Fig.15-1 V86 Mode Address Formation

Figure 15-1. V86 Mode Address Formation 19 3 0 +---------------------------------+---------+ BASE | 16-BIT SEGMENT SELECTOR | 0 0 0 0 | +---------------------------------+---------+ + 19 15 0 +---------+---------------------------------+ OFFSET | 0 0 0 0 | 16-BIT EFFECTIVE ADDRESS | +---------+---------------------------------+ = 20 0 LINEAR +---------------------------------------------+ ADDRESS | X X X X X X X X X X X X X X X X X X X X X X | +---------------------------------------------+

Fig.15-2 Entering and Leaving an 8086 Program

Figure 15-2. Entering and Leaving the 8086 Program MODE TRANSITION DIAGRAM +-----------+ TASK SWITCH | INITIAL | +----------------| ENTRY | | OR IRET +-----------+ | v +--------------+ INTERRUPT, EXCEPTION +-------------+ | 8086 PROGRAM |----------------------------->| V86 MONITOR | | (V86 MODE) |<-----------------------------| (PROTECTED | +--------------+ IRET | MODE) | ^ | +-------------+ | | | ^ | | | | | | | | | |TASK SWITCH +-------------------+ TASK SWITCH | | +----------->| OTHER 80386 TASKS |<---------+ | +--------------| (PROTECTED MODE) |-------------+ TASK SWITCH +-------------------+ TASK SWITCH

Fig.15-3 PL 0 Stack after Interrupt in V86 Task

Figure 15-3. PL 0 Stack after Interrupt in V86 Task WITHOUT ERROR CODE WITH ERROR CODE 31 0 31 0 +--------------+<----+ +--------------+<----+ | |OLD GS | | | |OLD GS | | |------+-------| SS:ESP |------+-------| SS:ESP D O | |OLD FS | FROM TSS | |OLD FS | FROM TSS I F |------+-------| |------+-------| R | |OLD DS | | |OLD DS | E E |------+-------| |------+-------| C X | |OLD ES | | |OLD ES | T P |------+-------| |------+-------| I A | |OLD SS | | |OLD SS | O N |--------------| |--------------| N S | OLD ESP | | OLD ESP | I |--------------| |--------------| | O | OLD EFLAGS | | OLD EFLAGS | | N |--------------| |--------------| | | |OLD CS | NEW | |OLD CS | v |--------------| SS:EIP |--------------| | OLD EIP | | | OLD EIP | NEW |--------------|<---+ |--------------| SS:EIP | | | ERROR CODE | | . . |--------------|<---+ . . | | . . . .