[BBC-Micro] Envelope command in Basic V

Sprow info at sprow.co.uk
Sun Nov 19 17:50:14 GMT 2006

As Richard points out the keyword seems to have been quietly omitted from
the BASIC user manual, though it is indeed in the interpreter (as "HELP E")

In article <45608EE2.5010701 at starfleet.homeunix.net>,
   Richard Gellman <splodge at starfleet.homeunix.net> wrote:
> Minor update... I've just tried the ENVELOPE statement on my A4000 with 
> 14 dummy parameters. It doesn't do anything (as per the wikipedia 
> article), but does not error either. 

Just to avoid any further myth creation, the ENVELOPE keyword *does* do
something in BASIC V: it evaluates the 14 parameters and stuffs them in a
block and calls OS_Word with R0=8.

On a normal RISC OS system this appears to do nothing, but someone could
write a module to catch OS_Word 8 and implement it.

Furthermore, when running in my ARM 7 coprocessor the OS_Word is passed to
the host allowing you to make all the retro envelope sounds you could want.
Similarly SOUND with 4 parameters is issued as an OS_Word 7,

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