S3

S3, S-3 or S03 may refer to:

Film

Transportation

Airlines

Locomotives

S-Bahn lines

Cars

Motorcycles

Roads

Trisulfur

The S
3 molecule or trisulfur or sulfur trimer or thiozone or triatomic sulfur is an allotrope of sulfur. It occurs as a mixture in liquid and gaseous sulfur and also at cryogenic temperatures as a solid. Under standard conditions it is unstable and self reacts to solid sulfur cyclooctasulfur. The molecule shape is similar to ozone.S
3 is found in sulfur vapour, comprising 10% of vapour species at 713 K (440 °C; 824 °F) and 1,333 Pa (10.00 mmHg; 0.1933 psi). It is cherry red in colour, with a bent structure, similar to ozone, O
3. The bonds between the atoms are not full double bonds (as this would require two fewer electrons, similar to carbon disulfide), and the molecule can be thought of as a resonance between two states, in each of which one of the end atoms has a negative formal charge while the central atom has a positive formal charge.

The molecule has a distance between sulfur atoms of 191.7 ± .01 pm (1.9170 ± 0.0001 Å) and angle at the central atom of 7000204831841014054♠117.36°±0.006°. However, cyclic S
3, where the sulfur atoms are arranged in an equilateral triangle with three bonds (similar to cyclic ozone), should in theory be lower in energy than the bent structure actually observed.

S3 (programming language)

S3 is a structured, imperative high-level computer programming language. It was developed by the UK company International Computers Limited (ICL) for its 2900 Series mainframes. It is a system programming language with syntax influenced by ALGOL 68 but with data types and operators aligned to those offered by the 2900 Series. It was the implementation language of the operating system VME.

Annotated Example

A rare example of an S3 program available in the public domain is the implementation of Kermit developed at the South-West Universities Regional Computer Centre, and archived in the Columbia University archive of Kermit implementations. The examples below are selected highlights of the main module (kmt_main_module).

The program starts with a module identification, and comments which we quote by way of acknowledgment to the authors:

Next follow a number of "mode declarations". Mode is the Algol 68 term for a type.

The first type is an array of 96 bytes; the next two are references (pointers) to arrays of bytes. KMT_MTM_VALUES is a union type allowing a variety of different types to appear. Note that WORD is a 32-bit unsigned integer, INT is a 32-bit signed integer; LONG makes it 64 bits. The last option in the union is marked REF()REF()BYTE, which means it is a pointer to an array whose members are pointers to arrays of bytes.