Atmega 1281

Hello i have one problem, i have to replace a firmware in a minitronics board where there is an at1281. With arduino software I found only the 1280 can someone help me to solve the problem? Thanks

Search your IDE folders for a /variants folder. Copy a 1280 board section of boards.txt into a new folder and update it to reflect 1281, new board name, new signature bytes. Restart IDE, new board should appear. Will need some more steps, that will get you started.