; Returns the amount of Free RAM
; output    hl = Free RAM
ReturnFreeRAM:
    push af
    push bc
    push de
    push ix
    ld hl,UserRAM
    ld bc,0
    ld a,$FF
_       cp (hl)
            jr nz,_
        inc hl
        ld e,(hl)
        inc hl
        ld d,(hl)
        push hl
            ld h,b
            ld l,c
            add hl,de
            ld b,h
            ld c,l
        pop hl
        jr ++_
_       inc hl
        ld e,(hl)
        inc hl
        ld d,(hl)
_       add hl,de       ; jump to next section
        ld de,UserRAMEnd    ; get the end of UserRAM
        sbc hl,de       ; compare
        add hl,de
        jr c,---_       ; loop again if hl < UserRAMEnd
    pop ix
    pop de
    pop bc
    pop af
    ld h,b
    ld l,c
    ret