I bought the display in 90's and it was in a box without a paper, therefore I started to look for his properties. It is a 16 x 2 display. In internet there are more referencies, I found, that it is compatible with HD44780. This means pin compatibility and because it can also execute commands, there is surely an instruction code compatibility. However, there are more possibilities, variants of the pin sequence from left to right, but the pins order should not be disturbed. Firstly I found the GND pin(s) measuring the resistance against the metal frame of the display.
7.9 V from power supply unit, which should be between 7 and 12V is downgraded on the Arduino board to 5V.
I have used an ohm-meter to find were (left or right) are the 8 data /command
pins. I have measured the resistance against GND and the 8 pins should have
same resistance, of course. Other pins have another resistance against GND.
Here is the result of my investigation:
K and A pins are for backlight kathode, anode, I don't use them. There is a possibility to use the DB0-DB7 in 8-bit mode or in 4-bit mode using DB4-DB7. I have used the second variant. We have to adjust contrast on V0 pin using a trimmer as a voltage divider. Its value is not critical, it can be in range from 5k to 25k. Without properly adjusted voltage on V0 pin could happen, that we see nothing.
For testing the LCD display I have written hello world program in C and in BASCOM:
The pin names correspond to the pin names on Arduino board - see picture above.