FlySpeed st/exp
From Just Solve the File Format Problem
st/exp is a file compression utility for DOS, and associated .PRS file format. st is the compressor, and exp is the decompressor. It's designed for good compression of text files.
It was developed by MicroComputer Square. It is part of a software collection named FlySpeed. FlySpeed seems to be something like a brand name.
The original filename is not stored in the compressed file. Decompressed files are given the filename extension .exp.
Identification
Unknown. PRS files have no obvious signature.
