Editing Pascal (programming language) (section)

==={{anchor|Pascal-P}}The Pascal-P system===
To propagate the language rapidly, a compiler ''porting kit'' was created in Zürich that included a compiler that generated so called [[p-code machine|p-code]] for a ''virtual'' stack machine, i.e., code that lends itself to reasonably efficient interpretation, along with an interpreter for that code – the ''Pascal-P'' system. The P-system compilers were named Pascal-P1, Pascal-P2, Pascal-P3, and Pascal-P4. Pascal-P1 was the first version, and Pascal-P4 was the last to come from Zürich. The version termed Pascal-P1 was coined after the fact for the many different sources for Pascal-P that existed. The compiler was redesigned to enhance [[software portability|portability]], and issued as Pascal-P2. This code was later enhanced to become Pascal-P3, with an intermediate code [[backward compatible]] with Pascal-P2, and Pascal-P4, which was not backward compatible.

The Pascal-P4 compiler–interpreter can still be run and compiled on systems compatible with original Pascal (as can Pascal-P2). However, it only accepts a subset of the Pascal language.

Pascal-P5, created outside the Zürich group, accepts the full Pascal language and includes ISO 7185 compatibility.

Pascal-P6 is a follow on to Pascal-P5 that along with other features, aims to be a compiler for specific CPUs, including AMD64.

[[UCSD Pascal]] branched off Pascal-P2, where [[Kenneth Bowles]] used it to create the [[Interpreter (computing)|interpretive]] UCSD p-System. It was one of three operating systems available at the launch of the original [[IBM Personal Computer]].<ref>[http://www.cbi.umn.edu/oh/pdf/oh392jb.pdf cbi.umn.edu], "An Interview with John Brackett and Doug Ross"{{dead link |date=March 2018 |bot=InternetArchiveBot |fix-attempted=yes}}, p15, Charles Babbage Institute, 2004</ref> UCSD Pascal used an intermediate code based on byte values, and thus was one of the earliest ''[[bytecode]] compilers''. [[Apple Pascal]] was released in 1979 for the Apple II and [[Apple III]] computer systems. It was an implementation of, or largely based on, UCSD Pascal. Pascal-P1 through Pascal-P4 were not, but rather based on the [[CDC 6600]] 60-bit word length.

A compiler based on the Pascal-P4 compiler, which created native binary [[OS/360 Object File Format|object files]], was released for the [[IBM System/370]] [[mainframe computer]] by the [[Australian Atomic Energy Commission]]; it was named the ''AAEC Pascal 8000 Compiler'' after the abbreviation of the name of the commission.<ref>{{cite report |url=http://www.iaea.org/inis/collection/NCLCollectionStore/_Public/10/477/10477561.pdf |date=1977 |title=Australian Atomic Energy Commission Research Establishment, Lucas Heights, Nuclear Science and Technology Branch Report, Divisional Research |page=22 |website=International Atomic Energy Agency (IEAE)}}</ref>