View source for SG-1000

First, there are only 15 fixed and hardcoded colors, 0th item is for transparency.
Second, each tile consists of 8 lines, each line defines a foreground and background color. 
It is possible that a tile consists of 15 different colors.
Third point, 768 tiles in total. 
The screen is divided into 3 areas(top, center, bottom), each area have its own 256 tiles. 
For example if you want to fill your screen with a '$' tile, you need this tile 3 times for each area once.

https://www.smspower.org/Development/Palette