ATMEGA 2560 programing

[amitash]

Hi,
I try to upload a sketch to a ATMEGA 2560 using the arduino IDE and get the following (after upload done....):

avrdude: verification error, first mismatch at byte 0x0634
         0x0e != 0x06
avrdude: verification error; content mismatch

What can it be?
Thanks

[cmiyc]

How old is the board?

Do you have !!! anywhere in your code (other than comments)?

[amitash]

The board is new (it is not an arduino board but I use the arduino IDE).
Yes I have some Exclamation marks in the code. Why?

[amitash]

Another thing, some of the exclamation marks are for logic not calculation.

[nickgammon]

Some bootloaders use !!! as an "escape" to go into command mode.

[amitash]

Does it have to be 3 in a raw?

[nickgammon]

Yes.