Also, I must say, unless you get an updated ROM in your 1541, it's imperative that you always specify the drive number in your commands.
To format a disk, don't use N: but rather use N0: specifying drive zero.
A 1541 only has drive zero, it has no drive one. But there's a bug in the ROM, which was originally written for dual-drive units, that will corrupt your disks. It's called the SAVE @ REPLACE BUG. As far as anyone knows it only occurs when you use @ to save with replace. So if you never do that, it shouldn't matter. But, it's best to be safe, and make a habit of it.