Hello
First of all I say again this no joke!!
I will never post anything the 1st of april...
except jokes!! :-D
@Thomas I think you should update your "world view"!
I posted the same message in comp.sys.amiga.hardware and got a reply from Dave Haynie!!!
Here is what he writes:
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> I am speaking about Paula direct coding, no AHI.
>According to the Hardware Ref. Manual (HRM) audio channels 0 and 3 are
>associated to the Right Channel (R) while 1 and 2 to the Left one (L).
That's the plan...
> 1) A2000 works as described in HRM
I did it pretty much the way the A1000 did it, though using George
Robbins' cheaper anti-imaging filter.
> 2) A500, A600 and A1200 do the opposite, i.e. channels 0,3 come from L
>while 1,2 come form R
Sounds like they screwed these up. I never checked, myself.
> 3) A4000D is tricky.
> Here 0,3 come from the jack whose physical position, if one stands in
>front of the front panel of the case, is right. Such jack is colored in red, which usually means right.
>However, at least on my case, the jack is labelled "L" !!!!
> Of course 1,2 come from the left positioned jack, colored white BUT
>labelled "R"
Sounds like the motherboard is built correctly, the case labelled
incorrectly.
> 4) A4000T is even more tricky. I recall that on A4000T there is a
>video/audio module which is a daughterboard,
I actually worked a little on the A4000 audio, so let's see. The
daughterboard is easy to explain: we were moving toward the use of
more standard PC casework, but ATX had not yet been invented. So where
do you put the ports? You put 'em on plug-in cards, of course.
> So here 0,3 come from the jack physically to the right, colored red and
>referenced as "right" in the manual (on the board there is no
> label).
> However, the A4000T has also a headphone connector. And if I use a
>headphone, then I hear channels 0,3 coming from the left!!!
Sounds like that's done wrong. The built-in speaker, of course, is
mono.
> Q3: Suppose I want to produce sound from a specified jack. For example I
>could have a program playing a sound with a "left/right balance" volume
>command:
I don't think left/right balance was major concern. No one imagined
you'd want to allocate two Paula channels for one stereo channel,
simply to allow for balance. This was actually addressed, poorly, in
AAA, where you could select L or R for each of the 8 audio channels.
But not a L/R mix, which would have been the right answer.. and fairly
easy to do, too.
> a) detect which Amiga model the program is running on (not easy, since
>it's not the question of detecting CPU or the chipset, but the motherboard!)
> b) choose one, I would say channels 0,3 coming from Left, since
>A500/A1200/A600 are the majority of Amiga models and assume the users of
>other models swap the connection of the audio jacks
> c) other ideas??
First time you run the program, play a sound on what you think is the
left channel. As the user "do you hear this on the left or the right".
Store that in your PROGDIR: and adjust accordingly. This way, you also
address the users of properly (or non-ambiguously) speced audio jacks
who've managed to wire them backwards, anyway.
>Q4: I can't see any rationale behind the choice of using different
>assignments on different models! Do you see any good reason?
Someone make a mistake, and copied it forward to subsequent models
("someone" would probably have to be or George, though I'm not sure,
Greg may have done the headphone jack in the A4000T, or it may have
been me -- I was mainly doing AAA and other "advanced" stuff in the
A4000 days, but I did help out on Zorro and some of the analog audio
stuff).
Dave Haynie | Chief Toady, Frog Pond Media Consulting
dhaynie@jersey.net| Take Back Freedom! Bush no more in 2004!
"Deathbed Vigil" now on DVD! See
http://www.frogpondmedia.com :-D :-D
