6c4

clock   MACRO
        LOCAL tmval_str,calc,out_time,over_data,oldcol,oldrow

        push ax                            ;Save registers on stack
        push bx
        push cx
        push dx        
        push bp
        push si

	mov ah,02H                         ;Read real time clock time
	int 1aH

	mov bp,OFFSET tmval_str
	mov si,0

	mov bl,ch
	call calc
	mov bl,cl
	call calc

        jmp out_time                       ;Write time to screen
	
calc:
	mov al,bl
	shr al,1                           ;We want the high nibble...
        shr al,1
        shr al,1
        shr al,1
        
        and al,0fh
	add al,30h
	mov byte ptr [bp+si],al            ;first character
	inc si

	mov al,bl
	and al,0fh
	add al,030h
	mov byte ptr [bp+si],al            ;second character
	inc si
	inc si                             ;skip over the ':'

	ret

	
out_time:
        mov ah,0fh
        int 10h

        mov ah,03h
        int 10h
        mov oldcol,dl                      ;Save old cursor position
        mov oldrow,dh

        mov dl,75                          ;Place cursor in upper right corner
        mov dh,0
        mov ah,02h
        int 10h
        
	mov ah,09H                         ;Write time to screen
	mov dx,OFFSET tmval_str
	int 21H

        mov dl,oldcol                      ;Restore old cursor position
        mov dh,oldrow
        mov ah,02
        int 10h

        pop si                             ;Restore registers
        pop bp
        pop dx
        pop cx        
        pop bx
        pop ax

        jmp Over_data

oldcol db 0
oldrow db 0
tmval_str  db 2 dup (0),':',2 dup (0),'$'
Over_data:
        ENDM
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