Southampton BASIC System: Difference between revisions

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{{One source|date=December 2023}}

{{see also|SOB (disambiguation)}}

'''Southampton BASIC System''' (SOBS} was a dialect of the [[BASIC]] programming language developed for and used on [[ICT 1900]] series computers in the late 60s and early 70s; it was implemented under the [[MINIMOP]] operating system at the [[University of Southampton]].<ref>

{{Use dmy dates|date=August 2021}}

{{cite web

'''Southampton BASIC System''' ('''SOBS}''') was a dialect of the [[BASIC]] [[programming language]] developed for and used on [[ICT 1900 series]] series computers in the late 60s1960s and early 70s1970s; it was implemented as an incremental [[BASIC interpreter]] under the [[MINIMOP]] operating system at the [[University of Southampton]].<ref>

| last = Rees

{{cite webjournal

| first = M.J.

| lastlast1 = Rees

| firstfirst1 = M.J.

| last2 = Oppenheimer

| first2 = A.W.

| title = SOBS -– an incremental BASIC system

| workjournal = Software: Practice and Experience

| publisher = Wiley InterScience

| date = {{date|21 January 1977}}

| volume = 7

| url = http://www3.interscience.wiley.com/journal/113444749/abstract?CRETRY=1&SRETRY=0

| issue = 5

| pages = 631–643

| url = http://www3.interscience.wiley.com/journal/113444749/abstract?CRETRY=1&SRETRY=0

| archive-url = https://archive.today/20130105083634/http://www3.interscience.wiley.com/journal/113444749/abstract?CRETRY=1&SRETRY=0

| url-status = dead

| archive-date = 5 January 2013

| format =

| doi = 10.1002/spe.4380070508

| s2cid = 33989728

| accessdateaccess-date = {{date|18 May 2009}}

}}</ref>

| url-access = subscription

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

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

== Language characteristics ==

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|-

| <code>PRINT</code>

| Output to the teletypeTeletype

|-

| <code>READ ''var''...</code>

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=== Variables ===

[[Variable (programming)|Variable]] 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 (<code>&pound;£</code>) symbol.

=== Functions ===

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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

<syntaxhighlight lang="basic">

10 LET A£ = "FOO"

2010 PRINTLET A£[2,3] = "FOO"

3020 PRINT A£[2,3]

</syntaxhighlight>

would print <code>OO</code>

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

<syntaxhighlight lang="basic">

10 LET A£ = "FOO"

2010 LET A£[2,2] = "BARFOO"

1020 LET A£[2,2] = "FOOBAR"

30 PRINT A£

30 PRINT A£

</syntaxhighlight>

would print <code>FBARO</code>

=== Arrays ===

Support for handling arrays of data was relatively strong, with <code>MAT</code> statements able to read an entire array from <code>DATA</code> statements, and perform useful [[matrix (mathematics)|matrix]] operations such as adding[[matrix oraddition]], multiplying two[[matrix matricessubtraction]], or[[matrix evenmultiplication]], and finding the [[multiplicative inverse matrix]] offor a [[square matrix]].

Example:

<syntaxhighlight lang="basic">

10 DATA 0,0,1,0,1,0,1,0,0

2010 DIM A(3,3)

3020 MAT READ A

4030 DATA 21,41,32,-1,0,-2,10,-42,51

5040 DIM B(3,3)

6050 MAT READ B

1060 DATA 0,0,1,0,1,0,1,0,0

70 DIM C(3,3),D(3,3)

80 MAT C = A * B

9080 MAT PRINT C,=A*B

90 MAT D=INV(C)

A contains

100 MAT PRINT D,

<math>\begin{pmatrix}

</syntaxhighlight>

0 & 0 & 1 \\

{|

0 & 1 & 0 \\

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

1 & 0 & 0

|<math>\begin{pmatrix}

1 & 1 & 2 \\

0 1 & 0 & 12 \\

0 & 2 & 1

\end{pmatrix}</math>

|-

, B contains

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

|<math>\begin{pmatrix}

2 & 4 & 3 \\

-1 0 & 0 & -21 \\

0 & 1 & -4 &0 5\\

1 & 0 & 0

\end{pmatrix}</math>

|-

, C contains

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

|<math>\begin{pmatrix}

1 & -4 & 5 \\

2 & -1 & 0 & -21 \\

2 & 40 & 31 \\

1 & 2 & 0

\end{pmatrix}</math>

|-

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

|<math>\begin{pmatrix}

2 & 42 & 31 \\

0 1 & -1 & 0 \\

4 & -3 & -2

\end{pmatrix}</math>

|}

The output would be

This is the output:

12 -4 5 2 1

-1 0 -21 0

24 4 -3 -2

== Debugging ==

{{expand- section|date=May 2009}}

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

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{{Reflist}}

{{ICL hardwareBASIC}}

{{DEFAULTSORT:Southampton Basic System}}

[[Category:BASIC interpreters]]

[[Category:ICL programming languages]]

[[Category:Science and technology in Hampshire]]

[[Category:University of Southampton]]

[[Category:BASIC programming language family]]