Hardware Flashcards
What are input devices
Anything used to input into a computer
E.g. keyboard, mouse etc.
What is a processor (CPU)
The brain of the computer
Controls the transmission of data to and from main memory.
Processes the data in main memory
Controls the transfer of data between input, output and memory
What are output devices
Anything the user can see or hears will be done by an output device
E.g. a speaker, monitor etc.
What is RAM cache memory
A fast type of memory which sits on the processor
What is external backing store
A large storage device used to hold data when the computer is offline
E.g. hard disk
What is RAM
Random Access Memory
Used to store anything running on the computer at the current moment
What is ROM
Read Only Memory
Used to store small amounts of information used to boot up
Is RAM Volatile or Non-Volatile
RAM is Volatile (data is lost when power is removed)
What does RAM memory hold
Like all memory RAM can hold program instructions (e.g. a game) and data (e.g. a score in a game)
What happens to programs to be executed
They are first loaded from backing store (e.g. Hard disk) into RAM before being run
This is because RAM is much faster
Is ROM volatile or Non-Volatile
ROM is Non-Volatile (data remains when power is turned off)
How does a computer boot up?
ROM holds a simple operating system (BIOS) ‘burnt’ onto the chip at the time of manufacture
The BIOS runs a ‘bootstrap loader’ that looks for another operating system (e.g. Windows, Linux) to load into RAM from backing store
Name the different components of the CPU
Control unit
Arithmetic Logic Unit (ALU)
registers
Name all the special registers in the CPU
MAR (Memory Address Register)
MDR (Memory Data Register)
PC (program counter)
CIR (Current Instruction Register)
What is the instruction set
The commands available to the CPU
What is a Control Unit
A control unit fetches each instruction in sequence from memory, decodes and synchronises it before executing it by sending control signals to other parts of the computer
Arithmetic Logic Unit (ALU)
Carries out the processing and manipulation of data
Consists of arithmetic operations Or logical comparisons
What are registers
Temporary memory locations within the CPU
What does the MAR (Memory Address Register) do
Holds the address of the memory location currently being accessed
In the fde cycle it holds the address in main memory that is currently being read or written
What does the MDR (Memory Data Register) do
Holds data read from (or to be written to) memory
What does the CIR (Current Instruction Register) do
Stores the instruction most recently fetched from memory
What are buses
Collections of wires inside the CPU
They transmit information between the components and also to input/output devices
There are 3 different bus types
What is an Address bus
This is used to specify the address in memory where data will be read from or written to
What is a Data bus
Used to transfer data from memory into the CPU
Or from CPU back to memory
What is a control bus
Used to send control signals between parts of the computer
What does RAM cache memory attempt to solve?
It attempts to solve the von neumann bottleneck
This is where the processor runs much faster than the memory by acting as a middleman between main memory and the registers.
What are the properties of cache memory
Cache is small, extremely fast memory
Where is cache memory located
On or near the processor
What happens to data and instructions in cache memory
Data and instructions that are used regularly are stored in cache and retrieved by the processor when necessary
When the cache is full least recently used data is discarded
What is disk cache
Works similar to RAM cache as it keeps blocks of data in RAM so that recently accessed blocks can be read more quickly again from RAM rather than having to read from the slower hard disk
Name a problem with the von neumann architecture
The program instructions and data are accessed via the same data and address buses
Meaning that unstructured being fetched and data being accessed compete for the same resources
What is parallel processing
The use of more than one processor or processor core to perform a single task.
What is an advantage of parallel processing
It is useful where large/complex calculations are being carried out
E.g. image processing, weather forecasting
What is assembly language
A very low level language
Very close to machine code
Commands are very simple
Explain the fetch decode execute cycle
- The value in the PC is incremented by one
- The address value is then stored in the MAR
- The address is then sent from the MAR along the address bus to the main memory RAM
- The instruction at thst address is found and returned along the data bus to the MDR
- At the same time the PC increments by one
- The control unit then loads the CIR from the MDR with the instruction to be executed
- The instruction is then decoded and executed
What is speech recognition
Providing input into the computer via your voice
What is speech synthesis
The computer is outputting speech
What is handwriting recognition
When you write on a tablet and the computer will read what is being written
What are the advantages of speech recognition
- no need to type
- faster input
- very useful for some disabled people
- useful when hands are occupied
What are the disadvantages of speech recognition
Background noise can cause problems
Accents - may have to “learn”
May not recognise slang words
Colds, speech impediments etc.
What are the three types of speech recognition
Speech dictation
Command and control
Voice recognition
What does speech dictation do
Records every word
What does speech command and control do
Use your voice for commands to do certain things
What does voice recognition do
Measures the unique biological factors of your voice
Can then be used for authentication
What are the advantages of speech synthesis
Computer able to read documents/emails/ebooks
Useful for the partially sighted
Used to help people pronounce words
No need to look at screen, tells information when eyes are occupied (e.g. satnav)
What are the advantages of speech synthesis
Computer able to read documents/emails/ebooks
Useful for the partially sighted
Used to help people pronounce words
No need to look at screen, tells information when eyes are occupied (e.g. satnav)
What are the disadvantages of speech synthesis
Often quicker to read it yourself
Voice often sounds unnatural
What are the advantages of handwriting recognition
Many people can write faster than they can type
No need to learn a new skill to type
Useful when there is limited space
What are the disadvantages of handwriting recognition
Not always 100% accurate
Some handwriting is very difficult to interpret
Using the pen interface can feel unnatural
Name interfaces that can be used for people with disabilities
Speech recognition
Foot controlled keyboard/mouse
Oversized keyboard
Head/eye movement detector
Large/clear fonts
How is assembly language converted to machine code
Using an assembler
What is mechanical storage
Any storage that has moving parts involved e.g. HDD, CD-ROM
What are the disadvantages of Hard Disks
More likely to be damaged if dropped due to moving part
Will sometimes require defragmentation
What is an advantage of Hard Disks
They generally have a long life span
What are solid state drives
Direct replacements for hard drives
Has no moving parts
Disadvantages of SSD
Tend to be less reliable over time
Direct replacement for hard-drives
Use more expensive flash memory
Advantages of solid state drives
Made up of NAND flash which is shock resistant
No moving parts so tends to be more power efficient
Tend to be lighter, quieter and run cooler than traditional hard drives
What is a bit
A bit is a binary digit (0 or 1)
What is a byte
A byte is 8 bits
How big is a kilobyte (Kb)
1024 bytes
How big is a megabyte (Mb)
1024 Kb
How big is a gigabyte (Gb)
1024 Mb
How big is a terabyte (Tb)
1024Gb
What is word size
The number of bits that the processor can deal with in a single operation.
E.g. a 64 bit pc has a word size of 64 bits (8 bytes)
What is fragmentation
When a file system cannot or will not allocate enough contiguous space to store a complete file as a unit, but instead puts parts of it in gaps between existing files
Why is it slower to open a fragmented file
The read/write head on the disk drive has to move to lowd each part from a different track and mechanical movement slows the operation down.
Why do the gaps between files exist?
Because they formally held a file that the operating system has subsequently deleted
What is data defragmentation
When necessary an operating system will run a defragmentation routine
Moves the blocks around to make sure that the files take up a contiguous set of blocks
Why do SSD’s not require defragmentation
There are no mechanical read/write heads to move and therefore fragmentation does not slow down operation
Characteristics of CPU
Expensive
Stored on or next to CPU
