@Rik when you're reading:

It's not important, do you have the original photo of https://www.handheldmuseum.com/Guts/Bandai-UBoatGuts.jpg
Or the handheld itself, and can see the label?

Another trivia: I'm pretty sure that this is the JP version of Flight Time: https://www.handheldmuseum.com/Bandai/BattleBeam.htm

And one thing that is more interesting: https://www.handheldmuseum.com/Bandai/Galaxian.htm
There are 2 versions. One that has the Star Wars jingle at start, and one that has a jingle that sounds like Namco's Galaxian arcade. The 1st version(Star Wars I think) is on a NEC D553 MCU. So if your MCU note is correct, they ported the game over to NEC D7502G to just change the startup jingle.

Last edited by hap; 01/26/23 10:35 AM.