Re: Working on a //+

[mjmahon@aol.com (Michael J. Mahon)]

Ralph Glatt wrote:

>Okay, I tried running the //+ without the 1 meg memory card in it. The
>clicking, and the stop/start thing vanished, but now I think there's
>something wrong with my Disk ][ drives. I get the Apple][ prompt, but
>the drive just spins. Will a cleaning do, or will I have to adjust
>something in the drives? I have two, and I tried them both, got the
>same thing each time.

(You'll have to pardon me if I'm supposed to remember something
you posted earlier about this--I don't.)

Since it is unlikely that your RAM card contains a short (but not
impossible), I would interpret this as a power supply problem.  Your
poser supply probably needs a capacitor (or two) replaced to get
its current capacity back to where it should be.  The RAM card is
now pushing it beyond what it can supply and maintain voltage
regulation, so it is shutting down and restarting--clicking.

WRT your spinning disk, that's what it _should_ do if it cannot
read an OS from the disk.  Check the disk for validity, the drive
heads for dirt, and the drive for speed--in that order.  You'll have
a much easier time if you can get at least one drive/disk combo
to work, since you can then load diagnostic software.

>By the way, the reason I want to get this thing running is so I can
>record a few sound effects, so some programmer can use them. After
>that, I'm going to use the motherboard as the brains in a robot I've
>been promising myself.

Sound on the 8-bit Apple II's is a pet topic of mine.  ;-)

If you want to digitize sounds on an 8-bit (non-IIgs) Apple, you'll
need a fairly fast A/D converter and some software to use it.
Good quality requires at least 8KHz sampling for speech (telephone
quality) and 11KHz sampling for music (AM radio quality).  An
unaided Apple II can only digitize sound to 1-bit accuracy (through
the cassette input), and the result is _extremely_ gravelly sound.

Playing back sound on an 8-bit Apple is not so limited, although
the most common use of the speaker provides only 1-bit playback,
for the same rotten quality noted above.  I've written a high-quality
PWM DAC in software for 1MHz Apples that delivers true 5-bit
sampled sound quality at 11KHz sample rate.  The playback is
done with 2x oversampling (22KHz) to raise the "carrier" above
most people's hearing.  The effect is astounding to anyone who
is familiar with typical Apple II sound--it makes it sound like a
IIgs or a Mac!  In fact, you should really hook up a better external
speaker or use headphones to get the full effect.

The downside is that the standard memory of an Apple can only
hold about 1.8 seconds of 11KHz sampled sound (with room for
some program code), but that is plenty long enough for quotes
like "I'll be back!" and "Now for something completly different."

RAM disk can be used to swap a bunch of sounds quickly.  Or if
you can tolerate a little "pop" every couple of seconds, there's a
program called "IIsound" that uses my player to play longer sounds
out of AuxMem.

My own program, SoundEditor 2.2, is a moderately capable
oscilloscope-display sound editor, with support for 2:1 ADPCM
compression on disk, is available at my web page (below).

-michael

 Email:  mjmahon@aol.com
 Home page:  http://members.aol.com/MJMahon/