Files with csw file extension might be found as part of some ZX Spectrum emulators from RamSoft.
There is one other file type using
the CSW file extension!
.csw - Corel WordPerfect setup information data
CSW file extension - Compressed square wave
What is csw file? How to open csw files?
File type specification:
The csw file extension is also used for a compressed square wave format used by some older ZX Spectrum emulators, developed by RamSoft.
Most likely some old format without support. No further information could be found.
This csw file type entry was marked as obsolete and no longer supported file format.
This type of file is no longer actively used and is most likely obsolete. This is typically the case for system files in old operating systems, file types from long discontinued software, or previous versions of certain file types (like documents, projects etc.) that were replaced in higher versions of their original programs.