<Li> Core rope, a form of transformer matrix ROM technology used where size and weight were critical . This was used in NASA / MIT's Apollo Spacecraft Computers, DEC's PDP - 8 computers, and other places . This type of ROM was programmed by hand by weaving "word line wires" inside or outside of ferrite transformer cores . </Li> <Li> Diamond Ring stores, in which wires are threaded through a sequence of large ferrite rings that function only as sensing devices . These were used in TXE telephone exchanges . </Li> <Li> The perforated metal character mask ("stencil") in Charactron cathode ray tubes, which was used as ROM to shape a wide electron beam to form a selected character shape on the screen either for display or a scanned electron beam to form a selected character shape as an overlay on a video signal . </Li> <P> Although the relative speed of RAM vs. ROM has varied over time, as of 2007 large RAM chips can be read faster than most ROMs . For this reason (and to allow uniform access), ROM content is sometimes copied to RAM or shadowed before its first use, and subsequently read from RAM . </P>

Which of the following is a kind of rom chip that contains