PL-6 manual : CP-6 Introduction to PL-6 - A beginner's guide to the PL-6 programming language (1988). The GNU 64-bit PL8 compiler - IBM research report describing the extension of PL8 to support 64-bit addressing, its implementation as a GCC front end, and the validation of the new compiler. Evaluation of PL8 as a language for highly reliable low-level programming. Wikipedia: XPL - Encyclopedia article containing brief history of XPL, references, and bibliography. Wikipedia: SabreTalk - Encyclopedia article with brief description, history, and example of SabreTalk. Dave Bodenstab's Home Page - The XPL compiler and supporting programs, ported to FreeBSD on an Intel 486. Guide to PL/S II - IBM manual describing the syntax of the PL/S Language. Space Shuttle Computers - HAL/S compiler system specification, manuals, language specification, programmer's guide, and HAL/S-FC users' manual. Wikipedia: HAL/S - Description of the design goals, syntax, and data types of HAL//S. Wikipedia: PL/S - Brief history of PL/S with links to documentation. An Overview of the PL.8 Compiler - Description of the internal operation of the IBM PL.8 compiler by Marc Auslander and Martin Hopkins. PLUM: The University of Maryland PL/1 System - Description of the structure of the PLUM compiler and runtime memory layout. XPL Programming Language - One of the original "compiler compilers", XPL is a derivative of PL/I and was widely ported. Documentation, links, and resources.