From the archive: PPMd program is file-to-file compressor, it is written for embedding in user programs mainly and it is not intended for immediate use. I was interested in speed and performance improvements of abstract PPM model [1-5] only, without tuning it to particular data types, therefore compressor works good enough for texts, but it is not so good for nonhomogeneous files (executables) and for noisy analog data (sounds, pictures etc.).

ftp://ftp.elf.stuba.sk/pub/pc/pack/ppmdi1.rar