Write a program in assembly language to read the current time and Date from the system and display it in the standard format on the screen.

TITLE GETDTTM

PAGE 60, 132

;   This program retrieve the system date and time,

;   converts it to ASCII, and displays it to the screen

;   Define constants

;

CR      EQU 0DH ;define carriage return

LF      EQU 0AH ;define line feed

EOM     EQU '$' ;define end of message marker

NULL    EQU 00H ;define NULL byte

;

;   Define variables

;

JMP START

PROMPT  DB  CR, LF, "The current time is: ",EOM

PROMPT2 DB  CR, LF, "The date is: ",EOM

TIME    DB  "00:00:00", CR, LF, EOM

DATE    DB  "00/00/0000", CR, LF, EOM

;

;   Program code

;

START: 

CALL GET_TIME   ;call function to get system time

CALL GET_DATE   ;call function to get system date

LEA DX, PROMPT  ;print time prompt to screen

MOV AH, 09H

INT 21H

LEA DX, TIME    ;print time

MOV AH, 09H

INT 21H

LEA DX, PROMPT2 ;print date prompt to screen

MOV AH, 09H

INT 21H

LEA DX, DATE    ;print date

MOV AH, 09H

INT 21H

CVT_TIME:   ;converts the time to ASCII

CALL CVT_HR

CALL CVT_MIN

CALL CVT_SEC

RET

CVT_HR:

MOV BH, CH  ;copy contents of hours to BH

SHR CH,4    ;convert high char to low order bits

ADD CH, 30H ;add 30H to convert to ASCII

MOV [TIME], CH  ;save it

AND BH, 0FH ;isolate lower 4 bits

ADD BH, 30H ;convert to ASCII

MOV [TIME+1], BH    ;save it

RET

CVT_MIN:

MOV BH, CL  ;copy contents of minutes to BH

SHR CL, 4   ;convert high char to low order bits

ADD CL, 30H ;add 30H to convert to ASCII

MOV [TIME+3], CL    ;save it

AND BH, 0FH ;isolate lower 4 bits

ADD BH, 30H ; convert to ASCII

MOV[TIME+4], BH ;save it

CVT_SEC:

MOV BH, DH  ;copy contents of seconds to BH

SHR DH, 4   ;convert high char to low order bits

ADD DH, 30H ;add 30H to convert to ASCII

MOV [TIME+6], DH    ;save it

AND BH, 0FH ;isolate lower 4 bits

ADD BH, 30H ;convert to ASCII

MOV[TIME+7], BH ;save it

GET_DATE:   ;get date from the system

    MOV AH, 04H    ;BIOS function to read date

    INT 1AH        ;call to BIOS, run 04H

    CALL CVT_DATE

    RET

;CH = Century

;CL = Year

;DH = Month

;DL = Day

;CF = 0 if clock is running, otherwise 1

CVT_DATE:

    CALL CVT_MO

    CALL CVT_DAY

    CALL CVT_YR

    CALL CVT_CT

    RET

CVT_MO:     ;convert the month to ASCII

MOV BH, DH  ;copy month to BH

SHR BH, 4   ;convert high char to low order bits

ADD BH, 30H ;add 30H to convert to ASCII

MOV [DATE], BH  ;save in DATE string

MOV BH, DH  ;copy month to BH

AND BH, 0FH ;isolate lower 4 bits

ADD BH, 30H ;convert lower bits to ASCII

MOV [DATE+1], BH;save in DATE string

RET

CVT_DAY:    ;convert the day to ASCII

MOV BH, DL  ;copy days to BH

SHR BH, 4   ;convert high char to low order bits

ADD BH, 30H ;add 30H to convert to ASCII

MOV [DATE+3], BH    ;save in DATE string

MOV BH, DL  ;copy days to BH

AND BH, 0FH ;isolate lower 4 bits

ADD BH, 30H ;convert lower bits to ASCII

MOV [DATE+4], BH;save in DATE string

RET

CVT_YR:     ;convert the year to ASCII

MOV BH, CL      ;copy year to BH

SHR BH, 4       ;convert high char to low order bits

ADD BH, 30H     ;convert to ASCII

MOV [DATE+8], BH    ;save it

MOV BH, CL      ;copy year to BH

AND BH, 0FH     ;isolate low order bits

ADD BH, 30H     ;convert to ASCII

MOV [DATE+9], BH    ;save in DATE string

RET

CVT_CT:     ;convert the century to ASCII

MOV BH, CH      ;copy century to BH

SHR BH, 4       ;convert high char to low order bits

ADD BH, 30H     ;convert to ASCII

MOV [DATE+6], BH    ;save it

MOV BH, CH      ;copy century to BH

AND BH, 0FH     ;isolate low order bits

ADD BH, 30H     ;convert to ASCII

MOV [DATE+7], BH    ;save it

RET

;

;Program End

;

End