Hex display (decoded)
Trainer hex readout · VCC 5 V · four TTL-level inputs D0–D3 (D0 = 1s bit) · shows 0–F · inputs read high above 2 V

Try it on the benchThe lab drops it on an empty bench and opens its datasheet card.
Pins
- VCC
- GND
- D0 (1)
- D1 (2)
- D2 (4)
- D3 (8)