10 Questions
Explain the four main stages of the instruction execution cycle in a computer's CPU.
The four main stages of the instruction execution cycle are: 1. Fetch (IF - Instruction Fetch): The CPU fetches the next instruction from memory. 2. Decode (ID - Instruction Decode): The CPU decodes the instruction to understand the operation that needs to be performed. 3. Execute (EX - Execution): The actual operation specified by the opcode is carried out. 4. Store (MEM - Memory Write/Read): This stage involves writing data to memory or fetching necessary data for instructions that read from memory.
What does the Decode (ID - Instruction Decode) stage of the instruction execution cycle involve?
The Decode stage involves extracting the opcode (operation code) of the instruction from the instruction register and understanding the operands and addressing modes that may be decoded during this stage.
During which stage of the instruction execution cycle are arithmetic or logical operations performed?
Arithmetic or logical operations are performed during the Execute (EX - Execution) stage of the instruction execution cycle.
What role does the program counter (PC) play in the Fetch (IF - Instruction Fetch) stage of the instruction execution cycle?
The program counter (PC) holds the memory address of the next instruction to be fetched from the memory.
When does the cycle of the instruction execution cycle repeat for each instruction processed by the CPU?
The cycle of the instruction execution cycle repeats for each instruction processed by the CPU after the Store (MEM - Memory Write/Read) stage.
Match the stage of the instruction execution cycle with its description:
Fetch (IF - Instruction Fetch) = The CPU fetches the next instruction from the memory and loads it into the instruction register (IR) Decode (ID - Instruction Decode) = The CPU decodes the instruction to understand what operation needs to be performed and extracts the opcode (operation code) Execute (EX - Execution) = The actual operation specified by the opcode is carried out, and data may be manipulated Store (MEM - Memory Write/Read) = If the instruction involves writing data to memory, this stage is where the write-back to memory occurs
Match the following components with their roles in the instruction execution cycle:
Program Counter (PC) = Holds the memory address of the next instruction during the Fetch stage Instruction Register (IR) = Where the fetched instruction is loaded during the Fetch stage Opcode = Identifies the operation to be performed and is extracted during the Decode stage Memory = Location from which instructions are fetched and to which data may be written during the Store stage
Match the following actions with their corresponding stages in the instruction execution cycle:
Fetching the next instruction from memory = Fetch (IF - Instruction Fetch) Decoding the instruction and extracting opcode = Decode (ID - Instruction Decode) Performing arithmetic or logical operations = Execute (EX - Execution) Writing back data to memory or fetching necessary data = Store (MEM - Memory Write/Read)
Match the description with the correct stage of the instruction execution cycle:
Carrying out the actual operation specified by the opcode = Execute (EX - Execution) Reading from memory or writing data back to memory = Store (MEM - Memory Write/Read) Understanding what operation needs to be performed and decoding the opcode = Decode (ID - Instruction Decode) Fetching the next instruction from memory and loading it into IR = Fetch (IF - Instruction Fetch)
Match the following terms with their respective meanings in the context of instruction execution cycle:
Instruction Execution Cycle = The process through which a CPU fetches, decodes, and executes instructions Machine Cycle = Another name for the instruction execution cycle, consisting of fetch, decode, execute, and store stages Opcode = The operation code extracted during the Decode stage to identify the operation to be performed Program Counter (PC) = Holds the memory address of the next instruction during the Fetch stage
Study Notes
Instruction Execution Cycle
- The instruction execution cycle consists of four main stages: Fetch (IF), Decode (ID), Execute (EX), and Memory Access (MEM) / Write Back (WB)
Fetch Stage (IF)
- The program counter (PC) plays a crucial role in this stage, providing the address of the next instruction to be fetched
- The CPU retrieves an instruction from memory at the address provided by the PC
Decode Stage (ID)
- During this stage, the instruction is decoded, and the necessary operands are identified
- The CPU determines the opcode, operands, and the type of operation to be performed
Execute Stage (EX)
- Arithmetic or logical operations are performed during this stage
- The CPU executes the instruction, using the operands and operation type determined during the Decode stage
Repeat Cycle
- The instruction execution cycle repeats for each instruction processed by the CPU
- The cycle starts again from the Fetch stage, with the PC incremented to point to the next instruction
Component Roles
- Program Counter (PC): provides the address of the next instruction to be fetched
- Opcode: determines the type of operation to be performed
- Operands: data used in the execution of the instruction
Stage Descriptions
- Fetch (IF): retrieves an instruction from memory
- Decode (ID): decodes the instruction and identifies operands
- Execute (EX): performs arithmetic or logical operations
- Memory Access (MEM) / Write Back (WB): accesses memory and stores results
Term Definitions
- Opcode: the part of the instruction that determines the operation to be performed
- Operand: the data used in the execution of the instruction
Test your knowledge of the instruction execution cycle, which is the fundamental process for a computer's CPU to fetch, decode, and execute instructions. Learn about the four main stages: fetch, decode, execute, and store.
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