Since its earlier versions starting in the 80’s, Portable Standard LISP has undergone several changes.
PSL was developed for mainframe systems e.g. of /370 and Vax type running proprietary operating systems of the manufacturers. Today most PSL versions run on workstations with RISC processors running a Unix type operating system.
Today PSL is mostly used a deliverly vehicle for LISP based systems, e.g. the computer algebra system REDUCE and not as a LISP dialect of its own right.
The support and maintainance for PSL is mostly done at ZIB in Berlin.
Recently, the internal representation of identifiers was changed in order to support a 256 character set and case sensitivity. This causes a binary incomptibility of .b files with older versions such as PSL 3.4.
This document describes the changes and newer developments for PSL done at ZIB in order to improve performance and to work with new application types such as parallel processing.
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