Date   : Sun, 19 Nov 2006 17:50:14 +0000 (GMT)
From   : info@... (Sprow)
Subject: Envelope command in Basic V

Hi,
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")
shows.

In article <45608EE2.5010701@...>,
   Richard Gellman <splodge@...> 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,
Sprow.