Southampton BASIC System: Difference between revisions

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{{One source|date=December 2023}}

{{see also|SOB (disambiguation)}}

{{Use dmy dates|date=JanuaryAugust 20112021}}

'''Southampton BASIC System''' ('''SOBS''') was a dialect of the [[BASIC]] [[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]]<ref>

{{cite journal

| lastlast1 = Rees

| firstfirst1 = M.J.

| last2 = Oppenheimer

| first2 = A.W.

| title = SOBS -– an incremental BASIC system

| journal = Software: Practice and Experience

| publisher = Wiley InterScience

| date = 21 January 1977

Line 20 ⟶ 21:

| format =

| doi = 10.1002/spe.4380070508

| access-dates2cid = 18 May 200933989728

| access-date = 18 May 2009

}}</ref> and also ran under [[MAXIMOP]].

| url-access = subscription

}}</ref> and also ran under [[MAXIMOP]].

It was operated from a [[Teletype Corporation|Teletype]] terminal, though CRT terminals could also be used.

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Support for strings was more limited, with only one function, <code>LEN</code>, which returned the length of the string parameter. Sub-strings were supported with square brackets, so <code>A£[2,3]</code> referred to the sub-string of the string <code>A£</code> from the 2nd character to the 3rd character inclusive, so

<sourcesyntaxhighlight lang="basic">

10 LET A£ = "FOO"

20 PRINT A£[2,3]

</syntaxhighlight>

</source>

would print <code>OO</code>

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

<sourcesyntaxhighlight lang="basic">

10 LET A£ = "FOO"

20 LET A£[2,2] = "BAR"

30 PRINT A£

</syntaxhighlight>

</source>

would print <code>FBARO</code>

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Example:

<sourcesyntaxhighlight lang="basic">

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,

</syntaxhighlight>

</source>

{|

|<code>A</code> is read from the first <code>DATA</code> statement

|<math>\begin{pmatrix}

1 & 1 & 2 \\

1 & 0 & 2 \\

0 & 2 & 1

\end{pmatrix}</math>

|-

|<code>B</code> is read from the second <code>DATA</code> statement

|<math>\begin{pmatrix}

0 & 0 & 1 \\

0 & 1 & 0 \\

1 & 0 & 0

\end{pmatrix}</math>

|-

|<code>C</code> is calculated by multiplying <code>A</code> and <code>B</code>

|<math>\begin{pmatrix}

2 & 1 & 1 \\

2 & 0 & 1 \\

1 & 2 & 0

\end{pmatrix}</math>

|-

|<code>D</code> is calculated as the inverse of <code>C</code>

|<math>\begin{pmatrix}

2 & 2 & 1 \\

1 & -1 & 0 \\

4 & -3 & -2

\end{pmatrix}</math>

|}

The output would be

2 2 1

1 -1 0

4 -3 -2

== Debugging ==