Re:Burroughs B 5500 Infomration Processing System (1964) [pdf]
by Cullinet on Friday February 04, 2022 @09:27AM
(#30207099)
"Burroughs software was designed to run only on proprietary hardware. For this reason, Burroughs was free to distribute the source code of all software it sold, including the MCP, which was designed with this openness in mind. "
so it should be around :
https://en.m.wikipedia.org/wiki/Burroughs_MCP