I hold in my hand the Mattel Electronics Basketball game I played when I was growing up.
In addition to the lack of a 3-point shot line (not that you could have much of a shot-line with only a 5x5 pixel array), the game is also different from modern NBA games in that each of the four quarters lasts for 15 minutes, not 12 minutes.
Did NBA games used to have 15 minute quarters?
YOu have the 1978 version of the game. Each quarter(on your game) only lasted about 2.5 min. It may have said 15 minutes on the game clock, but the NBA played 12 min. quarters. Perhaps this could be termed “all your basketball belong to us.”
The NBA introduced the three point line in 1979, and Mattel redid the game in 1980. That version correctly said, in their instruction book, that quarters in the real NBA were 12 minutes.
If you go to that site, click on “view manual” at the top. You can view both manuals.