ChiWriter

Description
.CHI files are a proprietary file format for the software ChiWriter.

ChiWriter was a popular word-processor for scientific purposes, circa 1990. Its popularity was based on the ability to type mathematical formulae in a WYSIWYG editor running in the MS-DOS operating system.

ChiWriter was created by Horstmann Software (Cay Horstmann) in 1986, and officially discontinued in 1996.