Computer Architecture

Question 1

What are the four main sub-systems in the Von Neumann Architecture?

Answer 1

Memory, ALU(Arithmetic Logic Unit), Control Unit and Input / Output System (I/O)

Question 2

What is a bus?

Answer 2

A bus is a set of wires, which interconnects all the components of a computer

Question 3

What are the three types of bus and what are their functions?

Answer 3

• Address bus – Moves memory locations or memory “addresses” of data between different components (typically 32-bit or 64-bit)
• Data bus – Moves the content of memory addresses between different components (including both data and instructions)
• Control bus – Determines the direction of data flow and when components can access the bus (i.e., the order)

Question 4

What does the clock in a computer do and what is it measured in?

Answer 4

The clock synchronizes the activities of its components, and its measured is MegaHertz (MH) of GigaHertz (GH)

Question 5

What are the functions of the four subsets in the Von Neumann Architecture?

Answer 5

Memory The unit that stores and retrieves instructions and data.
CPU: The unit that houses two separate components:
i. The control unit: Repeats the following 3 tasks:
a. Fetches an instruction from memory
b. Decodes the instruction
c. Executes the instruction
ii. The arithmetic/logic unit (ALU): Performs mathematical and logical operations.
Input / Output (I/O) devices: Handle communications with the outside world.

Question 6

What is a cell of memory?

Answer 6

A cell is the smallest addressable unit of memory – i.e., one cell can be read from memory or one cell can be written into memory, but nothing smaller. The previous content is
always overwritten

Question 7

What is the function of a cell?

Answer 7

Each cell has an address, starting at 0 and increasing
by 1 for each cell. A cell with a low address is just as accessible as one with a high address- hence the name RAM. The width of the cell determines how many bits can be read or written in one machine operation
MAR: Memory Address Register
MDR: Memory Data Register

Question 8

What does the ALU do?

Answer 8

Performs basic arithmetic operations: addition, subtraction,
multiplication, and division and performs logical operations: AND, OR, and NOT

Question 9

What does the Control Unit do?

Answer 9

The Control Unit is the unit that handles the central work of the computer. It also implements the fetch-decode-execute cycle

Question 10

What are the two registers in the control unit called and what are their functions?

Answer 10

The two registers are called the Instruction Register and Program Counter. The Instruction Register(IR) contains the instruction that is being executed. The Program Counter (PC) contains the address of the next instruction to be executed

Question 11

What is an interrupt?

Answer 11

When an event of higher priority occurs, the CPU is alerted . Interrupts can have priorities, and high-priority interrupts cannot be ignored.

Question 12

What can trigger an interrupt?

Answer 12

Interrupts can be triggered by I/O requests, arithmetic errors
(such as division by zero), or when an invalid instruction is
encountered

Question 13

Define instruction

Answer 13

An operation performed by the CPU

Question 14

What does RISC stand for and what is it?

Answer 14

Reduced Instruction Set Computers. It’s an instruction set as small and simple as possible which minimizes the amount of circuitry, leading to faster computers

Question 15

What does CISC stand for and what is it?

Answer 15

Complex Instruction Set Computers. It’s an instruction set which carries out more instructions due to how complex it is. Each instruction can do more work, but it requires more circuitry