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Assembly A86 - Time to receive and display

I am working on the Assembly program to get the system time and date, convert it to ASCII and display it on the monitor. I am having problems so that it displays correctly and cannot find where I made a mistake. This is for the assignment, and I prefer to have explanations, not just solutions, if possible. Here is my code:

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

And this is what I get when I run it at 9:11 AM 02/19/2012:

The current time is: 09:00:00
The date is: 02/09/0005

, , , , - . , , TIME, , , , , . .

: , ... . :

9:23 19.02.2012

The current time is: 09:23:02
The date is: 02/09/0005

EDIT2: ! [DATE] - . , , 4 - 16 , 8! - SHR 4 ! :

The current time is: 09:43:02
The date is: 02/19/0015

EDIT 3: CVT_CT, ASCII [DATE], ...

The current time is: 10:06:02
The date is: 02/19/0015

EDIT 4: ... . !!! !

The current time is: 10:09:02
The date is: 02/19/2015

: , 02?

+4
1

( ) BCD , - , , , .

, , DRY ( ) ( WET ( ). Wikipedia DRY - .

, (.. ), , , , , . >

, BCD . ( , , , ).

, , put_bcd2 , - , . , , , .

; Main program.

    call    get_date            ; get date/time into string.
    call    get_time

    lea     dx, output          ; then output the string.
    mov     ah, 09h
    int     21h

    mov     ax, 4c00h           ; exit program.
    int     21h

; Variables.

output:
    db      "The current date is: "
date:
    db      "00/00/0000", 0dh, 0ah
    db      "The current time is: "
time:
    db      "00:00:00", 0dh, 0ah, '$'

; Subroutines.

; Gets the date and inlines it into the output.
get_date:
    mov     ah, 04h             ; get date from bios.
    int     1ah

    mov     bx, offset date     ; do day.
    mov     al, dl
    call    put_bcd2

    inc     bx                  ; do month.
    mov     al, dh
    call    put_bcd2

    inc     bx                  ; do year.
    mov     al, ch
    call    put_bcd2
    mov     al, cl
    call    put_bcd2

    ret

; Gets the time and inlines it into the output.
get_time:
    mov     ah, 02h             ; get time from bios.
    int     1ah

    mov     bx, offset time     ; do hour.
    mov     al, ch
    call    put_bcd2

    inc     bx                  ; do minute.
    mov     al, cl
    call    put_bcd2

    inc     bx                  ; do second.
    mov     al, dh
    call    put_bcd2

    ret

; Places two-digit BCD value (in al) as two characters to [bx].
;   bx is advanced by two, ax is destroyed.
put_bcd2:
    push    ax                  ; temporary save for low nybble.
    shr     ax, 4               ; get high nybble as digit.
    and     ax, 0fh
    add     ax, '0'
    mov     [bx], al            ; store that to string.
    inc     bx
    pop     ax                  ; recover low nybble.

    and     ax, 0fh             ; make it digit and store.
    add     ax, '0'
    mov     [bx], al

    inc     bx                  ; leave bx pointing at next char.

    ret
+2

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