What Does # Mean in Assembly?

Question

For example, what would be the difference between, MOVE 8,D2 and MOVE #8,D2? Just wondering what the # represents and what would happen without it.

Answer 1

In GNU AS, if you use the # before anything else on a given line, the line will be ignored (comment). If use # before a value after an instruction, the value will be considered an immediate. If you want to use in-line comments at that point on the same line, you have to use C-style (i.e., /* comment here */) comments. For example:

# Write the palette to CRAM
lea Palette, a0                 /* Move palette address to a0 */
move.w #size_palette_w-1, d0    /* Loop counter = 8 words in palette */

Answer 2

in 68k assembly, the # sign denotes immediate constants. Everything else is normally considered an address:

move.w #6,d0

will load the constant immediate value 6 into register d0, while

move.w 6,d0

will do something entirely different: It will fetch the word at the constant address 6 into register d0