There are 2 repositories under bcpl topic.
Historical sources for the TRIvial Operating System
Essex BCPL for TOPS-10
The BCPL compiler, based on the original BCPL compiler which had been written by Martin Richards. Copyright (c) 2012 Robert Nordier. All rights reserved.
OS for the Intel 80486 written in BCPL
BBN's TENEX BCPL
A music composition program for the Amstrad CPC computer