I do not know if it's exacly what you want but here is one part of a code for video that I found in a old asm project for school that I have made.
Code:
PTAMPON PROC
        PUSH    AX
        PUSH    CX
        PUSH    DI
	MOV 	SI, 0
        MOV     AX, 0B800h
        MOV     ES, AX
        MOV     AL, BYTE PTR TAMPON[SI]            ; string to show here!!!!        
MOV     AH, 0f3h            ; color here!!!!
        MOV     DI, 1940d          ; x_yposition here!!!!!

Encore:	INC SI
        MOV     WORD PTR[ES]: DI, AX ; copie dans l'‚cran vid‚o
        INC     DI                 ; next char
        INC     DI ;Next char
	
	MOV     AL, BYTE PTR TAMPON[SI] 
        CMP	AL, '$'     	   ; end?
        JNE     Encore             ; not = redo


FINTAMPON:

        POP     DI
        POP     CX
        POP     AX
	RET
ENDP