CPU Components and Functions

10 Questions

In a Von-Neumann Architecture, which of the following is a characteristic?

Shared bus for data and instructions

What is the main purpose of Instruction Pipelining?

To achieve higher execution speed at the same clock speed

What happens to the Stack Pointer during the first PUSH operation?

It points to the last memory location in SRAM

What is the Instruction Life Cycle?

The sequence of steps the CPU takes to execute an instruction

What type of architecture do microcontrollers most often use?

Modified Harvard-based architecture

What is the benefit of Instruction Pipelining?

Increased execution speed at the same clock speed

What is the purpose of the Stack Pointer?

To point to the last memory location in SRAM

In a Harvard Architecture, what is the main difference from Von-Neumann Architecture?

Separate memory spaces for data and instructions

What happens to the Stack Pointer after a POP operation?

It points to the previous memory location

What is the main advantage of using a Harvard Architecture in microcontrollers?

Faster data access and processing

Study Notes

Central Processing Unit (CPU)

The CPU has several units: Instruction Decoder (Control Unit), Accumulator Register, Register File, Arithmetic Logic Unit (ALU), and SFR Registers.
The Instruction Decoder (Control Unit) converts instructions from program memory into a format the ALU can understand and generates control signals.

Instruction Decoder (Control Unit)

Controls the flow of data through the processor and coordinates the activities of other units.
Generates control signals for the ALU and Register File.

Accumulator Register

A working desk for storing data for operations like addition, shift, and subtraction.
Closely related to the operation of the ALU.

Register File

A group of registers (e.g., 32 registers R0-R31 in AVR CPU).
Can read two registers at once by supplying addresses and writing to a register using data inputs and setting WR=1.

Instruction Cycle

1. Decode Instruction: Control Unit generates control signals for the ALU and Register File.
1. Execute Instruction: ALU executes the instruction.
1. Write Back Instruction: Control Unit generates control signals to store the result in the Register File.

Arithmetic Logic Unit (ALU)

Part of the CPU responsible for performing calculations and executing arithmetic, logic, and shift instructions.
Arithmetic instructions: addition, subtraction, shifting operations.
Logic instructions: AND, OR, XOR, NOT operations.

Stack Pointer and Stack Operations

The Stack Pointer must be initialized to point to the last memory location in SRAM.
PUSH and POP operations update the stack.

Instruction Pipelining and CPU Architecture

Instruction Pipelining: continuous and parallel streaming of instructions to the CPU for higher execution speed at the same clock speed.
The AVR CPU uses a modified Harvard Architecture with parallel instruction fetches and executions.
CPU Architecture: Von-Neumann and Harvard architectures exist, with microcontrollers often using a Harvard or modified Harvard-based architecture.