assembly.8086.for.beginners.greek

1

Assembly 8086

:

:

Assembly

"8086 Assembler Tutorial for

Beginners"

: 16/01/2013

2

Assembler

( 1)

assembler .

(Basic, C/C++,

Pascal...) .

assembler

emu8086.

(HEX/BIN),

Numbering Systems Tutorial .

assembly;

assembly

.

. :

( )

.

CPU ,

.

3

RAM

.

CPU

8086 CPU 8 ,

.

AX ( AH/AL).

BX ( BH/BL).

CX ( Ch/CL).

DX ( DH/DL).

SI .

DI .

BP .

SP .

,

.

().

16 bit, :

0011000000111001b ( ), 12345

() .

4 (AX, BX, CX, DX)

8 bit , AX=

0011000000111001b, AH=00110000b AL=00111001b.

8 bit

16 bit .

3 , "H" high () "L" low

() .

4

CPU,

.

, .

.

.

,

,

.

CS .

DS .

ES extra ,

.

SS .

, .

-

.

.

12345h (), DS = 1230h

SI = 0045h. ,

16 bit.

CPU 10h (1230h * 10h + 45h = 12345h):

2

. BX, SI DI

DS, BP SP

SS.

. BX

, BH BL !

IP .

Flags Register .

5

IP CS

.

CPU

,

.

.

6

( 2 )

4 : BX, SI, DI, BP.

[] ,

. ():

[BX + SI] [SI] [BX + SI] + d8

[BX + DI] [DI] [BX + DI] + d8

[BP + SI] d16 ( ) [BP + SI] + d8 [BP + DI] [BX] [BP + DI] + d8

[SI] + d8 [BX + SI] + d16 [SI] + d16

[DI] + d8 [BX + DI] + d16 [DI] + d16

[BP] + d8 [BP + SI] + d16 [BP] + d16

[BX] + d8 [BP + DI] + d16 [BX] + d16

d8 8 bit .

d16 16 bit .

. compiler.

[],

compiler .

,

.

compiler d8

d16 .

, DS = 100, BX = 30, SI = 70. [BX + SI] + 25 : 100 * 16 + 30 + 70 + 25 = 1725.

DS

BP, SS. , :

7

. BX BP

. SI PI.

: [BX+5].

(CS, DS, SS, ES)

(segment),

(offset). DS 1234h

SI 7890h 1234:7890.

1234h * 10h + 7890h = 19BD0h.

compiler

:

BYTE PTR byte. WORD PTR ( bytes). :

BYTE PTR [BX] ; byte.

WORD PTR [BX] ; .

MicroAsm : b. BYTE PTR

w. WORD PTR compiler ,

.

MOV

() ().

, .

.

, byte .

8

:

MOV , MOV , MOV , MOV , MOV ,

: AX, BX, CX, DX, AH, AL, BL, BH, CH, CL, DH, DL, DI, SI, BP, SP.

: [BX], [BX+SI+7], , ...

: 5, -24, 3Fh, 10001101b,...

MOV:

MOV . , MOV , . MOV , . MOV . ,

. : DS, ES, SS, : CS.

: AX, BX, CX, DX, AH, AL, BL, BH, CH, CL, DH, DL, DI, SI, BP, SP.

: [BX], [BX+SI+7], , ...

MOV

CS IP.

MOV:

#MAKE_COM# ; o compiler COM file. ORG 100h ; COM. MOV AX, 0B800h ; AX ; B800h. MOV DS, AX ; AX DS. MOV CL, 'A' ; CL ASCII ; 'A', 41h. MOV CH, 01011111b ; CH ; . MOV BX, 15Eh ; BX 15Eh. MOV [BX], CX ; CX, B800:015E RET ; .

9

MicroAsm, [Compile] (

F5 ).

& :

1. ,

.

2. Ctrl + C .

3. MicroAsm

Ctrl + V .

, ; ,

; compiler.

:

( emu8086 microprosessor emulator).

, MOV

.

10

( 3)

.

var1 5A73:235B, 10

.

compiler : BYTE WORD.

:

DB DW

DB Define Byte. DW Define Word.

- , . ( ).

value (, ,

), "?" .

2 ,

MOV

.

MOV:

#MAKE_COM#

ORG 100

MOV AL, var1 MOV BX, var2 RET ; .

VAR1 DB 7

var2 DW 1234h

MicroAsm source editor,

F5 compile.

assemply (emu8086 ).

11

compiler , "VAR1"

"var1" .

VAR1 0108h.

VAR2 0109h, WORD

2 BYTES. low byte

, 34h

12h.

RET,

assembly ,

8086 ( ).

DB:

#MAKE_COM#

ORG 100

DB 0A0h DB 08h DB 01h

DB 8Bh DB 1Eh DB 09h DB 01h

DB 0C3h

DB 7

DB 34h DB 12h

MicroAsm, F5 compile,

(emulator).

.

, compiler

bytes,

, .

ORG 100h compiler ( compiler

).

. compiler

100h (256 bytes),

compiler

.

.

12

100h;

256 bytes CS ( ),

. COM,

EXE 0000,

. EXE

.

. byte , ASCII (0..255).

: a DB 48h, 65h, 6Ch, 6Ch, 6Fh, 00h

b DB Hello, 0

b , compiler , bytes. :

, :

MOV AL, a[3]

BX, SI, DI, BP, :

MOV SI, 3

MOV AL, a[SI]

DUP.

DUP :

DUP ( / )

13

- (

).

DUP .

:

c DB 5 DUP(9)

:

c DB 9, 9, 9, 9, 9

:

d DB 5 DUP(1, 2)

:

d DB 1, 2, 1, 2, 1, 2, 1, 2, 1, 2

, DW DB,

255, -128. DW

.

DUP 1020 ! (

13 ),

( ).

LEA (Load Effective Address)

OFFSET. OFFSET LEA

. LEA

.

,

.

14

:

compiler

:

BYTE PTR byte. WORD PTR ( bytes). :

BYTE PTR [BX] ; byte.

WORD PTR [BX] ; .

MicroAsm : b. BYTE PTR

w. WORD PTR compiler ,

.

:

ORG 100h

MOV AL, VAR1 ; VAR1 AL.

LEA BX, VAR1 ; VAR1 BX.

MOV BYTE PTR [BX], 44h ; VAR1.


RET

VAR1 DB 22h

END

, OFFSET LEA:

ORG 100h


MOV BX, OFFSET VAR1; VAR1 BX.

MOV BYTE PTR [BX], 44h ; VAR1.


RET

VAR1 DB 22h

END

15

.

: LEA BX, VAR1 MOV BX, OFFSET VAR1

compiler : MOV BX, num

num 16 bit offset. ( ): BX, SI, DI, BP! ( ).

, compile (assembled). . EQU :

EQU < >

:

k EQU 5

MOV AX, k

MOV AX, 5

emu8086:

"Variables" "View" emulator.

16

elements .

Assembly ,

.

.

HEX ( 16).

BIN ( 2).

OCT ( 8).

SIGNED ( 10).

UNSIGNED ( 10).

CHAR ASCII ( 256 ,

).

, ,

Edit.

,

"h", "b"

"o", .

: 'hello

world', 0 ( ).

:

1, 2, 3, 4, 5 ( byte words,

BYTE WORD).

, :

:

5 + 2 7 ...

17

( 4)

(interrupts)

.

,

.

(disc drive)

(hardware).

.

hardware,

hardware.

.

INT,

:

0 255 ( 0

0FFh), .

256 ,

. -.

-

AH .

256 ( 256 * 256 =

65536 ). ,

.

.

INT 10h 0h "Hello!".

.

18

#MAKE_COM# ; compiler

;COM file. ORG 100h

- , .

MOV AH, 0Eh ; . INT 10h / 0Eh ASCII AL .

MOV AL, 'H' ; ASCII : 72 INT 10h ; !

MOV AL, 'e'

; ASCII

:101 INT 10h ; !

MOV AL, 'l' ; ASCII : 108 INT 10h ; !

MOV AL, 'l' ; ASCII : 108 INT 10h ; !

MOV AL, 'o' ; ASCII : 111 INT 10h ; !

MOV AL, '!' ; ASCII : 33 INT 10h ; !

RET ; .

, compile. !

list of basic interrupts .

19

( 5)

emu8086.inc

.

INCLUDE

. compiler

,

Inc.

emu8086.inc ( Inc),

,

.

emu8086.inc

:

include 'emu8086.inc'

emu8086.inc (macros): PUTC char 1 , ASCII

. GOTOXY col, row 2 ,

. PRINT string 1 ,

. PRINTN string 1 ,

. PRINT .

CURSOROFF . CURSORON .

:

20

include emu8086.inc

ORG 100h

PRINT 'Hello World!'

GOTOXY 10, 5

PUTC 65 ; 65 - ASCII 'A' PUTC 'B'

RET ; . END ; compiler.

compiler

emu8086.inc

. ,

,

(

).

emu8086.inc :

PRINT_STRING , DS:SI. : DEFINE_PRINT_STRING END.

PTHIS - , ( PRINT_STRING), . CALL. :

CALL PTHIS db 'Hello World!', 0

: DEFINE_PTHIS END.

GET_STRING -

.

DS:DI, DX.

'Enter'.

: DEFINE_GET_STRING END.

CLEAR_SCREEN , ( ), . : DEFINE_CLEAR_SCREEN END.

21

SCAN_NUM CX. : DEFINE_SCAN_NUM END.

PRINT_NUM AX. : DEFINE_PRINT_NUM DEFINE_PRINT_NUM_UNS END.

PRINT_NUM_UNS AX. : DEFINE_PRINT_NUM_UNS END.

( END), CALL .

:

include 'emu8086.inc' ORG 100h

LEA SI, msg1 ; CALL print_string CALL scan_num ; CX.

MOV AX, CX ; ; AX.

; string: CALL pthis DB 13, 10, 'You have entered: ', 0

CALL print_num ; ; AX.

RET ; .

msg1 DB 'Enter the number: ', 0

DEFINE_SCAN_NUM DEFINE_PRINT_STRING DEFINE_PRINT_NUM DEFINE_PRINT_NUM_UNS ; print_num. DEFINE_PTHIS END ; compiler.

22

compiler ( ). compiler CALL . CALL . , 100 , . , ; , , .

23

( 6)

( ) .

16bit . bit 0 1 . (CF) - 1 ,

. , bytes 255+1 ( 0...255) . 0 .

(ZF) - 1 0 . 0 .

(SF) - 1 . , 0 . , (MSB) .

(OF) - 1 . , bytes 100+50 ( -128...127)

(PF) - 1 0 . , 8 bit .

(AF) - 1 (4 bits) .

(IF) - 1 , .

(DF) - . 0 - , 1 .

24

3 .

: ADD, SUB,CMP, AND, TEST, OR, XOR

:

REG(), memory( ) memory, REG REG, REG memory, immediate( ) REG, immediate

REG: AX, BX, CX, DX, AH, AL, BL, BH, CH, CL, DH, DL, DI, SI, BP, SP. memory: [BX], [BX+SI+7], , ... immediate: 5, -24, 3Fh, 10001101b, ...

, . CMP TEST . :

CF, ZF, SF, OF, PF, AF.

ADD - . SUB - . CMP - ( ). AND - 2 .

:

1 AND 1 = 1 1 AND 0 = 0 0 AND 1 = 0 0 AND 0 = 0

1 , 2 bit 1 .

TEST - AND .

OR - 2 .

: 1 OR 1 = 1 1 OR 0 = 1 0 OR 1 = 1 0 OR 0 = 0

1 , 1() bit .

25

XOR - XOR ( ) 2 .

: 1 XOR 1 = 0 1 XOR 0 = 1 0 XOR 1 = 1 0 XOR 0 = 0

1 bit .

: MUL, IMUL, DIV, IDIV :

REG memory

REG: AX, BX, CX, DX, AH, AL, BL, BH, CH, CL, DH, DL, DI, SI, BP, SP.

memory: [BX], [BX+SI+7], , ...

MUL IMUL :

CF, OF

1 . , 0 .

DIV IDIV .

MUL - :

byte: AX = AL * .

word(): (DX AX) = AX * .

IMUL - :

byte: AX = AL * . word: (DX AX) = AX * .

DIV - :

26

byte: AL = AX /

AH = .

word:

AX = (DX AX) /

DX = .

IDIV - :

byte: AL = AX /

AH = .

word: AX = (DX AX) /

DX = .

: INC, DEC, NOT, NEG

:

REG memory

REG: AX, BX, CX, DX, AH, AL, BL, BH, CH, CL, DH, DL, DI, SI, BP, SP.

memory: [BX], [BX+SI+7], , ...

INC , DEC :

ZF, SF, OF, PF, AF.

NOT !

NEG :

CF, ZF, SF, OF, PF, AF.

NOT - bit .

NEG - ( 2) . bit 1 . , 5 -5 -2 2 .

27

( 7)

. , .

JMP . JMP :

JMP

, ":" . , . , 3 :

label1: label2: a:

. :

x1: MOV AX, 1 x2: MOV AX, 2

JMP:

ORG 100h

MOV AX, 5 ; AX 5. MOV BX, 2 ; BX 2.

JMP calc ; 'calc'.

back: JMP stop ; 'stop'.

calc: ADD AX, BX ; BX AX. JMP back ; 'back'.

stop:

RET ; .

END ; compiler .

28

, 2 , JMP .

, JMP , . (65 , 535 bytes) .

JMP , ( , ) . 3 . . , , .

JZ , JE . ZF = 1 JNZ, JNE

JS . SF = 1 JNS

JO OF = 1 JNO . JPE, JP . PF = 1 JPO JNZ , JNE . ZF = 0 JZ, JE

JNS . SF = 0 JS JNO OF = 0 JO . JPO, JNP . PF = 0 JPE, JP

, , , JE - :JZ .

, , .

JC , JB, JNAE .

CF = 1 JNC, JNB, JAE

JNC , JNB,

JAE

.

CF = 0 JC, JB, JNAE

29

JL , JNGE .

- () .

ZF = 1

ZF = 0

ZF = 0

and

SF = OF

SF OF

SF = OF

ZF = 1

or

SF OF

JNE, JNZ

JE, JZ JNG, JLE

JNL, JGE

JNGE, JL JNLE, JG

JE , JZ (=) 0 .

JNE , JNZ () 0 .

JG , JNLE ( .

JGE , JNL .

JLE , JNG .

30

JA , JNBE . .

.

JAE , JNB, JNC .

, CMP ( SUB() , , ) .

. : 5 2 , 5-2=3 ( 0) . : 7 7 , 7-7=0

ZF = 1

ZF = 0

CF = 0

and

ZF = 0 CF = 1 CF = 0

CF = 1

or

ZF = 1

JNE, JNZ

JE, JZ JNA, JBE JNB, JAE, JNC JNAE, JB

JNBE, JA

JE , JZ (=) 0 .

JNE , JNZ () 0 .

JB , JNAE, JC

JBE , JNA .

31

! ( 1 JZ JE ) .

CMP :

include emu8086.inc

ORG 100h

MOV AL, 25 ; AL 25. MOV BL, 10 ; BL 10.

CMP AL, BL ; AL - BL.

JE equal ; AL = BL (ZF = 1).

PUTC 'N' ; , AL BL, JMP stop ; '' stop.

equal: ; , PUTC 'Y' ; AL = BL, 'Y'.

stop:

RET ; , . END

AL BL , , click [FLAGS] . [Single Step] . , ( F5).

. CMP 127 bytes 128 bytes ( 3 bytes) .

:

o _x . o JMP . o _x: JMP .

_x: - .

32

:

include emu8086.inc

ORG 100h

MOV AL, 25 ; AL 25. MOV BL, 10 ; BL 10.

CMP AL, BL ; AL - BL.

JNE not_equal ; if AL BL (ZF = 0). JMP equal

not_equal: ; ; ; 127 bytes... PUTC 'N' ; , AL BL, JMP stop ; 'N', stop.

equal: ; , PUTC 'Y' ; AL = BL, 'Y'.

stop:

RET ; , .

END

, , . "$" , , . :

ORG 100h

; : ; 2 byte, JMP $2

a DB 3 ; 1 byte. b DB 4 ; 1 byte.

; JCC 7 bytes: ; (JMP 2 byte ) MOV BL,9

DEC BL ; 2 bytes. CMP BL, 0 ; 3 bytes. JNE $-7

RET END

33

( 8)

, . . , .

:

PROC

; ; ...

RET ENDP

- . , . . , RET . . ( , ) . PROC ENDP , . . CALL . :

ORG 100h

CALL m1

MOV AX, 2

RET ; .

m1 PROC MOV BX, 5 RET ; . m1 ENDP

END

m1 , MOV BX, 5 CALL MOV AX, 2.

34

. , . 2 AL BL , AX:

ORG 100h

MOV AL, 1 MOV BL, 2

CALL m2 CALL m2 CALL m2 CALL m2

RET ; .

m2 PROC MUL BL ; AX = AL * BL. RET ; . m2 ENDP

END

AL . BL . 2 4 , AX 16 ( 10h)

, "Hello World!":

ORG 100h LEA SI, msg ; SI msg . CALL print_me

RET ; .

; ========================================================== ; . ; 0 , ; SI: print_me PROC

next_char: CMP b.[SI], 0 ; 0 . JE stop ;

MOV AL, [SI] ; ASCII .

MOV AH, 0Eh ; . INT 10h ; AL . ADD SI, 1 ; .

35

JMP next_char ; .

stop: RET ; . print_me ENDP ; ==========================================================

msg DB 'Hello World!', 0 ; .

END

"b." - [SI] 2bytes . "w." . , .

36

( 9)

. CALL . RET . INT . . IRET . . : PUSH - 16byte . POP - 16byte .

PUSH:

PUSH REG PUSH SREG PUSH memory PUSH immediate

REG: AX, BX, CX, DX, DI, SI, BP, SP. SREG: DS, ES, SS, CS. memory: [BX], [BX+SI+7], 16 bit , ... immediate: 5, -24, 3Fh, 10001101b, ...

POP:

POP REG POP SREG POP memory

REG: AX, BX, CX, DX, DI, SI, BP, SP.

SREG: DS, ES, SS, ( CS). memory: [BX], [BX+SI+7], 16 bit , ...

PUSH POP 16byte! : PUSH 80186 !

LIFO ( ) . PUSH :

37

1, 2, 3, 4, 5

5, 4, 3, 2, 1.

PUSH POP , , ( 0000h) .

PUSH POP . :

( PUSH) . . ( POP) .

:

ORG 100h

MOV AX, 1234h PUSH AX ; AX .

MOV AX, 5678h ; AX .

POP AX ; AX AX .

RET

END

38

. :

ORG 100h

MOV AX, 1212h ; 1212h AX . MOV BX, 3434h ; 3434h BX .

PUSH AX ; AX . PUSH BX ; BX .

POP AX ; AX . POP BX ; BX .

RET

END

LIFO , PUSH 1212h 3434h , POP 3434h 1212h .

SS( ) SP( ) . .

"PUSH " :

2 SP .

SS:SP .

"POP " :

SS:SP .

2 SP .

SS:SP . COM , 0FFFEh . SS:0FFFEh RET . emu8086 click [Stack] . "

39

( 10)

, . , . . , . Emu8086.inc . . :

MACRO [,...]

ENDM

, . :

MyMacro MACRO p1, p2, p3

MOV AX, p1 MOV BX, p2 MOV CX, p3

ENDM

ORG 100h

MyMacro 1, 2, 3

MyMacro 4, 5, DX

RET

:

MOV AX, 00001h MOV BX, 00002h MOV CX, 00003h MOV AX, 00004h MOV BX, 00005h MOV CX, DX

40

:

CALL . :

CALL MyProc

. :

MyMacro

100 , . RET . . CALL 3byte , , .

. 100 , 100 , , .

.

, . :

MyMacro 1, 2, 3

ENDM .

, ENDP .

, " " 2 . , LOCAL , . :

MyMacro2 MACRO

LOCAL label1, label2

CMP AX, 2 JE label1 CMP AX, 3

JE label2

41

label1:

INC AX

label2:

ADD AX, 2

ENDM ORG 100h

MyMacro2

MyMacro2

RET

, . Inc INCLUDE file-name . - emu8086.inc

assembly.8086.for.beginners.greek

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