Editing BBC BASIC (section)

===Acorn Archimedes (RISC OS)===
{{Main|RISC OS}}
With the move to the 32-bit [[ARM architecture|ARM]] CPU and the removal of the 16&nbsp;KB limit on the BASIC code size many new features were added.<ref>
{{Cite newsgroup
| title=BASIC V 1.02 versus 1.04 changes (for Richard LLoyd!)
| author=Roger Wilson
| date=3 July 1989
| newsgroup=eunet.micro.acorn
| message-id=807@acorn.co.uk
| url=https://groups.google.com/group/eunet.micro.acorn/browse_thread/thread/35385e5c11376a79/
| access-date=14 June 2011}}
</ref> BASIC V version 1.04 was 61&nbsp;KB long. Current{{When|date=December 2023}} versions of RISC OS still contain a BBC BASIC V interpreter. The source code to the [[RISC OS]] 5 version of BBC BASIC V has been released under the Apache 2.0 license by [[RISC OS Open]].

Amongst the new commands and features supported were:

* <code>[[While loop|WHILE-ENDWHILE]]</code>
* <code>IF-THEN-ELSE-ENDIF</code>
* <code>CASE-OF-WHEN-OTHERWISE-ENDCASE</code>,
* <code>RETURN</code> parameters in procedures,
* local arrays,
* procedure libraries (<code>LIBRARY</code>,<code>INSTALL</code> and <code>OVERLAY</code>),
* <code>LOCAL DATA</code> and <code>LOCAL ERROR</code> handlers,
* a relative <code>RESTORE</code>,
* [[Array data structure|array]] operations,
* new operators,
* <code>STEP TRACE</code>,
* Commands for the new sound system, mouse, graphics.

The graphics commands were entirely [[backwards compatible]], the sound less so; for example, the <code>ENVELOPE</code> keyword from BASIC V onwards is a command that takes fourteen numeric parameters and effectively does nothing— as in older versions, it calls OS_Word 8, but that does nothing on RISC OS.<ref>{{Cite web | url=http://mdfs.net/Archive/BBCMicro/2006/11/19/185014.htm | title=Subject: Envelope command in Basic V }}</ref> The in-line 6502 assembler was replaced by an [[ARM architecture|ARM]] assembler. BASIC V was said, by Acorn, to be "certainly the fastest interpreted BASIC in the world" and "probably the most powerful BASIC found on any computer".

BASIC VI is a version of BASIC V that supports [[IEEE 754]] 8-byte format real numbers, as opposed to the standard 5-byte format introduced in BASIC I.

BBC BASIC V and VI were delivered as standard on the [[Acorn Archimedes]] and the [[RiscPC]]. A version of BBC BASIC V was also available to run on the [[Tube (BBC Micro)|ARM second processor]] for the BBC Micro.

A compiler for BBC BASIC V was produced by Paul Fellows, team leader of the Arthur OS development, called the Archimedes BASIC Compiler and published initially by DABS Press.{{citation needed|date=December 2011}} ABC was able to implement almost all of the language, with the obvious exception of the EVAL function, which inevitably required run-time programmatic interpretation. As evidence of its completeness, it was able to support inline assembler syntax. The compiler was written in BBC BASIC V. Many applications initially written to run under the interpreter benefitted from the performance boost that this gave, putting BBC BASIC V on a par with other languages for serious application development.