XPL is a dialect of PL/1 documented in the book "A Compiler Generator" by McKeeman, Horning and Wortman, published by Prentice-Hall, 1970, ISBN 13-155077-2. In 1996 David E. Bodenstab ported the compiler to the Intel 486 running on FreeBSD Unix. In 2020 Daniel E. Weaver ported the compiler to Linux.
As of November 2020 the Linux port runs on both Linux and the Apple MAC. However Apple has deprecated the 32 bit mode of the Intel processors. This XPL compiler is not compatible with 64 bit...