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