TD0 File access?

[rprosperi]

.TD0 files are in Teledisk format, a DOS-vintage utility for making a floppy disk binary (not simple ASCII) image file intended to be sent electronically, at the time meaning modem transfer via phone lines, hence the name Teledisk.

See this site for info on the format and to get a copy of the utility, which BTW runs only on real DOS (in fact old/slow PC hw) with real vintage floppy drives (typically 5.25" 360K):

http://www.classiccmp.org/dunfield/img54...ledisk.htm

There is also useful info here, presuming that file is for use with some HP equipment:

https://groups.io/g/hpseries80/topic/655...100,655937

More details on what you're trying to do (machine type, programs, etc.) will help get you better answers.