SYSTEMS ARCHITECTURE Flashcards
What is a Computer?
An electronic device that takes input, processes data, and delievers output
What is the purpose of a CPU?
The centeral processing unit fetches, decodes and executes instructions
What is the fetch stage of a CPU?
Fetch the next instruction from main memory (RAM) and bring it back to CPU
What is the decode stage of a CPU?
Inspect the instruction and work out what it is that needs doing
What is the execute stage of a CPU?
Carry out the instruction
What is the purpose of an ALU?
The arithmetic logic unit is responisble for carrying out arithmetic calculations and making logical decisions
What is the purpose of the CU?
The control unit send signal sto control how the data moves around the CPU.
What is the purpose of the cache?
The cache provides fast access to frequently used data and instructions
What is the purpose of the registers?
The registers are tiny, super fast peices of onbaord memory inside a CPU.
Each have a specific purpose
What did Von Neumann design?
He designed computers with stored programs
What is a stored program?
A stored programmed computer has changable progams
What are the key characteristics of the Von Neuman architecture?
C - CPU
I - Internal clock
O - Onboard cache
S - Single CU
A - ALU
How is data stored in memory?
Both instruction and program data are stored in the same memory in binary form
What is the program counter?
The PC always holds the address of the next instruction to be executed in memory
What is the MAR?
The memory address register holds the address of where data is to be fetched from or stored into
What is the MDR?
The memory data register holds the data fetched from or to be written to memory
What is the accumulator?
Holds the results of the calculations
Describe the fetch-execute cycle in Von Neuman’s architecture.
The program counter (PC) is checked as it holds the address of what needs to be executed
The memory address register (MAR) then fetches the instrution paired to the address from main memory (RAM) and brings it to memory data register (MDR)
The PC will then increment the address to point to next instruction
Now the instruction is in CPU, the control unit (CU) will decode the instruction to see what has to be done
Lastly the instruction is executed
What 3 factors affect the performance of the CPU?
Cache size
Clock speed
Nmber of cores
What is Clock sped and how does it affect the performance of the CPU?
Clock speed is the number of cycles per second measured in Hertz (Hz)
The faster the clock ticks, the more you can fetch and execute instructions vice versa
What is Cache size and how does it affect the performance of the CPU?
The cache is a temporary storage of data located near to the CPU. It stores recent data and instructions and is much quicker getting items from than RAM.
Is quicker than getting instructions and data from memory BUT cache is limited and has less storage –> affects CPU’s overal performance.
What is a core and how do the number of them affect the CPU’s performance?
A core is a complete copy of a CPU.
CPUs with more cores have more power to run multiple programs at once .
CPU cores have to communicate to eachother which takes time so more cores = more time. PLUS, many programs are not designed to make maximum use of every core
What is an embedded system?
An embedded system is a computer system with a dedicated function within a larger mechanical and electrical system
Give some examples of an embedded system.
Washing Machine
Microwave
Oven
Fridge
Apollo guidance computer
Traffic lights
etc
