be in a substantially u201c off u201d state despite sub segment 42 a being in an u201c on u201d state similarly in fig1 b although sub segment 42 b is illustrated as having failed in an u201c off u201d state the bi stable segment 15 still appears to be in a substantially u201c on u201d state another sub segment embodiment is illustrated in fig1 a and 11b a first sub segment 44 a forms the word u201c error u201d while a second sub segment 44 b makes up the border of the segment when operating correctly both sub segments are in the correct state so that the word error does not appear to the user of the device i e the segment 15 appears all white or all dark however if one of the sub segments 44 a 44 b fail the word error will appear to the user for example in fig1 a sub segment 44 b is illustrated in the off state while sub segment 44 a is illustrated in the on state therefore the word error appears as dark text within the segment 15 conversely in fig1 b sub segment 44 b is in the on state while sub segment 44 a is in the off state this causes the word error to appear within the segment 15 as white text in both cases the user may be notified that the information that is displayed may contain errors and there may be a problem with the display the use of the word u201c error u201d is only one example as other words or symbols may be utilized embodiments of the present disclosure incorporate a bi stable display into a device such as a medical diagnostic device 10 embodiments may also.