Computer Science Flashcards
what is a computer?
the definition
A computer is a machine that processes data.
what is hardware?
definition
The physical parts of a computer.
What parts of a computer does hardware involve?
examples
Internal parts:
- Motherboard
- CPU
External devices:
- keyboard
- screen
What is software?
definition
The programs that run on a computer.
How many main categories of software are there and what are they called?
There are 2 main categories.
- System software
- Application Software (apps)
What is system software?
definitions
Programs that are needed for the computer to function. (Includes the operating system)
What is the application software (apps)?
definition
Programs that enable a user to perform a specific task.
What does a computer need in order to function?
2 main things
hardware and software
what is an embedded system?
definition
An embedded system is a computer that is built into another device to control it.
What are examples of embedded systems?
AND
What is the purpose of the embedded system in the example?
- washing machine
Controls release of soap and water. Controls heater to heat water to a chosen temperature. Spins drum motor at a chosen speed for a set amount of time. - microwave
Controls the temperature/ heat to keep it the same level as the user selected - Vending machine
controls the release of contents / items. controls payment. - traffic lights
controls coloured lights shown to symbolise when traffic should stop. - lifts
controls the movement of the lift - whether it goes up or down to different floors due to the input of the user. - smart meter
Measures amount of energy used. - Auto pilot
controls altitude and direction depending on the input given by the user. - sat nav
locates and uses satellites to find your location and controls where your pin point location is on the device. Controls where the line of travel shown goes depending on your destination.
What does CPU stand for?
AND
what is it like?
(ie if it was the human body, what would the CPU be?)
The central processing unit
it is like the “brain” of the computer
What is the CPU?
definition
The CPU is a microchip that sits in the middle of the motherboard and carries out (processes) instructions stored in memory by fetching them, decoding them and executing them one at a time.
What is CPU architecture?
the main components (internal parts) of the CPU and how they interact with each other.
who’s design is what most modern CPU’s are based on?
BONUS:
- what was his profession?
- when did he come up with the design? (year)
John Von Neumann
BONUS info:
he was a mathematician and came up with the design in 1945
how many main internal components in the CPU are there?
BONUS:
what are they?
1- the control unit 2- the clock 3- The arithmetic logic unit (ALU) 4 - registers 5- Buses 6- cache memory
what is the control unit?
definition
In the CPU
fetches instructions from memory. and decodes them one at a time. It also controls the flow of data between the parts of the CPU, main memory and input/output devices.
what is the clock?
definition
In the CPU
The clock synchronises all parts of the CPU by sending electronic pulses at a constant rate. The number of clock “ticks” per second is called the clock speed and is measured in Hertz.
What is the arithmetic logic unit?
definition
In the CPU
The ALU carries out arithmetic calculations such as addition, subtraction and binary shifts. It can also do logical comparisons such as “greater than”, “less than”, AND, OR and NOT.
What are the registers called and are?
definitions and what they are
In the CPU.
Registers are small pieces of internal memory which hold instructions, data or memory addresses that are currently being used by the CPU.
- program counter
- MAR (memory address registers)
- MDR (memory data register)
- accumulator
In the CPU register what is the
program counter?
(definition)
holds the memory address of the next instruction to be executed.
In the CPU register what is the MAR?
what it stands for and definition
Memory address register
holds the memory address of the next instruction to be fetched
In the CPU register what is the MDR?
what it stands for and definition
memory data register
temporarily stores data fetched from main memory
In the CPU register what is the accumulator?
definition
temporarily stores the result of calculations completed by the ALU until they can be saved to main memory.
In the CPU what is a bus?
definition
A bus is a high speed internal connection.
Buses are used to send memory addresses, control signals and data between the processor and other components.
What is cache memory?
definition
In the CPU.
Cache memory is a small amount of very fast memory built into a CPU to store frequently used instructions. This can save time by preventing the CPU from having to fetch a common instruction from slower main memory (RAM) every time it needs it.
How does the CPU follow simple instructions?
by following the Fetch, Decode, Execute cycle.
what is fetch?
what happens / is the process?
Fetch, decode, execute cycle.
- memory address of the next instruction is copied from program counter to MAR.
- Instruction held in memory at this address is transferred to MDR.
- Program counter is incremented (increased by one) so its pointing to next instruction ready for next cycle.
what is decode?
what happens / is the process?
Fetch, decode, execute cycle.
control unit splits instruction stored in MDR into 2 parts called opcode ( instruction itself) and operand (data or memory address to use).
what is execute?
what happens / is the process?
Fetch, decode, execute cycle.
Instruction is performed (could involve loading data from memory into register, calculating something with ALU and accumulator, or saving data from a register back into memory).
what is main memory also sometimes known as?
system memory OR primary storage OR random access memory (RAM)
what does RAM stand for?
Random Access Memory
what are both RAM and cache memory?
something that happens with both of them, not definitions
Volitile