Something

DATA;
message:
 db 'Hello World!',0;
alloc col1,000999;
col2:
 db 000999;
alloc ON,0;
 
WriteString: //ESI - String pointer, EDX - Param
  mov eax,65536;
  AWriteLoop:
    cmp #esi,0; //Terminate on char 0
    je AEnd;
    mov #eax,#esi; //Output char
    inc eax;
	cmp ON,1;
	je RED;
	mov #eax,col1; //Output char param
    inc eax;
    inc esi;
	inc ON;
	jmp ENDLOO;
	RED:
    mov #eax,col2; //Output char param
    inc eax;
    inc esi;
	dec ON;
	ENDLOO:
  jmp AWriteLoop;
  AEnd:
  ret //Return from call

CODE;
  mov esi,message;
  mov edx,000999; //White foreground on black background
  call WriteString;