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Questions and Answers
What distinguishes an arithmetic right shift from a logical right shift?
What distinguishes an arithmetic right shift from a logical right shift?
In which type of shift operation is the sign bit preserved?
In which type of shift operation is the sign bit preserved?
What is the result of a logical left shift operation on the binary number 10100110 by 3 bits?
What is the result of a logical left shift operation on the binary number 10100110 by 3 bits?
What does the operation defined as SAL do?
What does the operation defined as SAL do?
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How are bits treated in a cycling shift (rotate) operation?
How are bits treated in a cycling shift (rotate) operation?
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Which operation can speed up certain arithmetic operations?
Which operation can speed up certain arithmetic operations?
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What happens during an arithmetic left shift?
What happens during an arithmetic left shift?
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What is the output of a right rotate operation on the binary number 10100110 by 3 bits?
What is the output of a right rotate operation on the binary number 10100110 by 3 bits?
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What does the DEC instruction do?
What does the DEC instruction do?
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Which operation updates the status flags without altering the operands?
Which operation updates the status flags without altering the operands?
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What is the effect of the NEG instruction on the operand?
What is the effect of the NEG instruction on the operand?
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In the context of arithmetic operations, what does the INC instruction perform?
In the context of arithmetic operations, what does the INC instruction perform?
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Which flag is NOT affected by the ADD instruction?
Which flag is NOT affected by the ADD instruction?
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What does the CMP instruction compare?
What does the CMP instruction compare?
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Which operation is performed last in the sequence provided for arithmetic operations?
Which operation is performed last in the sequence provided for arithmetic operations?
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Which of the following operations does NOT use decimal mode when the D flag is set?
Which of the following operations does NOT use decimal mode when the D flag is set?
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What is the purpose of the NOT instruction?
What is the purpose of the NOT instruction?
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Which operation is performed by the AND instruction?
Which operation is performed by the AND instruction?
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In which registers can unsigned division results be stored?
In which registers can unsigned division results be stored?
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What is the characteristic of logic instructions in terms of flags?
What is the characteristic of logic instructions in terms of flags?
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How does the INC instruction function?
How does the INC instruction function?
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Which multiplication instruction performs an unsigned integer multiplication?
Which multiplication instruction performs an unsigned integer multiplication?
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What is the function of the DIV instruction?
What is the function of the DIV instruction?
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Which of the following instructions preserves the state of the CF flag?
Which of the following instructions preserves the state of the CF flag?
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What does the OR operation do with its operands?
What does the OR operation do with its operands?
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What flags does the XOR operation affect?
What flags does the XOR operation affect?
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In a logical shift left operation, what happens to the bit on the leftmost end?
In a logical shift left operation, what happens to the bit on the leftmost end?
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How does the ROL instruction manipulate bits?
How does the ROL instruction manipulate bits?
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What does the RCR instruction do?
What does the RCR instruction do?
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What happens when the TEST instruction is executed?
What happens when the TEST instruction is executed?
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What does the ROL instruction leave unchanged?
What does the ROL instruction leave unchanged?
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Which operation treats the CF flag as a 1-bit extension during the shifting process?
Which operation treats the CF flag as a 1-bit extension during the shifting process?
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Study Notes
Arithmetic Operations
- Basic Arithmetic Operations: Add, subtract, multiply, and divide.
- Arithmetic instructions may involve data transfers to position operands for ALU input and deliver ALU output.
Common x86 Arithmetic Instructions
- ADD Dest, Source: Adds the destination and source operands, storing the result in the destination operand.
- SUB Dest, Source: Subtracts the source from the destination and stores the result in the destination operand.
- MUL Op: Performs an unsigned integer multiplication of the operand by the AL, AX, and EAX registers.
- IMUL Op: Performs a signed integer multiplication.
- DIV Op: Divides unsigned values in the AX, DX:AX, EDX:EAX, or RDX:RAX registers (dividend) by the source operand (divisor).
- IDIV Op: Divides signed integers.
- DEC Op: Subtracts 1 from the destination operand, preserving the state of the CF flag.
- NEG Op: Replaces the value of the operand with (0 – operand), using two's complement representation.
- CMP Op1, Op2: Compares two operands by subtracting the second operand from the first.
CMP Instruction Details
- Determines if the destination operand is greater than, equal to, or less than the source operand.
- Updates status flags (C, P, A, Z, S, O).
- It does not alter either of the operands.
- It can be followed by a conditional jump instruction or a set condition instruction.
- It does not use decimal mode if the D flag is set.
- It does not affect the value of the V flag.
- Supports all addressing modes.
Logic and Shift Operations
- Logic and shift operations are referred to as bit manipulation instructions.
- They operate on a bit-by-bit basis.
- Logic instructions can set, clear, complement, invert, and isolate operands.
- All logic instructions, except NOT, affect flag bits.
Common x86 Logic Instructions
- NOT Op: Inverts each bit of the operand.
- AND Dest, Source: Performs a bitwise AND operation on the destination and source operands, storing the result in the destination operand.
- OR Dest, Source: Performs a bitwise OR operation on the destination and source operands, storing the result in the destination operand.
- XOR Dest Source: Performs a bitwise XOR operation on the destination and source operands, storing the result in the destination operand.
- TEST Op1, Op2: Performs a bitwise AND operation on two operands, setting the S, Z, and P status flags.
Logical Shifts
- Shift bits left or right, losing the bit shifted out on one end and shifting in a zero on the other.
- Useful for isolating fields within a word.
Arithmetic Shifts
- Treat data as a signed integer.
- Do not shift the sign bit during right shift.
- Replicate the sign bit in the next position during a right arithmetic shift.
- Perform a logical left shift on all bits except the sign bit during a left arithmetic shift.
- Speed up certain arithmetic operations.
Cycling Shift (Rotate)
- Preserve all bits being operated on.
- Used to bring each bit successively into the leftmost bit for identification.
Common x86 Shift and Rotate Instructions
- SAL Op, Qty: Shifts the bit positions to the left, clearing the empty bit positions.
- SHR Op, Qty: Shifts the bit positions to the right, filling vacant positions with 0.
- SAR Op, Qty: Shifts the bit positions to the right, filling vacant positions with the sign bit value.
- ROL Op, Qty: Rotates bits to the left, with wraparound. The CF flag is loaded with the last bit shifted out.
- ROR Op, Qty: Rotates bits to the right, with wraparound. The CF flag is loaded with the last bit shifted out.
- RCL Op, Qty: Rotates bits to the left, including the CF flag, with wraparound. Treats the CF flag as a 1-bit extension on the upper end of the operand.
- RCR Op, Qty: Rotates bits to the right, including the CF flag, with wraparound. Treats the CF flag as a 1-bit extension on the lower end of the operand.
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Description
Test your knowledge of basic arithmetic operations and x86 assembly language instructions. This quiz covers key operations such as addition, subtraction, and multiplication, along with their corresponding assembly instructions. Perfect for students and enthusiasts of computer architecture and programming.