ProPack, by Rob Northen, is a programmer’s compression utility. Its packed data is commonly identified with RNC, the initials of Rob Northen Computing. The package supplies both packing programs and assembly routines for restoring the data.
Northen is also associated with Copylock, but compression has a different purpose: representing a program or its data in fewer bytes while providing a way to recover what it needs.
Smaller output or quicker unpacking
The February 1992 manual distinguishes two methods. Method 1 aims for smaller packed files; method 2 aims for faster unpacking. The programmer chooses according to the application. Neither description guarantees a particular saving or speed for every file.
It also separates packed data from packed executables. Data requires a decoder supplied by the consuming program. An executable includes startup code to unpack itself and, where necessary, adjust addresses. The documented formats include Amiga, Atari ST and PC programs, alongside raw data and machine-code forms.
A routine inside another program
The distributed SOURCE directory contains assembly unpackers for several processors. These make the receiving side visible: a game can include a decoder and call it when packed material is needed, rather than treat every asset as an independent self-extracting program.
That reuse continued beyond original games. WHDLoad’s own credits name Northen for its RNC1/2 decompression routines. The format could remain part of loading and compatibility work after the software it carried had moved to different storage.
Verify the right thing
ProPack provides a verify operation, but its manual also distinguishes correct execution from an identical file. Packing can optimise a PC relocation table or discard Amiga debugging hunks. The restored executable can therefore differ from its original disk representation.
That matters when preserving an original release. Turbo Imploder documents a similar boundary: recovering the code needed to run is a different claim from reproducing every byte that was distributed.
Sources
- Rob Northen Computing, PRO-PACK Instruction Manual: Original instruction manual, February 1992, preserved with the distributed package; sections 1, 3, 4 and 5.
- Rob Northen Computing, distributed unpacking routines: Original distributed assembly unpackers for several processor families, separate from the packing executables.
- WHDLoad, Copyright, License, Disclaimer: Independent software project’s credits acknowledge Northen’s RNC1/2 decompression routines.