HP HP-97 - Display

Theory of Operation HP-97
2-3. DISPLAY
2-4, The display consists of a 15-digit light emitting diode (LED) module
plus a low battery indicator which are controlled in part by each of the
following components:
a. ACT.
b. ROM 0.
c. Anode buffers.
d. Cathode driver.
2-5. Each digit consists of seven LED segments with an additional segment
for the decimal, which makes eight segments, sequentially lettered a
through h as shown below.
Figure 2-2. LED Digit
2-6. Since the display is a scanned diode array, both its anode and
cathode must be driven in order for the segment to light. All cathodes of
each digit are tied together, as shown in figure 2-3. When a cathode