Galaga was a popular arcade game developed and released by Namco (Midway in N. America) in 1981. It had amazing, fast, smooth 2D-sprite graphics, and relied on Namco hardware that utilized 3 Z80 CPUs running at ~3 MHz.
I am aware from the limited information found online that the 3 Z80s were divided up as one main CPU, and a co-processor each for sound and graphics. I'm mostly interested in how the Z80 for graphics processing was utilized to manage the drawing of all the sprites. Although, I would assume a similar means of sharing data existed for the sound co-processor too.
I think it is noteworthy that none of the 8-bit single CPU home or console systems of the 1980s faithfully reproduced this game. There was a weak port for the Atari 7800 and a decent, serviceable port for the NES, which still falls well short of the arcade game graphics. So I am guessing that the sprite hardware available for the top 8-bit home systems was no match for Namco's custom graphics hardware.
How did the Namco hardware create such an effective graphics rendering engine from slow, cheap, multiprocessing Z80 CPUs?