1. 4.4 Bit Manipulation Instructions
Shift instructions: SHL/SAL, SHR, SAR
Examples: initial value in AX= B
CF=0
SAL AX,1
AX= B
lost
AX= B
SAR AX,4
CF=0
Shift instructions: SHLD, SHRD
Examples: CX=0BC3H; AX= 5678H
SHRD AX,CX,4
CF=1
CX=0BC3H; AX= 3567H
unchanged

2. 4.4 Bit Manipulation Instructions
Rotate instructions: ROL, ROR, RCL, RCR
Examples: initial value in AX= B
CF=0
ROL AX,1
AX= B
AX= B
ROR AX,4
CF=0
Examples: initial value in AX= B and CF=1
RCL AX,1
AX= B CF= 0
AX= B CF=0
RCR AX,4

3. 4.5 Program Transfer Instructions
JMP
Short jump address is computed adding the signed byte operand to the address of the first byte following the JMP instruction.
LOOP, LOOPE/LOOPZ, LOOPNE/LOOPNZ
JCXZ, JECXZ

4. 4.5 Program Transfer Instructions
Jcc
The terms “less” and “greater” are used for comparisons of signed integers.
The terms “above” and “below” are used for comparisons of unsigned integers.

5. 4.5 Program Transfer Instructions
CALL …
0100 CALL EXSUB
0103 ADD AX, 1
0204 CALL EXSUB
0207 ADD AX,2
RET …
0500 EXSUB PROC NEAR
...
0550 RET
EXSUB ENDP
Assembler directives specifying the begin and the end of a NEAR or FAR procedure (subroutine)
Stack:
1FFE ??
1FFF ??
2000 ??
Stack:
1FFE 07
1FFF 02
2000 ??
Stack:
1FFE 03
1FFF 01
2000 ??
SP
SP
SP
SP
SP

6. 4.5 Program Transfer Instructions
INT …
0000: B4
0000:
0000:
0000:
IPT= Interrupt Pointer Table
4*21H=84H
IRET,IRETD …
0100:00FF MOV AH, 2CH;
0100: INT 21H
0100: ADD AX, 1 …
0726:16B4 ISR for INT 21
...
… IRET
INTO,BOUND
Stack:
1FFA ??
1FFB ??
1FFC ??
1FFD ??
1FFE ??
1FFF ??
2000 ??
Stack:
1FFA 03
1FFB 01
1FFC 00
1FFD 01
1FFE 08
1FFF 41
2000 ??
SP
SP
SP
FLAGS=4108H

7. 4.5 Program Transfer Instructions
ENTER, LEAVE
ENTER 6,0 …
00F8 ??
00F9 ??
00FA ??
00FB ??
00FC ??
00FD ??
00FE ??
00FF ??
0100 ?? …
00F8 ??
00F9 ??
00FA ??
00FB ??
00FC ??
00FD ??
00FE 34
00FF 12
0100 ??
SP
SP
BP
SP
If Level=0, BP is saved on stack,
BP is loaded with the content of SP,
Reserved memory space
SP is decremented by Space16.
BP old value =1234H
SP old value =0100H
BP new value =00FEH
SP intermediate value =00FEH
SP final value =00F8H
LEAVE
SP is loaded with the content of BP,
BP is popped from stack.=>
values before ENTER restored.
Stack Frame
Frame pointer
SP back to old value =0100H
BP back to old value =1234H

8. 4.6 Processor Control Instructions