Hi, I haven't been on here in a long time, and I have a question. A year ago, I made a hacked Super Mario Bros .nes file. I then converted, or split, the .nes file into a .prg and a .chr file. I now only have the .prg and .chr file. How can I make them back into a .nes file, as in what's the easiest way? Thanks in advance.

Um, I think that command is wrong. I belive it's:

On un*x (including Mac OS X), you can do:

Ok, I did some looking and it seems that both be and KingMike where half right. The + is require to combine the files. However, the /b is required to do a binary copy. Otherwise, it assumes they're ASCII text, which probably trashed your ROM.

I suggest you make the header as a seperate file, then run:

You may not be copying the right number of bytes out of the original file for the header. The header itself is *16 bytes* which looks like 32 hex digits but is only 16 decimal digits (hex pane vs ascii pane.) Try just copying 16 instead of 32.

Gideon Zhi: I tried what you suggested.  It didn't work, but instead of the usual problem with the gray screen, when I try to open it in my emulator (VirtuaNES), I first get the message "Because a NES header is illegal, there can be the thing that does not work normally.  Do Execute?" (I always get that message when playing hacked games).  But then, after I click Yes, I get this message:   "Error:  Executed an Undefined order".  Just to be clear, when I open the regular unhacked SMB.nes file in my hex editor, I see this:  4E45531A020101000000000000000000, so before when I was copying 32 digits, I was copying the whole string you see there.  When I copied the 16 digits as you suggested, I just copied 4E45531A02010100.

UglyJoe: 
SMBHack.prg:  size:  33,066 bytes          size on disc:  36,864 bytes
SMBHack.chr:  size:  8,219 bytes            size on disc:  12,288 bytes

Again, thanks to everyone who is helping me with this.  I can't express my gratitude enough for how helpful everyone here has been.  This hacked game actually has some sentimental value to me, that is why it is so important to me that i restore it.

I think I'll just wait until you get back on and explain since I wouldn't really even know where to begin

Yep. This can be a major, major problem.

Of course, it is fixable (a short program could fix it, I believe), just time consuming.

Okay, here's how you can (hopefully) fix them.  Download Translhextion from here:

http://www.romhacking.net/utils/219/

Make a backup of your prg and chr files and then open one of them up in Translhextion.  Go to Search -> Replace.  Check the "Match case" option.  In the "Find what:" field, type "<bh:0d><bh:0a>" (without the quotes).  In the "Replace with:" field, type "<bh:0a>" (again, without the quotes).  Hit the "...following occurances" button.  You should see a popup that says "XX occurances replaced", where XX is a number that isn't 0.  Save the file and then repeat the process for the other file.

With any luck, the two files should now have the file sizes I listed above.  If they do, they're fixed and you should be able to combine them and make a nes rom by following the instructions earlier in the thread.  Good luck!