Re: How is the IIgs beep generated?

[Mitchell Spector <mitch2gs@hotmail.com>]

"Michael J. Mahon" <mjmahon@aol.com> wrote:

>Mitchell Spector wrote:
>>     Hmm, tried it on my Apple IIGS a moments ago (would have 
>> tried it on the Apple IIc I rescued from a recycling center a few
>> weeks ago, but I just put it into storage with my other Apple II's).
>> 
>>     Well, it's quite similar to the IIGS "bonk" yet not at all the 
>> same. It still has that very distinctive Apple II speaker sound.
>> Difficult to describe, but I hear "Bonkzzzzzzt", "Bonkzzzzzt"
>> rather than a crisp and very defined "Bonk". 
>> 
>>     The more I listen to the GS's bell, the more I'm convinced
>> it's not something that can be reproduced on an Apple IIe.
>> Example, set the pitch in the Sound Control Panel to the
>> highest level. Try listening to it over and over, I've never
>> in all my years of Apple II gaming, programming and tinkering
>> heard a sound like that from the speaker (excluding, say, 
>> digitized audio, though even then it wouldn't be as clear).
>
>I don't know what parameters you were using, but...

    Parameters? All I did was download the Applesoft BASIC
program you wrote (the second revision) and ran it as-is on 
my Apple IIc (managed to dig it out over the weekend and
had a listen). It runs through the sound scale from high to 
low. I didn't play with any of the parameters.

>I just happened to get access to a IIgs this weekend.
>
>The correct parameters for the default IIgs "bonk" are:
>
>POKE 6,83
>POKE 7,2
>CALL 768
>
>That reproduces it quite well.  The volume is about 2/3 the max
>volume of a raw beep, but the ear doesn't really care.  ;-)

    It's a similar approximation of the GS "bonk" bell (especially
the lower tones), but certainly not the same. :)

    I'm still curious how the tone is produced. Maybe it's standard 
speaker toggling that is then filtered or enhanced somehow using
something unique to the GS's audio circurity?

Mitchell Spector