Southampton BASIC System (SOBS) was a dialect of the

BASIC BASIC (Beginners' All-purpose Symbolic Instruction Code) is a family of general-purpose, high-level programming languages designed for ease of use. The original version was created by John G. Kemeny and Thomas E. Kurtz at Dartmouth College ...

programming language developed for and used on ICT 1900 series computers in the late 1960s and early 1970s; it was implemented as an incremental BASIC interpreter under the MINIMOP operating system at the University of Southampton and also ran under MAXIMOP. It was operated from a Teletype terminal, though CRT terminals could also be used.

Language characteristics

In common with many early implementations of BASIC, SOBS needed lines to have line numbers, both to allow a user to add new lines to the program in the desired place and also as targets for GOTO and GOSUB statements. A RENUMBER facility was available to allow for sections of the code to be renumbered, by default in increments of 10, to allow more space in the middle of a program. Other than line numbers, all numeric values were represented internally as floating point.

Statements

The language had relatively few statements by comparison with modern programming languages: Note in particular the lack of a WHILE-like statement; FOR was the only looping construct available to programmers.

Variables

Variable Variable may refer to: * Variable (computer science), a symbolic name associated with a value and whose associated value may be changed * Variable (mathematics), a symbol that represents a quantity in a mathematical expression, as used in many ...

names for numeric values were either a single letter, or a single letter followed by a single numeric digit, thus allowing for 286 discreet variables in total. Strings were supported; variable names for them had the same restriction but were followed by a pound (£) symbol.

Functions

A limited number of numeric functions were provided, all of which took one numeric parameter: Support for strings was more limited, with only one function, LEN, which returned the length of the string parameter. Sub-strings were supported with square brackets, so

A£ ,3/code> referred to the sub-string of the string A£ from the 2nd character to the 3rd character inclusive, so

10 LET A£ = "FOO"
20 PRINT A£ ,3
would print OO

This syntax was also supported on the left-hand side of an assignment, so

10 LET A£ = "FOO"
20 LET A£ ,2= "BAR"
30 PRINT A£

would print FBARO

  Arrays 

Support for handling arrays of data was relatively strong, with MAT statements able to read an entire array from DATA statements, and perform useful matrix 

Matrix most commonly refers to:

*  ''The Matrix'' (franchise), an American media franchise
** ''The Matrix'', a 1999 science-fiction action film
** "The Matrix", a fictional setting, a virtual reality environment, within  ''The Matrix'' (franchis ...
 operations such as  matrix addition,  matrix subtraction,  matrix multiplication, and finding the  inverse matrix for a square matrix 

In mathematics, a square matrix is a matrix with the same number of rows and columns. An ''n''-by-''n'' matrix is known as a square matrix of order  Any two square matrices of the same order can be added and multiplied. 

Square matrices are often ...
.

Example:

10 DIM A(3,3)
20 MAT READ A
30 DATA 1,1,2,1,0,2,0,2,1
40 DIM B(3,3)
50 MAT READ B
60 DATA 0,0,1,0,1,0,1,0,0
70 DIM C(3,3),D(3,3)
80 MAT C=A*B
90 MAT D=INV(C)
100 MAT PRINT D,



The output would be
2              2              1
1              -1             0
4              -3             -2

  Debugging 


SOBS had primitive debugging capabilities, limited mostly to the TRACE statement. TRACE ON would cause the interpreter to print each line number as it was executed.

 References





{{DEFAULTSORT:Southampton Basic System
 BASIC interpreters
 ICL programming languages
 Science and technology in Hampshire
 University of Southampton
 BASIC programming language family