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From: jfreem@uncecs.edu (Joe Freeman)
Newsgroups: comp.sys.next
Subject: Re: Access to sound port from DSP?
Message-ID: <1991Mar26.123538.29687@uncecs.edu>
Date: 26 Mar 91 12:35:38 GMT
References: <1991Mar24.231144.19341@nntp-server.caltech.edu> <38fl02Ef06Hs01@JUTS.ccc.amdahl.com> <1991Mar25.113606@ecn.purdue.edu>
Organization: UNC Educational Computing Service
Lines: 39

In article <1991Mar25.113606@ecn.purdue.edu> cyliax@ecn.purdue.edu (Ingo Cyliax) writes:
>After pooring through all the literature on the sound and mic. ports
>and the DSP that I can find, I have come to the conclusion that there
>is no direct connection from the CODEC and the DAC to the DSP. I think
>it's all done with the DMA controller and the host port on the DSP. Is
>this correct ?
>
Yep. (I think you men pouring, unless you were commenting on the docs)
The CODEC and the DACs are accesed via the DMA or host processor.  You
can request a stream from the CODEC or to the DACs and the driver
will do all the buffer management.  All data into and out of the DSP
goes through the host port.

>Also, I haven't found anything  on wether the serial ports from the DSP
>are used for anything internal on the NeXT. Is there a diagram or technical
>description of the hardware layout of the NeXT DSP, sound system and the
>DMA controller ? 
You don't really  need to know the hardware layout but there should
be a data diagram for it.  Once again, the driver takes care of any
communications.  You have two choices.  The host program can do
practicly nothing and just set up the streams or it can manage each individ.
buffer.
>
>Has anyone thought of using the high speed serial ports from the DSP for
>anything besides hooking up CODECs, A/D or DACs ? One could design a serial
>port multiplexer or some high speed data channel to some other systems.
>ISDN anyone ? What's the max. DMA bandwidth between the DSP and host 
>memory ? 
I've done a 10 band graphic equalizer (moto app note port) and the 
PowerGlove driver.  All via the external port.  The DSP is the only way
to guarentee real time performance.  Because you own it.  I've heard the
max bandwidth is 2.5MB per sec but that doesn't leave any time for 
doing any filtering.  The digital ears runs at 160K byte per sec.
>

-- 
Joe Freeman	jfreem@uncecs.edu
The opinions espressed here are my own and are not shared by my employer  or
anyone else I know of.  Flames can be mailed to me or routed to /dev/null.