FreeThreadMem

; Clears all memory accociated with a thread
; inputs    a  = Thread ID
FreeThreadMem:
    push af
    push bc
    push de
    push hl
    ld hl,UserRAM
    ld d,a
FTMLoop     ld a,(hl)
        push hl
        pop ix
        cp d
            call z,FreeMem
_       inc hl
        ld c,(hl)
        inc hl
        ld b,(hl)
_           inc hl
            djnz -_
        inc hl
        inc hl
        ; compare hl with UserRAMEnd
        ; if hl is smaller then jump back to FTMLoop
        ; otherwise continue
    pop hl
    pop de
    pop bc
    pop af
    ret