Triangular uOS v1.25 Software Development Kit by Michael Goral (Released November, 2022) - This archive includes the Programmers Reference Guide, a memory map spreadsheet,  and the system variables spreadsheet.  Everything you would need to start developing for Triangular u)S is included. 

Here's a link to the Triangular uOS v1.25 released in August, 2022.

Here's a link to the Triangular uOS v1.25 User's Manual