ALGOL 68S was designed as a subset of ALGOL 68

ALGOL 68

ALGOL 68 isan imperative computerprogramming language that was conceived as a successor to theALGOL 60 programming language, designed with the goal of a...

 in order to permit single-pass compilation. It was mostly for numerical computation.

Implementations

A compiler for ALGOL 68S was available for the PDP-11

PDP-11

The PDP-11 was a series of 16-bit minicomputers sold by Digital Equipment Corporation from 1970 into the 1990s, one of a succession of products in the PDP series. The PDP-11 replaced the PDP-8 in many real-time applications, although both product lines lived in parallel for more than 10 years...

, written in BLISS. The multiprocessor version designed for the C.mmp

C.mmp

The C.mmp was an early MIMD multiprocessor system developed at Carnegie Mellon University by William Wulf . The notation C.mmp came from the PMS notation of Bell and Newell, where a CPU was designated as C and a variant was noted by the dot notation; mmp stood for Multi-Mini-ProcessorSixteen...

 has been preserved at the PUPS archive of the PDP11 Unix Heritage society, c.f. http://www.tuhs.org/Archive/PDP-11/Applications/algol68.tar.gz.

Charles H. Lindsey has another ALGOL 68 implementation called ALGOL 68S for Sun3, Sun Sparc

SPARC

SPARC is a RISC instruction set architecture developed by Sun Microsystems and introduced in mid-1987....

 (under SunOS

SunOS

SunOS is a version of the Unix operating system developed by Sun Microsystems for their workstation and server computer systems. The SunOS name is usually only used to refer to versions 1.0 to 4.1.4 of SunOS...

 4.1), Sun Sparc (under Solaris 2), Atari ST

Atari ST

The Atari ST is a home/personal computer that was released by Atari Corporation in 1985 and commercially available from that summer into the early 1990s. The "ST" officially stands for "Sixteen/Thirty-two", which referred to the Motorola 68000's 16-bit external bus and 32-bit internals...

 (under GEMDOS

Atari ST

The Atari ST is a home/personal computer that was released by Atari Corporation in 1985 and commercially available from that summer into the early 1990s. The "ST" officially stands for "Sixteen/Thirty-two", which referred to the Motorola 68000's 16-bit external bus and 32-bit internals...

) and Acorn Archimedes

Acorn Archimedes

The Acorn Archimedes was Acorn Computers Ltd's first general purpose home computer to be based on their own ARM architecture.Using a RISC design with a 32-bit CPU, at its launch in June 1987, the Archimedes was stated as running at 4 MIPS, with a claim of 18 MIPS during tests.The name is commonly...

 (under RISC OS

RISC OS

RISC OS is a computer operating system originally developed by Acorn Computers Ltd in Cambridge, England for their range of desktop computers, based on their own ARM architecture. First released in 1987, under the name Arthur, the subsequent iteration was renamed as in 1988...

), c.f. http://www.cs.man.ac.uk/~chl#ALGOL%2068

Chief differences from ALGOL 68

• no union
• no flex but strings are handled specially
• no arrays inside structures (but references to arrays would be allowed) and a similar restriction on arrays of arrays (multidimensional arrays are nonetheless permitted)
• limitations on use of long and short to facilitate implementation on small computers
• no heap
• no parallel processing
• restrictions on the order of declaration and other small syntactic differences to make single pass compilation possible
• no formats

(summarised from Appendix 4 of the Informal Introduction)