Royal 12HT (UA221)
The Royal 12HT is a scientific calculator with algebraic logic. It has a VFD (vacuum fluorescent) display. The power source is 4xAA.
Facts at a glance:
If you have a Royal 12HT that is no longer working, you can first try replacing the 4xAA batteries. If that doesn't solve the problem, then you can consider replacing the calculator with a modern equivalent. We suggest the following current model as a replacement: