80386DX Processor Operating Modes

Real Mode

Virtual 8086 Mode.

Protected Mode

Three Level Protection

Segment Registers(16-bit)

Offset Registers (16 Bit)

Memory used is 1 MB

Data Registers (16 Bit)

Default Mode.

Control Registers

Flag Registers Only 12 bit

AX=AL+AH

BX=BL+BH

CX=CL+CH

DX=DL+DH

CS,DS,SS,ES,FS,GS

IP,SP,BP,SI,DI

Only CR0 is present

PL1:System Services

PL 2:Custom OS Extension

PL 0: OS

PL 3: User Application Programs

Segment Registers(16 Bit)

Selector for GDTR &IDTR

Offset Register (32 BIt)

EIP,ESP,EBP,ESI,EDI

General Purpose Registers 32 BIT

AX(Acummalator),BX,CX(Count Register),DX

Flag register

Entire 32 bit

Functionalities of both 8086 and 80386