Re: Working on a //+

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

Ralph Glatt replied:

>Hi, Mike, thanks for responding! Yes, I earlier posted about a problem
>with my Apple ][+. I did take apart the power supply, but I didn't see
>anything leaking. I'll pull it apart again and give it a thorough
>looking over, though. As for the cards, I had a 16k card plugged into
>slot 0, the 1 meg RAM card in slot 3, and the floppy drive card in
>slot 6.  With this setup, I had the clicking problem. I took out the 1
>meg card and the problem vanished. Tomorrow, when I check out the
>power supply, I'll take along a DOS 3.3 master diskette and a cleaning
>kit. With my luck, a capacitator WILL be out, and I won't be able to
>tell which one!

You won't, in general, be able to judge the health of a capacitor by
sight.  It can look perfect and be dried-out.  The easiest way to
"test" a capacitor for low capacitance is to "bridge" it with a known
good capacitor of similar or better voltage and capacitance ratings.
In the power supply, this should be done carefully, and with clip
leads.  If the supply works with a cap bridged, that cap needs to
be replaced.

>As for the sound, I have an old program that digitizes sound from the
>cassette port. No, it won't sound great, and the sound clips won't be
>long, but they don't need to be. What I'd really like to do, if I ever
>get my ambition up, is to make a Doom clone for the Apple //. No way
>will it be as good as Wolfenstein 3D, but I don't intend it to. It'll
>be made for a //c, or a //e with 128k and a mouse card. (A REALLY
>ambitious project!)What matters most is I'm having fun with it.

Good lick--getting playable speed will be a problem--even without
sound...  And you will not be able to do _anything_ else while a
sound is being played--it takes the Apple's full attention to do the
precise timing required to control the speaker.  It _is_ possible to
play very short sounds interleaved with game play, to make game
sounds, for example.  Using a softDAC player permits game sounds
to be anything, not just typical speaker noises.

If you're satisfied with 1-bit samples (ugh!), then you can pack a lot
more samples into a given amount of RAM. Eight samples per byte
is straightforward, but run-length compression might get you even
more, if the sounds don't have much high-frequency content.

You will get much better sound quality, at the cost of space, by
sampling at 11.025KHz and 8-bits (mono, of course).  Most Macs
and any PC with a sound card can do this.  You should save the
sound samples in the "rawest" file format available, like .wav.  Avoid
compressed formats, which Apples tend to want to make.  The sound
file can then be moved to the Apple II and get it's .wav (or other) header
trimmed off in the editor, and you're ready to go.

You can also strip sounds from existing sound files, keeping the
chunks under the size limit for the Apple II.

-michael

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