NIB file extension

The nib file extension is related to a special disk image used in old Apple computers. A "disk image" is typically a file containing every data byte on a diskette,i.e. Catalog tracks, files, DOS (if present) etc.. One kind of disk image, NIB, tries to preserve all disk information (e.g. sector headers, sync bytes, etc.).

Apple II emulators running on a PC, Mac, etc. treat disk image files like diskettes. Disk image files are also a handy way to archive Apple II disks on hard disk and to maintain wares on ftp and other download sites.

Some copy protected diskettes can be converted to another kind of disk image called "NIB". Saltine's Super Transcopy (SST) incorporates bit copy routines to attempt to produce a nibblized disk image of a 5.25" diskette.

On your Apple II, SST reads the disk bytes from half a disk and stores that data on a whole normal disk. Then it does the same for the second half. These two disks can be converted to .dsk disk images and moved to a PC or Mac. There, the .dsk images are merged into a NIB image using SST running on an emulator.

If successful, you have a .nib file which can be used like a diskette on popular Apple II emulators. (For one or two older emulators, .nib files are the only useable images.).

The standard length of a .nib file is 232,960 bytes-- much larger than a DSK. However, since .nib files include sector address header and other non-data 'embedded' diskette information, they can be used to image many protected disks.

Naturally, a .nib file preserves DOS 3.3 volume numbering. This allows programs which use volume numbers to identify their disks to run on emulators. Many disks with no copy protection are in .nib form instead of .dsk because the game, etc. which uses the disks needs to check volume numbering.