【Comprehensive assembly programming design】—— Microcomputer principle experiment

1. Experimental requirements

1. Calculate S=1+2×3+3×4+4×5+…+N(N+1) until N(N+1) is greater than 200 .

analyse as below:

• Construct a loop structure, S = 1 + 2×3 + 3×4 + 4×5 + … + N (N + 1), accumulate and judge item by item until N (N + 1) items are greater than 200, use LOOP loop instruction and compare integer instruction CMP;
• The calculation result shows that the hexadecimal value in the register is converted into decimal and displayed on the virtual terminal interface. The instructions used include the transfer instruction MOV, the integer comparison instruction CMP, the unconditional transfer instruction JMP, the division instruction DIV, and the push operation instruction PUSH, The pop-up operation instruction POP, the addition instruction ADD and the function INT 21H instruction which outputs a character.

2. Seek N! . N is a positive integer not greater than 8 entered by the keyboard.

analyse as below:

• Inputting a positive integer not greater than 8 from the keyboard needs to be realized by using the INT 21H command called by the DOS function, and judging whether the input value meets the requirements of the topic, and giving an abnormal display reminder;
• Construct a loop, N! = 1 × 2 × … × (N - 1) × N, N is the value input from the keyboard, the register is stored in hexadecimal, use the LOOP cycle instruction and the comparison integer instruction CMP, during the calculation process Pay attention to distinguish the input value as decimal, and the computer recognizes it as the corresponding ASCII code;
• The display function is designed in two parts. The first part is character string display, which is generally implemented by calling the INT 21H command of the DOS function. The other part is to convert the hexadecimal value in the register into decimal and display it on the virtual terminal interface.

3. Input a line of characters from the keyboard (terminated by carriage return), and count by letters, numbers and other characters, and finally display the 3 counting results.

analyse as below:

• For the ultimate use of branches, compare ASCII codes from small to large;
• Use three variables to record the number of user input numbers, letters and other types. Determine the type according to the ASCII code, and call the decimal number output subroutine dispdec after traversing the entire sentence to output the statistical number program;
• Define the buffer: store the sentences entered by the user, use digit, letter, and other to represent the number of numbers, letters, and other characters counted, and initialize them to 0. Use bx to point to the first address of the sentence entered by the user, and then judge if it is 30H~39H, then digit will be incremented, or if it is 41H~5AHor 61H~7AH, then letter will be incremented, otherwise other will be incremented, then bx will be incremented, and the judgment will be repeated continuously. The number of loops is the length of the sentence, which is the previous cx = The length of the sentence entered by the user. Finally output the result.

4. Write an electronic clock program and display it in the middle of the screen in the following format:
   YYYYYYYYYMMDDDDHH
   :MM:SS

analyse as below:

• Call the DOS operating system module 10, input the format of the time, and place the input time in the defined memory buffer in the form of a character string, and then call the subroutine, store the ASCII code in the memory buffer, and place the value of the hour, minute, and second in register;
• Call the subroutine with a delay of 1s, add it to the register storing the second value, and convert it to decimal. During the accumulation process, the hours, minutes, and seconds are continuously compared. The seconds and minutes cannot be equal to 60, and every 60 is set to zero and then displayed on the virtual terminal;
• Call the INT 21H instruction of DOS function to realize virtual terminal display.

2. The purpose of the experiment

• Integrating various assembly programming methods, master the writing of more complex assembly application programs with human-computer interaction interface.

3. Experimental code and experimental results

Experiment 1

(1) Experiment code:

DATA SEGMENT
    STRING1 DB 'S= $'
DATA ENDS
CODE SEGMENT
START:
    MOV AX,DATA
    MOV DS,AX
    MOV AX,2 
    MOV BX,AX
    INC BX 
    MOV CX,15 
    MOV DX,1 
FOR:
    IMUL BL
    CMP AL,200
    JA OUTSIDE
    ADD DX,AX
    MOV AX,DX
    MOV AX,BX
    INC BX
LOOP FOR
OUTSIDE: 
    MOV AX,DX
    PUSH AX
    LEA DX,STRING1
    MOV AH,09H
    INT 21H
    POP AX
    CALL PRINT
    MOV AX, 4C00H 
    INT 21H
CRLF:
    PUSH AX
    PUSH DX
    MOV DL,0AH
    MOV AH,2H
    INT 21H
    MOV DL,0DH
    MOV AH,2H
    INT 21H
    POP DX
    POP AX
    RET
PRINT:
    PUSH AX
    MOV CX,0
    MOV BX,10
DISP1:
    MOV DX,0
    DIV BX 
    PUSH DX
    INC CX
    OR AX,AX
    JNE DISP1
DISP2:
    MOV AH,2
    POP DX
    ADD DL, 30H
    INT 21H
LOOP DISP2
    POP AX
    RET
CODE ENDS
END START

(2) Experimental results:

Experiment 2

(1) Experiment code:

DATA SEGMENT
  STRING0 DB 'PLEASE INPUT A NUMBER: $'
  STRING1 DB 'INLEGAL CHARACTER! $'
  STRING2 DB 'RESULT OF N! = $'
DATA ENDS

CODE SEGMENT
    ASSUME CS:CODE,DS:DATA
    START:
        MOV AX,DATA
        MOV DS,AX
        LEA DX,STRING0
        MOV AH,09H
        INT 21H
        MOV AH,01H 
        INT 21H
        CALL CRLF
        CMP AL,38H 
        JA INLEGAL
        CMP AL,30H 
        JB INLEGAL
        JE PART01
        CMP AL,31H
        JE PART01
        SUB AL,30H
        MOV CX,0
        MOV CL,AL
        DEC CL     
        MOV AX,1
        MOV BX,2
        MOV DX,0  
    MUL:
        IMUL BX
        MOV DX,AX
        INC BX
    LOOP MUL
        PUSH DX   
        LEA DX,STRING2
        MOV AH,09H
        INT 21H
        POP AX
        CALL PRINT
    TAIL:
        MOV AX, 4C00H
        INT 21H
    PART01:
        LEA DX,STRING2
        MOV AH,09H
        INT 21H
        MOV AX,1
        CALL PRINT
        JMP TAIL
    INLEGAL:
        LEA DX,STRING1 
        MOV AH,09H
        INT 21H
        JMP TAIL
    PRINT:
        PUSH AX
        MOV CX,0
        MOV BX,10
    DISP1:
        MOV DX,0
        DIV BX
        PUSH DX
        INC CX
        OR AX,AX
        JNE DISP1
    DISP2:
        MOV AH,2
        POP DX
        ADD DL,30H
        INT 21H
    LOOP DISP2
        POP AX
        RET
    CRLF:
        PUSH AX
        PUSH DX
        MOV DL,0AH
        MOV AH,2H
        INT 21H
        MOV DL,0DH
        MOV AH,2H
        INT 21H
        POP DX
        POP AX
        RET
ENDS
END START

(2) Experimental results:

Experiment 3

(1) Experiment code:

DATA SEGMENT
    STRING0 DB 'PLEASE INPUT A STRING: $'
    STRING1 DB 'NUMBER OF ALPHABET: $'
    STRING2 DB 'NUMBER OF NUMBER: $'
    STRING3 DB 'NUMBER OF OTHER CHARACTER: $'
    NUM_ALPH DB 0
    NUM_NUM DB 0
    NUM_CHAR DB 0
ENDS

CODE SEGMENT
    ASSUME CS:CODE,DS:DATA
START:
    MOV AX, DATA
    MOV DS, AX
    LEA SI,NUM_ALPH
    LEA DX,STRING0 
    MOV AH,09H
    INT 21H
    MOV CX,40
INPUT:
    MOV AH,01H
    INT 21H
    CMP AL,0DH 
    JE PRINTF_NUM
    CMP AL,48
    JB ADD_CHAR
    CMP AL,58  
    JB ADD_NUM
    CMP AL,65
    JB ADD_CHAR
    CMP AL,91
    JB ADD_ALPH
    CMP AL,97
    JB ADD_CHAR
    CMP AL,123
    JB ADD_ALPH
    JMP ADD_CHAR
INSIDE:
LOOP INPUT
PRINTF_NUM:
    CALL CRLF
    CALL CRLF
    LEA DX,STRING1 
    MOV AH,09H
    INT 21H
    MOV AL,[SI]
    MOV AH,0
    CALL PRINT
    CALL CRLF
    CALL CRLF
    LEA DX,STRING2 
    MOV AH,09H
    INT 21H
    MOV AL,[SI+1]
    MOV AH,0
    CALL PRINT
    CALL CRLF
    CALL CRLF
    LEA DX,STRING3 
    MOV AH,09H
    INT 21H
    MOV AL,[SI+2]
    MOV AH,0
    CALL PRINT
TAIL:
    MOV AX, 4C00H
    INT 21H
CRLF:
    PUSH AX
    PUSH DX
    MOV DL,0AH
    MOV AH,2H
    INT 21H
    MOV DL,0DH
    MOV AH,2H
    INT 21H
    POP DX
    POP AX
    RET
PRINT:
    PUSH AX
    MOV CX,0 
    MOV BX,10
DISP1:
    MOV DX,0
    DIV BX
    PUSH DX
    INC CX
    OR AX,AX
    JNE DISP1
DISP2:
    MOV AH,2
    POP  DX 
    ADD  DL, 30H
    INT 21H
LOOP DISP2 
    POP AX
    RET
ADD_ALPH:
    PUSH DX
    MOV DL,[SI]
    INC DL
    MOV [SI],DL
    POP DX
    JMP INSIDE
ADD_NUM:
    PUSH DX
    MOV DL,[SI+1]
    INC DL
    MOV [SI+1],DL
    POP DX
    JMP INSIDE
ADD_CHAR:  
    PUSH DX
    MOV DL,[SI+2]
    INC DL
    MOV [SI+2],DL
    POP DX
    JMP INSIDE
ENDS
END START 

(2) Experimental results:

Experiment 4

(1) Experiment code:

DATA SEGMENT
    YEAR DW 0
    MONTH DB 0
    DAY DB 0
    HOUR DB 0
    MINUTE DB 0
    SECOND DB 0
    DATE DB '0000YEAR00MONTH00DAY$'
    TIME DB '00:00:00$'
    LEN EQU $-TIME
    LEN EQU $-DATE
    NUM DB 10
    DATA ENDS
STACK SEGMENT
    DW 128 DUP(0)
    STACK ENDS
CODE SEGMENT
    ASSUME CS:CODE,DS:DATA,SS:STACK
START:  MOV AX,DATA
        MOV DS,AX
        MOV ES,AX
BEGIN:  CALL SETSHOW
        CALL GET_SYSTEM_DATE
        CALL SETSHOW1
        CALL GET_SYSTEM_TIME
        JMP BEGIN ;无线循环，不停获取到新的系统时间
    GET_SYSTEM_DATE PROC ;获取系统日期
        MOV AH,2AH
        INT 21H 
        MOV YEAR,CX
        MOV MONTH,DH
        MOV DAY,DL
        MOV AX,0
        MOV BX,0
        MOV AX,YEAR
        MOV BL,100
        DIV BL
        MOV BH,AH
        MOV AH,0
        DIV NUM
        ADD AL,30H
        MOV DATE[0],AL
        ADD AH,30H
        MOV DATE[1],AH
        MOV AX,0
        MOV AL,BH
        DIV NUM
        ADD AL,30H
        MOV DATE[2],AL
        ADD AH,30H
        MOV DATE[3],AH
        MOV AX,0
        MOV AL,MONTH
        DIV NUM
        ADD AL,30H
        MOV DATE[8],AL
        ADD AH,30H
        MOV DATE[9],AH
        MOV AX,0
        MOV AL,DAY
        DIV NUM
        ADD AL,30H
        MOV DATE[15],AL
        ADD AH,30H
        MOV DATE[16],AH
        LEA DX,DATE
        MOV AH,9
        INT 21H
        RET
        GET_SYSTEM_DATE ENDP
    GET_SYSTEM_TIME PROC  ;获取系统时间
        MOV AH,2CH
        INT 21H
        MOV HOUR,CH
        MOV MINUTE,CL
        MOV SECOND,DH
        MOV AX,0
        MOV AL,HOUR
        DIV NUM
        ADD AL,30H
        MOV TIME[0],AL
        ADD AH,30H
        MOV TIME[1],AH
        MOV AX,0
        MOV AL,MINUTE
        DIV NUM
        ADD AL,30H
        MOV TIME[3],AL
        ADD AH,30H
        MOV TIME[4],AH
        MOV AX,0
        MOV AL,SECOND
        DIV NUM
        ADD AL,30H
        MOV TIME[6],AL
        ADD AH,30H
        MOV TIME[7],AH
        LEA DX,TIME
        MOV AH,9
        INT 21H
        RET
        GET_SYSTEM_TIME ENDP
    SETSHOW PROC   ;设置光标位置
        MOV DH,12   ;行号
        MOV DL,29   ;列号
        MOV BH,0
        MOV AH,2
        INT 10H
        RET
        SETSHOW ENDP
    SETSHOW1 PROC ;设置光标位置
        MOV DH,13   
        MOV DL,35   
        MOV BH,0
        MOV AH,2
        INT 10H
        RET
        SETSHOW1 ENDP
        MOV AX,4CH
        INT 21H
CODE ENDS
END START

(2) Experimental results:

4. Experimental summary

Through this experiment, I learned about the operation of interacting with the system, became more familiar with the design and application of assembly programs such as sequential structures, loop structures, branch jump structures, and subroutines, and learned more DOS function calls. It is also more skillful to use.