System architecture, memory and storage Flashcards
What is the purpose of the CPU?
To execute instructions stored in the memory, through the FDE cycle.
Explain each stage of the FDE cycle
Fetch, The instruction is fetched from memory
Decode, The instruction is interpreted
Execute, The instruction is carried out
What is the function of the ALU?
The Arithmetic Logic Unit carries out mathematical and logical operations such as AND, OR and Binary shifts.
What is the function of the CU?
The Control Unit co-ordinates the FDE cycle by controlling the sequence of instructions,regulating processor timing etc.
List the special-purpose registers found in the CPU
MAR - Memory Address Register
MDR - Memory Data Register
PC - Program Counter
Accumulator
What is the funtion of the MAR?
Holds the location in memory of the current instruction or data to be fetched or stored.
What is the function of the MDR?
Temporarily holds data when fetched from or to be sent to memory.
What is the function of the PC?
Holds the memory addess of the next instruction to be processed.
What is the function of the accumulator?
Stores the results of operations carried out in the ALU.
State the three main factors affecting CPU performance
Clock Speed
Cache Size
Number of Cores
Describe how Clock Speed affects CPU preformance
Everything the processor does occurs on a tick therefore a faster clock means more instructions FDE’d
Measured in GHz (n billion of cycles per second)
Describe how Cache Memory affects CPU performance
As Cache stores frequently used memory and can be accessed faster than RAM, the more data stored in the Cache the more efficient the CPU
Order the following by ascending access speed:
Physical RAM, CPU registers , Disc Storage, Cache
CPU registers
Cache
Physical RAM
Disc Storage
Order the following by ascending cost per byte:
Physical RAM, CPU registers , Disc Storage, Cache
CPU registers
Cache
Physical RAM
Disc Storage
Order the following by ascending capacity:
Physical RAM, CPU registers , Disc Storage, Cache
Disc Storage
Physical RAM
Cache
CPU registers
Describe how number of cores affects CPU performance
Each core can process 1 operation per clock cycle therefore a dual core for example could theoretically perform 2 simultaneously.
Explain why a dual core processor or 2x clock speed may not translate to 2x CPU performance
- Software must support multiple cores
- The result of an operation may be required for the next
- Bottlenecks such as Cache size
What is an embedded system and it’s characteristics?
A reliable, minimal resource computer built into a piece of equipment to perform a specific function.
They cannot be modified once manufactured as they are controlled by ROM
Outline the differences between RAM and ROM
RAM - Volatile (all data lost when computer turned off), Used for working instructions and data, can be read from and written to
ROM - Non-volatile, used for start-up instructions and embedded systems, can only be read from
State what is meant by virtual memory
Virtual memory is a form of non-volatile memory, typically a part of the HDD or SSD dedicated to behave like RAM. When the program stored in the hard disk is needed it is swapped out with something else in the RAM
Ouline 3 examples of solid state storage devices
Internal Solid State
USB Memory stick
Memory Card
