NuFX
NuFX (NuFile Exchange; also known as ShrinkIt format) is an archiving format that was used for the Apple II series late in its history. It was created by Andy Nicholas as a student project at Moravian College in Bethlehem, Pennsylvania. The ShrinkIt program (also created by Nicholas) supports it. It usually uses LZW compression.
The usual filename extension is .shk. When NuFX-format data is placed into Binary II format for transfer, extension .bxy is used.
NuFX also supports storing disk images. Files using this feature typically have extension .sdk.
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Format details
Two slightly different CRC algorithms are used, by different parts of the format: CRC-16/XMODEM and CRC-16/IBM-3740.
Identification
NuFX files start with bytes 4e f5 46 e9 6c e5. This is ASCII "NuFile", but with the high bit set on alternate bytes.
Specifications
- Apple II File Type Notes - ShrinkIt / NuFX
 - ARCHIVE FORMATS AND DATA, by Raymond Clay, "NuFX - SHRINKIT" section
 
Software
- NuLib, NuLib2, NufxLib
 - NuLib v3.24 (DOS software)
 - Shink-Fit X - Mac OS X archiver compatible with ShrinkIt
 - ShrinkIt
 - Deark (limited features)
 
Sample files
Links
- NuFX format described (A2-Central, Aug. 1989)
 - Hacking data compression (gives lots of format details)
 - What are ShrinkIt files?