Re: Apple II Speaker

["M. Pender" <mpender@hotmail.com>]

Bill Garber <willy46pa@comcast.net> wrote in message
VpydneT1xtrtRlqiRVn-jw@comcast.com">news:VpydneT1xtrtRlqiRVn-jw@comcast.com...
>
> Sure. What I hope to accomplish is to separate
> the sound signal into high and low. I found a
> circuit that will do this. I also think that
> instead of that, being that the highs and lows
> would be unequal, that a simple flip-flop of the
> signal, first to speaker 1 and then to speaker 2,
> would give me closer to the real result I am
> looking for. I have some 556 timers and a bunch
> of LM324 quad Op-Amps that I will play with to
> see if I can get it to play for a few mS thru
> speaker 1 and then a few mS thru speaker 2.
> Should prove very interesting at the very least.
> Stereo? No. Improved game sounds? Maybe. Just for
> fun is all. For now. I'm tackling a new Apple II
> frontier. Slotless interfacing. It is showing me
> quite a bit about how the Apple II works internally
> and getting past the hurdles that slots take care
> of for you is intriguing. My goal is to eventually
> be able to interface devices to the IIc family.
> This is no easy task, as many of the devices that
> are already interfaced do not work exactly the
> same as the slotted IIs, although they are nearly
> 100% compatible. I say nearly only because I've
> heard that some programs don't run properly even
> though they do run. I hope to have a couple things
> working by next KFest, giving me more reason to
> attend. I just hate coming out with nothing to show
> everyone. ;-) Anyway, This speaker thing is one of
> the simpler things I'm messing with, no biggie.
> Just something to play around with when I get tired
> of working on the real stuff. Thanks for any help
> you can offer. BTW, glad to hear that you got the
> network up and running.
>

Bill, there's a trick I used to use that might help.  If you want to know
what tones are being generated by calls to the ROM sound routine, it is
possible to replace the routine on an Apple II+, IIe, IIc, or IIgs as long
as it has at least 64k of memory.

The idea is to save a copy of the Applesoft language to disk, modify the
code on disk, rename the file "intbasic" and then use Loader.obj0 to load
the code into the language card.

Then when you type "INT", instead of changing over to integer basic, you
will change over to your modified version of Applesoft.  Its also possible
to do the same thing with memory moves, but I don't recall the sequence of
softswitches.

Anyhow, it would allow you to trap all calls to the sound generation routine
in ROM, as well as the parameters passed to the routine.

Please let me know if this is not an adequately clear description.

- Mike