List:
byte 5             ;size byte
byte 1,2,3,4,5     ;the actual list
byte 0,0,0,0,0     ;free space

;NOTE: separating the above list into different rows is just for visual clarity - it makes no difference to the CPU!

AppendList:
;input: A = the value you wish to append.     ​
     ​ld hl,List
     ld a,(HL)                  ;get the size byte
     ld b,a                     ;store in B to use as loop counter for DJNZ
     inc hl			;increment HL past the "size byte" to the actual data.
         ​push hl                ;save this pointer for later
	 push af                ;save the value we want to append for later.

GotoEndOfList:
           ​inc hl
           ​djnz GotoEndOfList
;now, HL points to the first "free" byte.
	   pop af
	   ld (HL),a		;store at the end of the list
	pop hl			;go back to beginning of the list.
	inc (hl)		;add 1 to the size byte.
	ret