Micro 3-4

Lnte ni nga pangabuhi

MOV instruction

is a common and flexible instruction.

MOV

provides a basis for explanation of data addressing modes

Opcode or operation code

tells the microprocessor which operation to perform

Register Addressing

The most common form of data addressing.

AH, AL, BH, BL, CH, CL, DH, and DL.

8-bit register names used with register addressing

AX, BX, CX, DX, SP, BP, SI, and DI.

16-bit register names

EAX, EBX, ECX, EDX, ESP, EBP, EDI, and ESI.

Extended 32-bit register names are

RAX, RBX, RCX, RDX, RSP, RBP, RDI, RSI, and R8 through R15.

64-bit mode register names are

do not change.

The source register’s contents ___.

do change.

The destination register’s contents ___

CMP and TEST instructions

The contents of the destination register or destination memory location change for all instructions except the __*and*__ _____

MOV BX, CX instruction

The ____ does not affect the leftmost 16 bits of register EBX.

Immediate

Term that implies that data immediately follow the hexadecimal opcode in the memory.

Immediate data

data transferred from a register or memory location are variable data Immediate addressing

In symbolic assembly language, the symbol \# precedes immediate data in some assemblers.

If hexadecimal data begin with a letter, the assembler requires the data start with a 0.

- to represent a hexadecimal F2, 0F2H is used in assembly language

Decimal data are represented as is and require no special codes or adjustments.

An ASCII-coded character or characters may be depicted in the immediate form if the ASCII data are enclosed in apostrophes.

Binary data are represented if the binary number is followed by the letter B

Each statement in an assembly language program consists of four parts or fields.

Label

it is the leftmost field. Used to store a symbolic name for the memory location it represents

Label

appears in a program to identify the name of a memory location for storing data and for other purposes.

Opcode field

designed to hold the instruction, or opcode.

Operand field

Right of the opcode field. Contains information used by the opcode.

Comment field or the final field

contains a comment about the instruction(s).

semicolon (;)

Comments always begin with a ___

Direct Data Addressing

Applied to many instructions in a typical program.

Direct addressing and Displacement addressing

Two basic forms of direct data addressing:

Direct addressing

which applies to a MOV between a memory location and AL, AX, or EAX

Displacement addressing

which applies to almost any instruction in the instruction set

Address

is formed by adding the displacement to the default data segment address or an alternate segment address.

Direct addressing with a MOV instruction

transfers data between a memory location, located within the data segment, and the AL (8-bit), AX (16-bit), or EAX (32-bit) register.

Direct addressing

the instruction is usually a 3-byte long instruction

Displacement Addressing

Almost identical to direct addressing, except the instruction is 4 bytes wide instead of 3.

Displacement Addressing

In 80386 through Pentium 4, this instruction can be up to 7 bytes wide if a 32-bit register and a 32-bit displacement are specified.

Displacement Addressing

This type of direct data addressing is much more flexible because most instructions use it.

Register Indirect Addressing

Allows data to be addressed at any memory location through an offset address held in any of the following registers: BP, BX, DI, and SI.

Data segment

is used by default with register indirect addressing or any other mode that uses BX, DI, or SI to address memory.

Stack segment

If the BP register addresses memory, this is used by default.

Special assembler directive

In some cases, indirect addressing requires this in order to specify the size of the data

BYTE PTR, WORD PTR, DWORD PTR, or QWORD PTR.

Special assembler directive

Memory pointer (PTR)

These directives indicate the size of the memory data addressed by the \____

Indirect addressing

often allows a program to refer to tabular data located in memory.

Base-Plus-Index Addressing

Similar to indirect addressing because it indirectly addresses memory data.

The base register

often holds the beginning location of a memory array

Index register

holds the relative position of an element in the array

Stack segment register and BP

Whenever BP addresses memory data, both the \______ and \____ generate the effective address.

Register Relative Addressing

Similar to base-plus-index addressing and displacement addressing

Register Relative Addressing

data in a segment of memory are addressed by adding the displacement to the contents of a base or an index register (BP, BX, DI, or SI)

Addressing Array Data with Register Relative

It is possible to address array data with register relative addressing.

Base Relative-Plus-Index Addressing

adds a displacement and uses a base register and an index register to form the memory address.

Base Relative-Plus-Index Addressing

This type of addressing mode often addresses a two-dimensional array of memory data

Addressing Data with Base Relative-Plus-Index

Least used addressing mode.

Addressing Data with Base Relative-Plus-Index

This addressing mode is too complex for frequent use in programming.

Addressing Arrays with Base Relative-Plus-Index

Suppose a file of many records exists in memory, each record with many elements.

Addressing Arrays with Base Relative-Plus-Index

Displacement addresses the file, base register addresses a record, the index register addresses an element of a record

Scaled-Index Addressing

Unique to 80386

Scaled-Index Addressing

uses two 32-bit registers (a base register and an index register) to access the memory

Scaling factor

1x, 2x, 4x, 8x

RIP Relative Addressing

Uses the 64-bit instruction pointer register in the 64-bit mode to address a linear location in the flat memory model.

RIP Relative Addressing

Inline assembler program available to Visual does not contain any way of using this mode or any other 64-bit addressing mode

The Microsoft Visual

does not at present support developing 64-bit assembly code.

Data Structures

Used to specify how information is stored in a memory array.

Data Structures

a template for data

STRUB assembly language directive, ENDS statement

The start of a structure is identified with the \___ and the end with the \___

PROGRAM MEMORY ADDRESSING MODES

Used with the JMP (jump) and CALL instructions.

direct, relative, and indirect

Three distinct forms of program memory addressing mode

Direct Program Memory Addressing

Used for all jumps and calls by early microprocessor; also used in high-level languages, such as BASIC.

Direct Program Memory Addressing

The microprocessor uses this form, but not as often as relative and indirect program memory addressing.

Direct Program Memory Addressing

The instructions for direct program memory addressing store the address with the opcode

Intersegment jump

is a jump to any memory location within the entire memory system

Far jump

it can jump to any memory location for the next instruction

Intersegment or far CALL instruction

The only other instruction using direct program addressing.

Label

name of a memory address

CALL instruction

refers to the location that is called or jumped to instead of the actual numeric address.

Relative Program Memory Addressing

Not available in all early microprocessors, but it is available to this family of microprocessors.

Relative Program Memory Addressing

The term relative means “relative to the instruction pointer (IP)”.

Relative Program Memory Addressing

The JMP instruction is a 1-byte instruction, with a 1-byte or a 2-byte displacement that adds to the instruction pointer

Indirect Program Memory Addressing

The microprocessor allows several forms of program indirect memory addressing for the JMP and CALL instructions.

Indirect Program Memory Addressing

In 80386 and above, an extended register can be used to hold the address or indirect address of a relative JMP or CALL.

Indirect jump

If a relative register holds the address, the jump is considered to be an\____.

Indirect jump, intrasegment jump, double-indirect jump

Types of JUMP

Stack

plays an important role in all microprocessors. It holds data temporarily and stores return addresses used by procedures

LIFO (last-in, first-out)

Stack memory is \___ memory

LIFO (last-in, first-out)

describes the way data are stored and removed from the stack

Push instruction, POP instruction

Data are placed on the stack with a __; removed with a \_______.

The stack pointer (SP or ESP), the stack segment register (SS)

Stack memory is maintained by two registers:

Machine Language

Native binary code microprocessor uses as its instructions to control its operation.

1 to 13 bytes

Machine language instructions vary in length from \____

100,000

Over \___ variations of machine language instructions.

Binary opcode

general form of the opcode: First 6 bits of the first byte are the \___

direction (D) of the data flow, byte or word (W)

Remaining 2 bits indicate the \____, and indicate whether the data are a \_____

MOD Field

Specifies addressing mode and whether a displacement is present with the selected type.

Special Addressing Mode

occurs when memory data are referenced by only the displacement mode of addressing for 16-bit instructions

00, 110

When an instruction has only a displacement, MOD field is always __; R/M field always \___.

Scaled-index byte

indicates additional forms of scaled-index addressing.

Scaled-index byte

mainly used when two registers are added to specify the memory address in an instruction

32K

A scaled-index instruction has\___ possible combinations.

PUSH/POP

Important instructions that store and retrieve data from the LIFO (last-in, first-out) stack memory.