Components of a computer system (PAPER 1) Flashcards
What is a computer
A machine that processes data
What is the purpose of a computer
to take data, process it and then output it
What does a computer system consist of
hardware and software that work together to process data and complete tasks
What is hardware
physical things that make up a computer system
What is software
programs or applications that a computer system runs
What are external pieces of hardware known as
peripherals
What is a general purpose computer
a computer designed to perform many tasks
What is a dedicated system computer
a computer designed to perform one particular function
What is an embedded system
a computer inside a larger system
What are the two types of computer
general purpose and dedicated system
What type of computer do embedded systems tend to be
dedicated system
What is a control system
a system that monitors and controls machinery in order to achieve a desired result
What are the advantages of using a dedicated system instead of a general purpose computer
- cheaper to produce
- easier to design
- more efficient
What are nine key parts to a desktop PC
- power supply
- case cooling fan
- CPU heat sink, cooling fan
- CPU
- Graphics card
- Motherboard
- Hard Disk Drive
- RAM
- Optical Drive
What is the purpose of a power supply
supplies power to motherboard and other hardware
What is the purpose of a case cooling fan
to extract heat from the computer case
What is the purpose of a CPU heat sink and cooling fan
to keep the CPU at a constant temperature
What is the motherboard
The main circuit board where hardware is connected
What is the optical drive used for
for read / writing optical discs
What does CPU stand for
Central Processing Unit
What is the overall job of the CPU
to process the data and instructions that make the system work
What are the two main types of architecture of CPU
Harvard and Von Neumann
What are the three main parts of the CPU
- control unit
- Arithmetic Logic Unit
- Cache
What are the two main jobs of the control unit
- manage fetching, decoding, execution of program instruction
- control the flow of data inside and outside the CPU
What does the ALU do
- additions and subtractions
- multiplying/ division using add/subtract
- comparing size of numbers
- logic operations e.g. AND, OR, NOT
- binary shifts
What is the Cache
very fast memory in the CPU
How does the cache’s speed compare to other forms of memory
slower than registers, faster than RAM
What is the cache used for
to store regularly used data for quick access - CPU checks cache first before going to RAM
What is the drawback of using cache
it has a low capacity and is very expensive
What are the three levels of cache memory, how do they compare
- L1 - quickest, lowest capacity
- L2 - slower, larger capacity
- L3 - slowest, largest capacity
- What do registers do
- How fast are they
- What are the four key types
hold tiny bits of data needed by the CPU
very fast to read / write
- program counter
- memory address register
- memory data register
- accumulator
Where is the accumulator stored
in the ALU
What is the ALU
arithmetic logic unit
What is the CU
control unit
When and who created the Von Neumann architecture
John Von Neumann in 1945
What do programs consist of
instructions and data stored in memory addresses
What does PC stand for (register)
program counter
what does the PC do
holds the memory address of the instruction for each cycle
What does the accumulator do
stores the intermediate results of calculations in the ALU
What is a key feature special to the Von Neumann architecture
it only uses one memory for both the data and the instructions
What does MAR stand for
memory address register
What does MDR stand for
memory data register
What does the MAR do
holds any memory address about to be used by the CPU
What does the MDR do
holds the actual data or instruction. This may have been fetched from memory , or be waiting to be written to memory
What does the memory hold in a Von Neumann system
program instructions and program data
What holds the PC
Control Unit
What happens during the Fetch Instruction in a Fetch - Execute cycle
- Copy memory address from program counter to MAR
- Copy the instruction stored in MAR address to MDR
- increase program counter to point to address of next instruction ready for next cycle
What happens during the Decode Instruction in a Fetch - Execute cycle
instruction in MDR is decoded by CU