Entering Palettes

On the Sega Genesis, the palette consists of 64 colors. Think of it as a grid of 16 across and 4 down. Number the rows from 0-3, and the columns from 0-15. Then, every entry in column 0 is transparent.

Each color contains a 3-bit value for red, green, and blue (ranging from 0-7). 0 means no intensity, and 7 means full intensity. The color is stored as a 16-bit value. Bits 11-9 are blue, bits 7-5 are green, and bits 3-1 are red. Here are some examples of colors that you can make:
 *  $0000 = Black 
 *  $000E = Red 
 *  $00E0 = Green 
 *  $0E00 = Blue 
 *  $00EE = Yellow 
 *  $0EE0 = Cyan 
 *  $0E0E = Magenta 
 *  $008E = Orange 
 *  $0808 = Purple 
 *  $0888 = Gray 
 *  $0EEE = White 

How a palette might be stored in a 68K assembler
Palettes can be stored using the INCBIN directive. The contents of the file are then stored directly into the ROM. INCBIN	"C:\YourGame\Palette\Palette.bin" Palettes could also be stored directly using dc.w directives, then listing each color as a hexadecimal value.

How a palette might be stored in a dedicated Sega Genesis assembler
Rather than the palette being represented by its raw data, it could be shown as a grid with 16 squares across and 4 squares down. The columns are numbered $0-$F, and the rows are numbered $0-$3. Each square is colored according to the data.

The data appearance can be toggled to show either the grid, or the raw hexadecimal values. These values are shown as 16-bit values (using the "dc.w" directive), and are shown as 3 or 4 nybbles.