Trivia
Atari 2600 programmer Mark Ackerman, at the time working in Atari's "think-tank" GCC, was granted a patent for his technique invented for the 2600 port of Galaxian, allowing eight sprites to be displayed in one row.
Atari's 2600 release of Galaxian came with the comic book Atari Force #5. Here is that comic at AtariAge.com
Was later re-released under the Thunder Mountain label. What makes this trivia? Usually only Mindscape games were released under Thunder Mountain... Galaxian was originally licensed to Atari.
Galaxian (and its clone, Cosmic Crusader) get away with relatively high framerates on the original 4.77MHz PC because they don't use the entire screen for a playfield; the right fifth of the screen (64 pixels) is unused. Another side-effect of shortening the playfield to a width of 256 pixels is the optimization of game calculations, stemming from the fact that horizontal coordinates fit in a single byte instead of two.