ALU 101 Instruction Set and Operations

Question 1

What is an instruction set architecture (ISA)?

Accepted Answer

The set of instructions a processor can execute, defining its programming interface

Answer

The ISA defines the complete set of machine instructions, registers, addressing modes, and data types that a processor supports.

Question 2

What does an arithmetic shift right operation do to a signed binary number?

Accepted Answer

Divides it by 2, preserving the sign bit

Answer

An arithmetic shift right shifts bits right and replicates the sign bit into the vacated positions, effectively dividing the signed value by 2.

Question 3

A logical shift left by 1 bit is equivalent to:

Accepted Answer

Multiplying by 2

Answer

A logical left shift by 1 multiplies the unsigned binary value by 2, as each bit position represents twice the value of the position to its right.

Question 4

Which type of instruction tells the ALU to compare two values?

Accepted Answer

COMPARE (CMP)

Answer

A COMPARE (CMP) instruction subtracts two operands and sets the ALU flags without storing the result, allowing conditional decisions.

Question 5

What addressing mode uses the value in a register as the memory address to access?

Accepted Answer

Register indirect addressing

Answer

Register indirect addressing uses the value stored in a register as the effective memory address from which to load or store data.

ALU 101 - Arithmetic Logic Unit 101 Exam Practice Test