An 86k file extension is related to the TI-86 programmable calculator.
86K file extension - TI-86 constant data
What is 86k file? How to open 86k files?
File type specification:
The 86k file extension is associated with the TI-86 programmable calculator developed by Texas Instruments.
The TI-86 Graphing Calculator has been discontinued and is no longer available.
The 86k file contains mathematics constants.
This 86k 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.