From: aa700@cleveland.Freenet.Edu (Michael Current)
Newsgroups: comp.sys.atari.8bit
Subject: Re: Frequently-Asked Questions
Date: 8 Sep 1992 19:24:52 GMT
Organization: Case Western Reserve University, Cleveland, OH (USA)
Reply-To: aa700@cleveland.Freenet.Edu (Michael Current)
NNTP-Posting-Host: hela.ins.cwru.edu


In a previous article, UJ1G@DKAUNI2.BITNET ("Marek Tomczyk") says:

>
>Michael Current's FAQ contains:
>
>>      65XEM    65XE plus AMIE sound chip
>
>Hm, never heared of an AMIE sound chip. What is it exactly?
>Is it as good as the SID(?) inside the c=64?
>Is it possible to get the sound chip from somewhere and add it to
>my 130XE? How much does the AMIE costs?

That description of a 65XEM came from a 1985 issue of Antic (the issue
before the one with the flying 130ST on the cover.).  There happens to be
this issue of Byte from March 1986, with a 1040ST on the cover, which
contains an interview with Shiraz Shivji, Atari Corp. vice president of
research and development at that time.  Talking about future STs:

BYTE: What about sound capabilities?
Shivji: We had a project around here started during Alan Kay's tenure--a
chip called Amy.  And the ST was designed to have the Amy.  But the Amy did
not happen.  We had silicon, the first pass, in Octerober or
November[1985], and we had severe problems with it.  It was kind of an
orphan project.  And if you have a chip that has six or eight people who
have worked on it at different times, chances of the chip working are slim.
 But it's a good design.

BYTE: What does it do?  What's so special about it?
Shivji: The approach of others is that during horizontal-refresh time you
go out to some pace and put some memory out automatically , and that goes
through a DAC and you have sound.  Essentially you're sampling at 15.75
kHz, which is the typical frequency.  So it's like a digital tape recorder.
 You have a digitized sound and you're just putting it out.  And it needs
enormous amounts of memory.  The key is: How do you encode sound?  From an
information-theoretic point of view, there are two problems with this
papproach.  One is it's an anormous waste of memory.  Because you could
encode whatever sound you're going to play, as far as data is concerned in
a sound piece, the data rate is extremely low.  And doing it in the digital
tape recorder way, you're wasting an awful lot of bandwidth and a lot of
memory.  The second problem with other implementations is that you only
have 8 bits and it's not really that good.  Especially with CDs coming out.
     Amy was a chip that had 16 bits of information coming out.  So you
could have 96 decibels of range.  What you could hear!  Amy was a complete
digital sound chip.  It's called an additive-digital synthesizer.  It had
an adder and 64 independent oscillators.  It has a model for sound and you
feed it the parameters.  But if you do that you have to do an awful lot of
preprocessing.  We had hired a lot of people.  We had a VAX 780 devoted to
it.  We had equipment, fast floating-point array processors, and so on, to
analyze notes.  We would get a tape of piano playing and then the VAX would
analyze it and would take the Amy model and give the parameters..  To play
anything you only needed to have parameter tables and feed it to the chip.

The interview goes on a bit more, being even less informative.  It ends
with this ditty:

BYTE: So the Yamaha chip is in there just to give it the basic sound?
Shivji: Yes, just the basic sounds you need.  Though, of course, the ports
are very useful.

Sorry for any typos, I never looked up at the screen.  

I assume this Amy is the AMIE that was for a 65XEM as well.  
-- 
 Michael Current, Cleveland Free-Net 8-bit Atari SIGOp   -->>  go atari  <<--
   The Cleveland Free-Net Atari SIG is the Central Atari Information Network
      Internet: currentm@carleton.edu / UUCP: ...!umn-cs!ccnfld!currentm
     BITNET: currentm%carleton.edu@{interbit} / Cleveland Free-Net: aa700