9-key keypads segment lcd module brands

Elegoo reached out to me by giving me their Ultimate Arduino Mega Starter Kit, which has many sensors, displays, and interactive elements. This project showcases how to connect and use the 4x4 Matrix Keypad with the 4-digit 7-segment display.

The first thing I did was go into Sketch->Manage Libraries and install the "SevSeg" library, which greatly helps with displaying numbers on the display. Then I connected the seven segment display by following this diagram:

MTS-88.C and I/O BOARD -08 has 8 (Eight) 7-segment displays and 20 key-pads on board. The displays are numbered from 7-SEG.1 to 7-SEG.8 and are connected to Port B’s PB7 to PB0 lines respectively. To display a character on a 7-segment display a byte has to be written to port B. The MSB 4 bits are the address of the 7-segment display and LSB 4 bits are the data. So if we write 58 H to port B then the 6th 7-segment display will show data 8.

The experiment is to read the keypad and display the pressed key id on the specified 7-segment display. In this experiment, I haven"t understood some lines in the assembly code I have shown below. I have made comments beside those lines which I haven"t understood.