WOW!!!! Thank you soooooo much, Laschek! It is "N-Sub". I forgot about the enemy submarines also shooting at you and I forgot that your submarine goes up and down in addition to left and right.
You tube link:
www.youtube.com/watch?v=klHJs7ZPnns
For Modessitt, Blinddog, Leinhit, and Gorfchampion, thank you for suggesting Fire One!, Up Scope, Run Deep, and Tora Tora.
This web site, International Arcade, does not have a picture of N-Sub, so I wasn't completely sure. I did a regular google search for N-Sub and found the youtube video, and that was it, no question. I've been racking my brains because I used to play that game all the time. There was an arcade near where I had a summer job in 1980 and I played N-Sub on my lunch breaks. I got to be excellent at it. I've looked for that game off and on for the past ten years. I was pretty happy when I found this site. I went through the lists on this web site and looked at every nautical sounding game, but I didn't see it. Hence my desperate plea. I never would have guessed it was hiding in the N's.
Thank you Laschek. Now I just need to find one to buy. It is listed as very rare. Only one person has it. It is not listed on Ebay.
Thanks again everybody. I consider this thread to be closed. I'm going to start a new one with the title, "Wanted: N-Sub."
Bye.