​

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21
Q

What is a RISC processor and what does it do?

A

A microprocessor that aims to use simple instructions that will be executed within a single machine/clock cycle.​

Executes smaller number of simple, standardized instructions that are all a fixed length.

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22
Q

What is a CISC processor and what does it do?

A

A microprocessor that completes a task in as few lines of assembly as possible.​

Executes a large number of complex instructions at variable length.

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23
Q

What is a GPU and what does it stand for?

A
  • Graphical Processing Unit
  • A co-processor initially used for rendering graphics.​
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24
Q

What is Parallel Processing?

A

The processing of program instructions by dividing them between multiple processors or processor cores.​

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25
Q

What is an Input device?

A

Any device that allows you to pass information from the outside world into a computer system.​

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26
Q

What is Optical Storage?

A

Written and read using lasers, they spin so the laser can read the (indentations) data from the correct location.​

The surface of the disk will have billions of locations where holes can be physically burned by a laser or not to represent “1” or “0”.

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27
Q

What is an Output device?

A

Any device that can take data stored in digital form and convert it into another format that humans can process.​

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28
Q

What is Magnetic Storage?

A

Divided into tracks and sectors. Tracks are circular in shape and each track is divided into eight segments.

The disk spins so the disk’s read-write head can access the data in a segment.​

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29
Q

What is Solid State Storage?

A

They use flash memory to store data and use a special type of memory that can retain its state once power has been disconnected.​

This is called EEPROM.

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30
Q

What is RAM, and what does it stand for?

A
  • Random Access Memory
  • Temporary storage of instructions and data that is being executed by the processor
  • Volatile memory
  • Much faster than hard disk
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31
Q

What is ROM and what does it stand for?

A
  • Read Only Memory
  • Located on the motherboard
  • Non-volatile
  • Contains the BIOS - very first instructions for the computer (bootstrap).​
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32
Q

What do these mnemonics mean?

  1. ADD
  2. SUB
  3. STA
  4. LDA
A
  1. Add
  2. Subtract
  3. Store
  4. Load
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33
Q

What are the factors that affect the performance of the CPU?

A

• The number of cores
• The Size of the registers
• The clock speed
• The speed of the RAM
• The speed and width of the data bus
• Size of the cache

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34
Q

What do these mnemonics mean?

  1. BRA
  2. BRZ
  3. BRP
A
  1. Branch Always
  2. Branch if zero
  3. Branch if positive
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35
Q

What do these mnemonics mean?

  1. INP
  2. OUT
  3. HLT
  4. DAT
A
  1. Input
  2. Output
  3. End program
  4. Data location
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36
Q

Why is pipelining important for efficiency?

A
  • Allows different parts of instructions across different stages to be completed in different registers at the same time.
  • Reduces the processor’s cycle time as it can process more instructions simultaneously, while reducing the delay between completed instructions.
  • The CPU does not have to wait for one instruction to complete the machine cycle.
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37
Q

What are the disadvantages of pipelining?

A
  • Designing of the pipelined processor is complex.
  • Instruction latency increases (timing variations)
  • Difficulty of Parallelization
  • Branch instructions may not benefit
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38
Q

What are the advantages of pipelining?

A
  • Faster Processing
  • Improved Resource Utilization
  • Flexibility
  • Lower Latency of entire workload.
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39
Q

What are the two old computer architectures?

A
  • Von Neumann architecture
  • Harvard architecture
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40
Q

What are the features of the Von Neumann architecture?

A
  • Shared memory space for instructions and data
  • Instructions and data are stored in the same format
  • A single CU follows a linear F-D-E cycle (one instruction at a time)
  • Registers used as fast access to instructions and data
  • More than a single clock cycle may be required to execute a single instruction.
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41
Q

What are the features of the Harvard architecture?

A
  • Instructions and data are stored in separate memory units
  • Each memory unit has its own system bus
  • Reading and writing can be done at the same time as fetching an instruction
  • Used by RISC processors
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42
Q

What does SIMD stand for?

A

Single Instruction Multiple Data

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43
Q

What does MIMD stand for?

A

Multiple Instruction Multiple Data

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44
Q

What is distributed computing?

A
  • When multiple computers on a shared network take part on a bigger problem which can be done over a grand scale over the Internet.
  • Done by designing the software so different computers can program different functions and communicate to develop the final solution.
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45
Q

What is SIMD?

A
  • Takes an operation in a single instruction and applies it to multiple sets of data elements at the same time.
  • Used in graphics cards and multimedia processing (e.g. filling a shape red in Paint).
46
Q

What is MIMD?

A
  • A parallel architecture, where multiple cores operate independently and asynchronously.
  • Various processors may be carrying multiple instructions at the same time on different data items.
47
Q

What is an instruction set?

A

A set of all instructions written in machine code that can be recognised and executed by a given processing unit/CPU.​

48
Q

What are the two types of instruction set architectures in processors?

A

CISC and RISC

49
Q

What does CISC stand for?

A

Complex Instruction Set Computer

50
Q

What does RISC stand for?

A

Reduced Instruction Set Computer

51
Q

What are advantages of RISC processors?

A
  • Supports pipelining
  • Simpler hardware
  • Smaller in size, less complex circuitry, less silicone to make, typically cheaper to produce
  • Lower energy requirements
52
Q

What are disadvantages of RISC processors?

A
  • Heavy use of RAM (can cause bottlenecks if RAM is limited)
  • Fewer addressing modes available and fixed format (due to simplistic design)
  • Larger code sizes, lower cycles per second.
  • Emphasis is on software (causing heavy use in RAM), so compiler has to do more work
53
Q

What are advantages of CISC processors?

A
  • More emphasis on hardware, so less on software
  • Multiple machine/clock cycles per instruction
  • Small code sizes, higher cycles per second
  • More efficient use of RAM than RISC
  • Multiple address modes available and variable format for instructions in CIR (depending on the command being decoded)
54
Q

What are disadvantages of CISC processors?

A
  • More complex hardware
  • Physically larger, more complex circuitry, more silicone to make, more expensive
  • Greater energy consumption
  • Can’t make use of pipelining
55
Q

What are RISC processors used in?

A
  • Smartphones
  • Tablets
  • Embedded systems
    (made popular by ARM processors)
56
Q

What are CISC processors used in?

A
  • Laptops
  • Desktop computers
    (x86 processors made mainly by Intel and AMD)
57
Q

What is a co-processor?

A

An additional processor used for a specialised task.

It can improve the computer’s performance by executing concurrently with the CPU.

58
Q

What are the other purposes of a GPU other than rendering graphics?

A
  • Cryptocurrency
  • AI
  • Weather modelling
  • Statistical analysis
  • Linear algebra
  • High Performance Computing
59
Q

Why were GPUs created?

A
  • Systems had a single CPU for carrying out all instructions so they were in high demand as tech advanced.
  • They were developed as cheaper alternatives of CPU for graphics.
60
Q

Why are GPU’s used for rendering graphics?

A
  • Rendering images would take numerous steps and mass calculations.
  • A huge number of these can be executed in parallel because they aren’t dependent on one another.
  • They can operate single instructions on multiple data sets at the same time (SIMD).
    ​
61
Q

How is a GPU different from a CPU?

A
  • CPU excels at performing complex operations on small data sets / GPU better suited for simple operations on large data sets.
  • CPU is a general processor / GPU supports CPU to perform concurrent calculations with built in circuitry/instructions.
  • CPU can process a single instruction faster than GPU / GPU can process numerous data in parallel (quicker than CPU). ​​
62
Q

What is a multi-core system?

A

An integrated circuit that has two or more processor cores attached for enhanced performance and reduced power consumption.

63
Q

What is a multicore processor?

A

A single chip containing two or more independent processing units which can independently process instructions at the same time.

64
Q

What does CMP stand for?

A

Chip Multiprocessor

65
Q

What is a CMP?

A

A physical chip integrated with multicore processors.

66
Q

What factors affect the performance of multicore processors?

A
  • On-chip shared cache
  • Inter-core communication
67
Q

What does it mean by “On-chip shared cache”

A

The cache is integrated onto the same chip (the same piece of silicon) as the CPU and its peripherals.

CPUs are connected to memory through a layered cache structure.
Each CPU has its own cache (L1 and L2) then several CPUs are grouped together on a chip, and they share a cache at this level (L3).

68
Q

What is inter-core communication?

A

The exchange of information among central processing unit (CPU) cores in a multi-core device.

69
Q

How does inter-core communication affect the performance of multicore system architecture?

A
  • Tasks on different processors require information exchange.
  • More intercommunication achieves a lower latency with reduced power consumption.
  • This improves the speed and efficiency of the whole system.
70
Q

How does on-chip shared cache affect the performance of multicore processor architecture?

A
  • Reduces cacheunderutilization
  • Offers quicker data transfers between the cores.
  • One core and pre/post process data for the other core (e.g. pipelining).
  • Provides better performance than just with a dedicated cache.
71
Q

What incidents mean that doubling the number of cores doesn’t double the performance?

A
  • Overheads involved with inter-core communication.​
  • Some programs can’t make maximum use of all cores.​
72
Q

What is the extent of which parallel processing can speed up computation highly dependent on?

A
  • The task being carried out (if an instruction needs data from the instruction after it)
  • If the software has been – or even can be – designed and written to make use of parallel processing.​

​

73
Q

What is a storage device?

A

Any device used for either temporary or permanent storage - it can be internal or external.

74
Q

What is a scanner?

A

When an image is digitised, it is converted into a series of pixels.

The pixels are stored as binary data based on the colour of the pixels.

75
Q

What is Optical Mark Recognition (OCR)?

A

It converts printed media into editable text using a scanner.

It performs pattern matching - it compares binary data to an internal database of known character shapes.

76
Q

What is Magnetic Ink Recognition (MICR)?

A

A combination of ink containing iron peroxide and specific fonts. Specialist ink can be read through normal ink.

77
Q

What is a barcode?

A

They allow devices reading them to back up data about a product to a database by using a laser to measure the reflective properties.

Different values are represented by the different thicknesses of lines. And there are terminators at the start and end of them.

78
Q

What is an actuator?

A

A part of a device / machine that enables movement by using a form of power to convert a control signal into mechanical motion.

79
Q

What is a sensor?

A

A device that detects and responds to some type of input from the physical environment.

80
Q

How do sensors and actuators work together?

A

Data recorded by a sensor is converted from analogue to digital and then processed. This usually causes some kind of output in the form of physical motion - which is caused by an actuator.

81
Q

What are the two types of touchscreen technology?

A
  • Resistive
  • Capacitive
82
Q

What is a touchscreen?

A

A display device that allows users to interact with a computer using their fingers or a stylus.

83
Q

What is a storage drive?

A

The device that reads and writes data from secondary storage.

84
Q

What is storage media?

A

What the data is actually stored on.

85
Q

What are the three types of secondary storage?

A
  • Optical
  • Magnetic
  • Solid state
86
Q

What does EEPROM stand for?

A

Electronic Erasable Programmable Read-Only Memory

87
Q

What are the advantages of solid state storage?

A
  • Better performance (no physical motion)
  • Fast access times
  • Durable/robust
  • Small and lightweight = portable
88
Q

What are the disadvantages of solid state storage?

A
  • Limited read/writes
  • Medium capacity
  • Expensive per GB
89
Q

What are the advantages of magnetic storage?

A
  • Cheap per GB
  • Large capacity
90
Q

What are the disadvantages of magnetic storage?

A
  • Slow access times
  • Fragile
  • Not portable
91
Q

What are the advantages of optical storage?

A
  • Cheap
  • Lightweight
  • Portable
92
Q

What are the disadvantages of optical storage?

A
  • Prone to scratches
  • Slow access times
  • Low capacity
93
Q

What is virtual storage?

A

The concept of storing and retrieving data over the internet in the cloud instead of a local storage device.​

94
Q

What is concurrent processing?

A

The process of completing more than one task at any given time.

Tasks are given parts of processor time, to give the illusion that tasks are being performed simultaneously

95
Q

What are the benefits of concurrent processing?

A
  • Resource utilization
  • The number of tasks completed in a given time is increased.
  • Less time is wasted waiting for an input or user interaction, as other tasks can be
    completed.
96
Q

What are the drawbacks of concurrent processing?

A
  • It can take longer to complete when large numbers of users or tasks are involved as processes cannot be completed at once.
  • There is an overhead in coordinating and switching between processes, which
    reduces program throughput.
  • Just as with parallel processing, not all tasks are suited to being broken up and
    performed concurrently.
97
Q

How are RAM and ROM similar?

A

They are both examples of solid state, allowing faster access to the data and speeding the computer.

98
Q

What are the four types of ROM?

A
  • ROM
  • PROM
  • EPROM
  • EEPROM
99
Q

What are the differences between RAM and ROM?

A
  • RAM has a higher storage capacity (GB) than ROM (MB)
  • RAM is volatile and ROM is non-volatile
  • RAM stores current instructions and data and ROM stores the BIOS.
100
Q

How is ROM used in embedded systems?

A

ROM is used to store an embedded operating system when the machine is off.

101
Q

How is RAM and ROM used to get ready to load the OS when the computer turns on?

A
  1. Power is turned on, and only ROM data can be accessed.
  2. POST is run and checks that all required components are present and available.
  3. Clears any data in CPU registers and increments the Program Counter.
  4. Bootstrap in ROM carries out checks on hardware
  5. BIOS is checked in ROM or CMOS RAM and combined with basic BIOS on ROM and sends it to RAM (the boot file).
  6. The computer is ready to load the OS.
102
Q

What is the BIOS?

A
  • Basic Input/Output System
  • A computer program (typically stored in EPROM) used to perform start-up procedures when the computer is turned on.
  • Determines what peripheral devices are available and loading the operating system (OS) into main memory.
103
Q

What is virtual storage?

A

The concept of storing and retrieving data over the internet in the cloud and the data being held in remote servers instead of a local storage device.

104
Q

What are the advantages of virtual storage?

A
  • Data can be accessed at any time from any device as long as there is an internet connection.
  • Data can easily be shared without the need for removable media transfer (e.g., USB drive).​
  • Easily to collaborate.​
  • Storage considered to be “limitless” from the user’s point of view. (very high storage capacity)
  • Automatic backups provided by hosts.
  • Version history and archiving of deleted files.
105
Q

What are the disadvantages of virtual storage?

A
  • Internet connection is required.
  • Poor internet connection means slower or no access.
  • Trusting third parties to back up data and keep it secure and not to resell your data (and they may not follow the Data Protection Act so cannot be tried)​
  • Can be very expensive (subscriptions), so must choose to pay up or loose data - monthly fee for large data capacities
  • Malware may spread through files
106
Q

What is logical storage?

A

The abstract view of the data that hides the details of its physical location and format.

The files on the local computer is a logical abstraction - it seems that those files are stored on the local computer but actually aren’t.

107
Q

What is physical storage?

A

The actual space of the hardware that is used to store the data on (e.g. a data centre such as Amazon or Google).

108
Q

Are files actually saved on a computer?

A
  • Files and folders appear to be stored on the computer but are actually not.
  • They instead exist in the cloud, and can be accessed via a network (usually the internet).
  • The files are actually held on remote servers at data centers (e.g. Google or Amazon).
109
Q

What happens when the OS is ready to load?

A
  • OS is normally found on the hard disk, but BIOS can be changed to check other drives first.
  • OS searches for files (e.g. CONFIG.SYS) - tells it how many files can be opened at once and which device drivers to load.
  • The OS takes control of the computer and memory and loads jobs into memory for processing.
110
Q

What are the characteristics of EEPROM?

A
  • The chip does not have to be removed to be rewritten.​​
  • The entire chip does not need to be completely erased to change a specific portion of it.​​
  • Changing contents does not require specialist equipment.​​
111
Q

What are the characteristics of ROM (with unchangeable data)?

A
  • Programming of data must be complete when the chip is created.​​
  • Cannot be reprogrammed or rewritten.​​
112
Q

What does volatile mean?

A

The data is lost when the power is turned off.

A Level Computer Science (13 decks)

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