1.1 Systems Architecture

Question 1

What is the fetch instruction of the fetch-execute cycle?

Answer 1

1. Memory address is copied from the program counter to the MAR.
2. The instruction stored in the MAR is copied to the MDR.
3. The program counter is incremented by 1 to point to the address of the next instruction, ready for the next cycle.

Question 2

What is the decode instruction in the fetch-execute cycle?

Answer 2

1. The instruction in the MDR is decoded by the CU.
2. The CU may then prepare for the next step like loading values into the MAR / MDR.

Question 3

What is the execute instruction in the fetch-execute cycle?

Answer 3

The instruction is performed. (Load data from memory, write data to memory, calculations / logic operation using ALU, change the address in the PC or halt the program.)

Question 4

What is Von Neumann architecture?

Answer 4

Describes a system where the CPU runs programs stored in memory and these programs consist of instructions and data which are stored in memory addresses. Only uses one memory for both the instructions and data.

Question 5

What are the different levels of cache memory?

Answer 5

-L1 is the quickest but has the lowest capacity.
-L2 is slower than L1 but higher capacity.
-L3 is slower than L2 but higher capacity.

Question 6

What are the registers in the CPU?

Answer 6

A small amount of RAM contained within the processor which temporarily holds tiny bits of data needed by the CPU and is very quick to read / write to, much faster than any other form of memory.

Question 7

What does the processing power of a CPU depend on?

Answer 7

-Clock speed.
-Number of cores.
-Cache size.

Question 8

What is cache?

Answer 8

-Small amount of fast RAM built directly into the processor to temporarily hold instructions the processor is likely to reuse.
-This allows for faster processing as the processor does not have to wait for the data and instructions to be fetched from the RAM.
-Low capacity and expensive compared to RAM and secondary storage.

Question 9

What is the accumulator?

Answer 9

Stores intermediate results of calculations in the ALU / holds the number you’re currently working on.

Question 10

What is the ALU (Arithmetic Logic Unit)?

Answer 10

Does all the calculations like arithmetic operations, comparing numbers, logic operations, and binary shifts.

Question 11

What is the CPU?

Answer 11

Processes all of the data and instructions that make the system work.

Question 12

What is the CU (Control Unit)?

Answer 12

-Manages the fetching, decoding and execution of program instructions through the fetch-execute cycle.
-Controls the flow of data inside (to registers, ALU, cache) and outside the CPU (to main memory and input / output devices).

Question 13

What is the MAR (Memory Address Register)?

Answer 13

Holds the address of the current instruction that is to be fetched from memory, or the address in memory to which data is to be transferred.

Question 14

What is the MDR (Memory Data Register)?

Answer 14

Holds the contents found at the address held in the MAR, or data which is to be transferred to primary storage.

Question 15

What is the memory of the CPU?

Answer 15

Holds the program instructions and the program data.

Question 16

What is the PC (Program Counter)?

Answer 16

Holds the memory address of the instruction for each cycle and increments by 1 each time.

Question 17

What is the clock speed of a CPU? (Hz)

Answer 17

The number of instructions a single processor core can carry out per second.

Question 18

How does clock speed affect the performance of a CPU?

Answer 18

The higher the clock speed, the greater the number of instructions that can be carried out per second.

Question 19

What is the core of a CPU?

Answer 19

A single processing unit within the CPU that can execute instructions.

Question 20

How does the number of cores affect the performance of a CPU?

Answer 20

The more cores a CPU has, the more instructions it can carry out at once, so the faster it can process a batch of data.

Question 21

How does cache size affect the performance of a CPU?

Answer 21

A larger CPU cache gives the CPU faster access to more data it needs to process.

Question 22

What are embedded systems?

Answer 22

Computers built into other devices with the purpose to control the device and to allow a user to interact with it. Designed with one particular function.

Question 23

What are typical characteristics of embedded systems?

Answer 23

-Easy to design
-Cheaper to produce
-More efficient than general purpose computer.
-Hard to upgrade.

Question 24

What are examples of embedded systems?

Answer 24

-GPS
-Dishwasher
-Central heating systems
-Washing machine

Question 25

What is a general purpose computer?

Answer 25

Designed to perform many tasks.

Question 26

What is the address bus?

Answer 26

-Carries memory addresses from the processor to other components such as primary storage and input/output devices.
-The address bus is unidirectional.

Question 27

What is the data bus?

Answer 27

-The data bus is bi-directional.
-It can carry data to main memory from the processor and vice versa.
-The data bus will transfer data to/from the address that is held on the address bus.

Question 28

What is the control bus?

Answer 28

-Carries control signals from the processor to other components.
-The control bus also carries the clock’s pulses.
-The control bus is unidirectional.