Chapter 1 lab task: Compile the program for handling the No. 0 interruption

Question: Compile the handling of No. 0 interruptionsProgramTo display the string "Divide Error!" in the middle of the screen when division overflow occurs !", Then return to DoS

Requirement: Follow up debugging carefully.

Source code:

Assume Cs: codesg </P> <p> codesg segment <br/> Start: <br/>; Set DS: [Si] points to the <SPAN class = 'wp _ keywordlink '> Code </span> <br/> mov ax, CS <br/> mov ds, ax <br/> mov Si, offset do0; offset do0 is the offset address from program start to do0 to Si </P> <p> mov ax, 0000 <br/> mov es, ax <br/> mov Di, 0200 h; Set ES: [di] points to the target location of the program to be copied </P> <p> mov CX, offset do0end-offset do0; sets the number of replication cycles, here, the number of cycles is to copy the start address of the program to the end address of the Program </P> <p> CLD; set Si and Di to increase by 1 </P> <p> rep movsb; to replicate the cycle Process </P> <p>; set the interrupt vector table. Because the number N is interrupted, the segment address is placed in the unit 0000: [N * 4, the offset address is placed in the cell 0000: [N * 4 + 2. Therefore, the segment address of the program to be interrupted is placed in the unit of 0000: [N * 4], and the offset address is set to 0000: [N * 4 + 2. <Br/> mov word ptr es: [0*4], 200 h <br/> mov word ptr es: [0*4 + 2], 0000 </P> <p>; here is the written test program. Of course, it can also be written and executed during debug <br/>; MoV ax, 1000 h <br/>; moV BH, 1 <br/>; Div BH </P> <p> mov ax, 4c00h <br/> int 21 h </P> <p>; here is the Interrupt Processing Program <br/> do0: <br/>. At the beginning, it is a string that defines the output and cannot be executed, therefore, the system jumps to do0start and runs <br/> JMP short do0start <br/> db'divide error! '</P> <p> do0start: <br/> mov ax and CS <br/> mov DS and ax <br/> mov Si, 0202 h; Set DS: [Si] points to the defined string 'divide error! '</P> <p> mov ax, 0b800h <br/> mov es, ax <br/> mov Di, 12*160 + 36*2; Set ES: [di] pointing to the center of the screen </P> <p> mov CX, 13; set the number of cycles for displaying strings </P> <p> S: <br/> mov Al, DS: [Si] <br/> mov ah, 02 h; set the displayed font color <br/> mov ES: [di], ax <br/> Add Di, 2 <br/> Inc Si <br/> loop S </P> <p> mov ax, 4c00h <br/> int 21 h <br/> do0end: <br/> NOP <br/> codesg ends <br/> end start </P> <p>

debugging process:

-R </P> <p> AX = 0000 BX = 0000 Cx = 005c dx = 0000 sp = 0000 BP = 0000 Si = 0000 di = 0000 <br/> DS = 0b75 es = 0b75 Ss = 0b85 cs = 0b85 IP = 0000 NV up ei pl nz Na Po NC <br/> 0b85: 0000 8cc8 movax, CS <br/>-u </P> <p> 0b85: 0000 8cc8 movax, CS <br/> 0b85: 0002 8ed8 movds, ax <br/> 0b85: 0004 be2800 movsi, 0028 <br/> 0b85: 0007 b80000 movax, 0000 <br/> 0b85: 000a 8ec0 moves, ax <br/> 0b85: 000c bf0002 movdi, 0200 <br/> 0b85: 000f b93300 movcx, 0033 <br /> 0b85: 0012 fc cld <br/> 0b85: 0013 F3 repz <br/> 0b85: 0014 A4 movsb <br/> 0b85: 0015 26 ES: <br/> 0b85: 0016 c70600000002 movword PTR [0000], 0200 <br/> 0b85: 001c 26 ES: <br/> 0b85: 001d c70602000000 movword PTR [0002], 0000 <br/>-T </P> <p> AX = 0b85 BX = 0000 Cx = 005c dx = 0000 sp = 0000 BP = 0000 Si = 0000 di = 0000 <br /> DS = 0b75 es = 0b75 Ss = 0b85 cs = 0b85 IP = 0002 NV up ei pl nz Na Po NC <br/> 0b85: 0002 8ed8 movds, ax <br/>-T </ P> <p> AX = 0b85 BX = 0000 Cx = 005c dx = 0000 sp = 0000 BP = 0000 Si = 0000 di = 0000 <br/> DS = 0b85 es = 0b75 SS = 0b85 cs = 0b85 IP = 0004 NV up ei pl nz Na Po NC <br/> 0b85: 0004 be2800 movsi, 0028 <br/>-T </P> <p> AX = 0b85 BX = 0000 Cx = 005c dx = 0000 sp = 0000 BP = 0000 Si = 0028 di = 0000 <br /> DS = 0b85 es = 0b75 Ss = 0b85 cs = 0b85 IP = 0007 NV up ei pl nz Na Po NC <br/> 0b85: 0007 b80000 movax, 0000 <br/>-T </P> <p> AX = 0000 BX = 0000 Cx = 005c dx = 0000 sp = 0000 BP = 0000 Si = 0028 di = 0000 <br/> DS = 0b85 es = 0b75 Ss = 0b85 cs = 0b85 IP = 000a NV up ei pl nz Na Po NC <br/> 0b85: 000a 8ec0 moves, ax <br/>-T </P> <p> AX = 0000 BX = 0000 Cx = 005c dx = 0000 sp = 0000 BP = 0000 Si = 0028 di = 0000 <br /> DS = 0b85 es = 0000 Ss = 0b85 cs = 0b85 IP = 000c NV up ei pl nz Na Po NC <br/> 0b85: 000c bf0002 movdi, 0200 <br/>-T </P> <p> AX = 0000 BX = 0000 Cx = 005c dx = 0000 sp = 0000 BP = 0000 Si = 0028 di = 0200 <br /> DS = 0b85 es = 0000 Ss = 0b85 cs = 0b85 IP = 000f NV up ei pl nz Na Po NC <br/> 0b85: 000f b93300 movcx, 0033 <br/>-T </P> <p> AX = 0000 BX = 0000 Cx = 0033 dx = 0000 sp = 0000 BP = 0000 Si = 0028 di = 0200 <br /> DS = 0b85 es = 0000 Ss = 0b85 cs = 0b85 IP = 0012 NV up ei pl nz Na Po NC <br/> 0b85: 0012 fc cld <br/>-T </P> <p> AX = 0000 BX = 0000 Cx = 0033 dx = 0000 sp = 0000 BP = 0000 Si = 0028 di = 0200 <br/> DS = 0b85 es = 0000 Ss = 0b85 cs = 0b85 IP = 0013 NV up ei pl nz Na Po NC <br/> 0b85: 0013 F3 repz <br/> 0b85: 0014 A4 movsb <br/>-P </P> <p> AX = 0000 BX = 0000 Cx = 0000 dx = 0000 sp = 0000 BP = 0000 Si = 005b di = 0233 <br/> DS = 0b85 es = 0000 Ss = 0b85 cs = 0b85 IP = 0015 NV up ei pl nz Na Po NC <br/> 0b85: 0015 26 ES: <br/> 0b85: 0016 c7060042602 movword PTR [0000], 0200 ES: 0000 = 1068 <br/>-T </P> <p> AX = 0000 BX = 0000 Cx = 0000 dx = 0000 sp = 0000 BP = 0000 Si = 005b di = 0233 <br/> DS = 0b85 es = 0000 Ss = 0b85 cs = 0b85 I P = 001c NV up ei pl nz Na Po NC <br/> 0b85: 001c 26 ES: <br/> 0b85: 001d c70602000000 movword PTR [0002], 0000 ES: 0002 = 00a7 <br/>-T </P> <p> AX = 0000 BX = 0000 Cx = 0000 dx = 0000 sp = 0000 BP = 0000 Si = 005b di = 0233 <br/> DS = 0b85 es = 0000 Ss = 0b85 cs = 0b85 IP = 0023 NV up ei pl nz Na Po NC <br/> 0b85: 0023 b8004c movax, 4c00 <br/>-T </P> <p> AX = 4c00 BX = 0000 Cx = 0000 dx = 0000 sp = 0000 BP = 0000 Si = 005b di = 0233 <br /> DS = 0b85 es = 0000 Ss = 0b85 cs = 0b85 IP = 0026 NV up ei pl nz Na Po NC <br/> 0b85: 0026 cd21 int21 <br/>-D :0200 </P> <p> :0200 EB 0d 44 49 56 49 44 45-20 45 52 52 4f 52 21 8C .. divide Error !. <Br/> :0210 C8 8e D8 be 02 B8 00-b8 8e C0 BF C8 07 B9 0d ................ <br/> running :0220 00 8A 04 B4 02 26 89 05-83 C7 02 46 E2 F3 B8 00 ..... &..... F .... <br/> 4C CD 21 00 00 00 00 00-00 00 00 00 00 00 00 00 00 00 00 l .!............. <Br/> Jun :0240 00 00 00 00 00 00 00-00 00 00 00 00 00 00 00 ................ <br/> Jun :0250 00 00 00 00 00 00 00-00 00 00 00 00 00 00 00 ................ <br/> 0000: 0260 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ <br/> 0000: 0270 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ <br/>-T

Test procedure:

Then write the following command in debug and execute

MoV ax, 1000 h <br/> mov BH, 1 <br/> Div BH