A Heathkit ET-3400 Simulator.
The app simulates a Heathkit ET-3400. This was an inexpensive computer from 1977 for people to learn about computing and programming.
With the app you can enter programs in machine code using the keypad and see the result on the 6 LED digits. It emulates the Motorola 6800 8 bit processor and contains the original ROM and 256 bytes of RAM