Assembly Instruction Set Categories and Functions

Posted by Anonymous and classified in Computers

Written on July 31, 2025 in English with a size of 5.73 KB

🧾 Data Transfer Instructions

These instructions are used to move data between registers, memory, and I/O ports.

Instruction	Use
`MOV`	Transfer data between registers or memory locations
`PUSH` / `POP`	Perform stack operations (store/retrieve data)
`XCHG`	Exchange contents of two operands
`IN` / `OUT`	Input from or output to a port
`LEA`	Load Effective Address
`LDS` / `LES`	Load Pointer and Segment Register
`XLAT`	Translate byte using a lookup table

These instructions perform basic mathematical operations.

Instruction	Use
`ADD` / `SUB`	Addition / Subtraction
`ADC` / `SBB`	Add/Subtract with Carry/Borrow
`INC` / `DEC`	Increment / Decrement a value
`MUL` / `IMUL`	Unsigned / Signed Multiplication
`DIV` / `IDIV`	Unsigned / Signed Division
`NEG`	Two's Complement (Negation)
`CMP`	Compare operands (sets flags)
`DAA` / `DAS`	Decimal Adjust After Addition/Subtraction
`AAA` / `AAS`	ASCII Adjust After Addition/Subtraction

These instructions perform logical and bit-level operations on data.

Instruction	Use
`AND`, `OR`, `XOR`, `NOT`	Perform Bitwise Logic Operations
`TEST`	Logical AND (sets flags, no result stored)
`SHL` / `SAL`	Shift Left (Logical/Arithmetic)
`SHR` / `SAR`	Shift Right (Logical/Arithmetic)
`ROL` / `ROR`	Rotate Left/Right
`RCL` / `RCR`	Rotate Through Carry Flag

These instructions alter the flow of program execution.

Instruction	Use
`JMP`	Perform an Unconditional Jump
`CALL` / `RET`	Procedure Call and Return
`INT` / `IRET`	Software Interrupt and Return
`JC`, `JNC`, `JZ`, `JNZ`, etc.	Conditional Jumps Based on Flags

These instructions facilitate repetitive execution of code blocks.

These instructions are designed for efficient manipulation of strings (sequences of bytes or words).

Instruction	Use
`MOVSB` / `MOVSW`	Move Byte/Word from Source to Destination
`LODSB` / `LODSW`	Load Byte/Word into `AL`/`AX` Registers
`STOSB` / `STOSW`	Store Byte/Word from `AL`/`AX` Registers
`SCASB` / `SCASW`	Scan String for a Specific Value
`CMPSB` / `CMPSW`	Compare Two Strings

These instructions are often used with REP, REPE, or REPNE prefixes for repetition.

These instructions allow direct control over the processor's flag register.

Instruction	Use
`CLC`, `STC`, `CMC`	Clear, Set, or Complement Carry Flag
`CLD`, `STD`	Clear or Set Direction Flag
`CLI`, `STI`	Clear or Set Interrupt Flag
`LAHF`, `SAHF`	Load/Store Flags to/from `AH` Register
`PUSHF`, `POPF`	Push/Pop Flags to/from Stack

These instructions manage the processor's state and operations.

Instruction	Use
`NOP`	Perform No Operation
`HLT`	Halt the Processor
`WAIT`	Wait for a Hardware Signal
`LOCK`	Lock Bus for Atomic Operations
`ESC`	Escape to Coprocessor

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