Re: Sound Input on IIGS
                                       
   From: dempson@actrix.gen.nz (David Empson)
   Reply to: David Empson
   Date: Tue, 06 Aug 1996 01:02:22 +1200
   Organization: Empsoft
   Newsgroups:
          comp.sys.apple2
   Followup to: newsgroup(s)
   References:
          <4tsc5k$r7l@news.vanderbilt.edu> 
          <3AUG199606073181@vax2.concordia.ca> 
          <4u3tos$ian@news.vanderbilt.edu>

In article <4u3tos$ian@news.vanderbilt.edu>, lesherjt@vuse.vanderbilt.edu
(Tilghman Lesher) wrote:

>Mitchell Spector (spec@vax2.concordia.ca) wrote:
>: In article lesherjt@vuse.vanderbilt.edu (John Lesher) writes...
>: >
>: >       How can I get the IIGS to sample sound?  When I had
>: >my //e, I had this nifty little program to sample sound via
>: >the cassette port, but the IIGS has no cassette port.  Is
>: >there a simple method?  Or must I buy a peripheral card?
>
>[snip]
>
>:    As I mention above, sound sampling is built-in to the chip (ADC),
>: but Apple didn't add any conventional way to plug in your sound source.
>: They did however provide a set of molex I/O pins. You basically have
>
>[snip]
>
>Where on the motherboard are these pins and (if > 2) what are the
>pinouts?

It is the 7-pin molex connector in the lower right corner of the
motherboard, next to the Ensoniq.  All stereo cards plug into this
connector.

Most of the pins are used for sound output and associated demultiplexing.
Pin 1 is the sound input and pin 2 is analog ground.  (Pin 1 is the one
closest to the back of the computer, right next to the legend "J25" on the
ROM 1 motherboard.)

The sound input expects a signal which has a maximum range of 2.5V peak to
peak.  The input impedance is 3000 ohms.

I'm not all that clear on audio impedances and voltages, so I'm not sure
if it is safe to connect anything directly to this pin.  It may be
necessary to use a simple amplifier circuit to handle impedance matching.

Can anyone elaborate on this?

--
David Empson
dempson@actrix.gen.nz
Snail Mail: P.O. Box 27-103, Wellington, New Zealand