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