1.1 Systems architecture Flashcards
Components of the CPU and the FDE cycle
CPU stands for…
Central Processing Unit
FDE cycle stands for…
Fetch Decode Execute cycle
RAM stands for…
Random Access Memory
ROM stands for…
Read-Only Memory
What are the four registers in the Von Neumann architecture?
Memory Address Register, Memory Data Register, Accumulator and the Program counter
What are the four Acronyms for the registers in the Von Neumann architecture?
MAR,MDR,PC,ACC
What is the role of the Arithmetic Logic Unit (ALU) ?
It carries out the Arithmetic and Logical calculations of the computer e.g. add (+), subtract (-), multiply (*), divide (/), DIV, MOD, greater than (>), less than (<), equal to (==), equal to or greater than (>=), equal to or less than (<=), not equal to (!=)
What is the role of the Control Unit (CU) ?
The Control Unit (CU) decodes instructions and sends signals to control how data moves around the CPU
What is the role of the Accumulator (ACC) ?
Holds the result of the calculations performed by the ALU
What is the role of the Program Counter (PC) ?
Stores the memory address of the next
instruction
command to be executed
What is the role of the Memory Data Register (MDR) ?
Stores the data that has just been fetched from, or the data that is about to be written to, the memory
What is the role of the Memory Address Register (MAR) ?
Holds the address of where data is to be fetched or stored
What is Cache Memory?
Cache is temporary storage of frequently accessed data and instructions being read to and written from
What is Clock Speed?
Clock speed is the number of FDE cycles that are carried out per second by the CPU. Measured in Hertz/Gigahertz
How does Clock Speed affect the performance of the CPU?
Larger Clock Speed means that more FDE cycles can be carried out by the CPU per second which increases performance
How does Cache Size affect the performance of the CPU?
Larger Cache Size allows for more high speed memory meaning that instructions don’t have to go all the way to RAM (Main Memory)
How does Number Of Cores affect the Performance of the CPU?
More Cores allows for the computer to split the amount of instructions needing to be processed between its CPUs giving the illusion that they are being processed quicker
What are the negatives of having multiple Cores?
Doubling the cores, does not increase Clock Speed, many programs are not designed to make full use of multiple Cores
What does having multiple Cores allow the computer to do? (100 instructions example)
If a computer needed to process 100 instructions, then a Dual Core will split this into 2 sets of 50 instructions being done at the same time
What are Embedded systems?
Objects that have a computer system built into them with a set of instructions that CANNOT be changed (e.g. Dishwasher, fridge, washing machine, calculator)
What is the name of the Control Unit component that coordinates the CPU’s activity?
The clock
During a CPU cycle, the Arithmetic Logic Unit has been activated. During which stage of the FDE cycle was it activated?
Execute
Fetch (FDE cycle)
The instruction stored at the memory address in the PC is fetched. The memory address
address is copied to the MAR.
Fetch part 2 (FDE cycle)
The memory contents at the address are fetched into the MDR. The PC is now incremented.
