systems architecture

Question 1

central processing unit (CPU)

Answer 1

The CPU carries out processing on the computer, it does this by fetching and executing instructions.

Question 2

control unit (CU)

Answer 2

coordinates and controls all of the activities taking place within a CPU

Question 3

arithmetic logic unit (ALU)

Answer 3

where the actual arithmetic operations are executed and Logic (comparison) operations.

Question 4

register

Answer 4

temporary storage area built into the CPU

Question 5

program counter (PC)

Answer 5

holds the address of the next instruction to be executed

Question 6

memory address register (MAR)

Answer 6

holds the memory address of the current instruction to be executed and the address of the data to be used in the instruction

Question 7

memory data register (MDR)

Answer 7

holds the actual instruction and data that is stored in the RAM

Question 8

accumulator (ACC)

Answer 8

holds the result of the instruction, temporarily stores arithmetic and logic results

Question 9

cache

Answer 9

hardware or software component that stores data so that future requests for that data can be loaded faster (small amount of very fast, expensive memory in the CPU)

Question 10

FDE cycle

Answer 10

The Processor fetches the next instruction to be executed from memory.
The address of the next instruction is stored in the Program Counter. The PC is stored in the MAR.
The Program counter is incremented.
The instruction is stored in the MDR.
The instruction is decoded.
The instruction is executed.
And the cycle begins again.

Question 11

clock speed

Answer 11

FDE cycles per second measured in Hz
The higher the clock speed, the more instructions can be executed per second as every operation starts on a clock pulse. This improves the performance.

Question 12

number of cores

Answer 12

The more cores there are, the more processors there are processing data at the same time.

More cores will improve performance in some circumstances, but the computer system may not always be able to take advantage of more than one core

Question 13

level 1 cache

Answer 13

extremely fast but small (between 2-256kb) located in the CPU. each core will have its own level 1 cache. it is used about 50% of the time

Question 14

level 2 cache

Answer 14

it is fast but slower than level 1 cache, about 256kb - 8mb and is usually given to each core. it is used about 90% of the time and the size of level 2 cache is a major factor in determining the performance of the CPU

Question 15

level 3 cache

Answer 15

the slowest type of cache but faster than RAM and stores about 4-50mb. this cache is shared between all the cores in the CPU

Question 16

embedded systems

Answer 16

an embedded computer is a single microprocessor that includes ROM, RAM and a CPU.
A computer system which is built into another device and cannot be changed without replacing the hardware in which it is embedded

Question 17

characteristics of embedded systems

Answer 17

typically slow, has one purpose and cannot install new software, program stored on ROM, typically very reliable

Question 18

current instruction register (CIR)

Answer 18

it is part of the control unit that holds the instruction currently being executed or decoded

Question 19

Von Neumann architecture

Answer 19

program instructions and the data the programs are using are both stored in the same memory

Question 20

cache

Answer 20

Small area of memory which is either on the CPU or between the CPU and RAM.
Purpose is to store the most frequently accessed / recently accessed instructions and data needed by the processor.
Cache is faster than RAM.
If data is in the cache the processor can access it faster than RAM.
If an instruction is not located in the cache the processor has to retrieve it from RAM.