1.1 - Architecture of the CPU

Question 1

Give some examples of Input Devices

Answer 1

Keyboard, mice, trackpads, microphone

Question 2

Give some examples of output devices

Answer 2

Monitors, speakers

Question 3

What are the main components of a computer (not based on hardware)?

Answer 3

The CPU, main memory, secondary storage, Input and Output devices

Question 4

Where is the CPU located?

Answer 4

On the motherboard (specifically the socket)

Question 5

Purpose of the CPU

Answer 5

CPU runs and processes the instructions

Question 6

How does the CPU run?

Answer 6

It runs one simple instruction at a time, which happens billions of times a second

Question 7

What was the stored program concept?

Answer 7

It was the idea of storing the program instructions as well as data in memory

Question 8

How were computers first run?

Answer 8

One instruction at a time using switches, or read in punch cards and executed one at a time

Question 9

What year was when the stored program concept was born?

Answer 9

1943-44

Question 10

What was the von Neumann architecture?

Answer 10

• Program instructions and data programs are both stored in the same memory
• CPU accesses both instructions and data from the same RAM

Question 11

What are the components of the CPU?

Answer 11

2 major components called the Control Unit and the Arithmetic-Logic Unit (ALU). There are also registers that are used to carry out these operations

Question 12

What are registers in the CPU?

Answer 12

A very fast memory location in the CPU, and cache is also located in the CPU, but although it is slower than registers, it is faster than storing memory in RAM which is much slower

Question 13

Give some registers in the CPU

Answer 13

Program Counter (PC), Memory Address Register (MAR), Memory Data Register (MDR), Accumulator (ACC)

Question 14

What does the Program Counter (PC) do?

Answer 14

Holds the address of the next instruction to be executed

Question 15

What does the Memory Address Register (MAR) do?

Answer 15

Hold the memory address of current instruction and then the data that it uses so that these can be fetched from memory

Question 16

What does the Memory Data Register (MDR) do?

Answer 16

Holds data or a program instruction temporarily when it is fetched from memory or is to be sent to memory.

Question 17

What does the accumulator (ACC) do?

Answer 17

Holds the result of an instruction before it is transferred to memory

Question 18

What is the Control Unit?

Answer 18

• Coordinates and controls all of the activities taking place within the CPU
• The control unit decode instructions and executes them
• It receives signals form the system clock
• It directs the timing and control of the other parts of the CPU, much like the conductor of the orchestra

Question 19

What is the ALU?

Answer 19

• The ALU is where the actual arithmetic operations are done

- Some operation examples are logical operations like AND, OR, NOT

Question 20

What is Fetch - Decode - Execute (FDE)

Answer 20

Repeats this process:

• Fetch an instruction from memory (program counter),
• Decodes the instruction (Control Unit),
• Executes the instruction (MAR and MDR).

Question 21

FDE - Program Counter

Answer 21

The program counter hold the address of the next instruction and then increments the value by 1 as soon as the current instruction has been fetched

Question 22

FDE - Accumulator

Answer 22

The Accumulator (ACC) is where arithmetic and logic results are temporarily stored

Question 23

FDE - MAR and MDR

Answer 23

• If data is needed to fetched (commanded by the Control Unit), the MAR is then used to hold the address of the data to be used in the current instruction.
• Then this data is fetched and copied to the MDR

Question 24

How does the MAR and MDR work together?

Answer 24

MAR knows where to look for data in RAM, the MDR keeps hold of that data until it is ready to be used by the CPU