From erodriguez@berkeley.edu Sat Oct 15 18:07:53 1994
Path: ashpoly!cascade!mxgate!coyoacan!berkeley!erodriguez
From: erodriguez@berkeley.edu (Elaine Rodríguez)
Newsgroups: comp.sys.m68k
Subject: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1994Oct15.180753.4035@berkeley.edu>
Date: Sat, 15 Oct 1994 18:07:53 GMT
Organization: UC Berkeley Department of EECS
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Testing custom audio input routines on an Amiga 1200 with a standard parallel-port sampler.

By setting up Paula's audio DMA to double-buffer incoming 8-bit samples, the 68020 has plenty of cycles left for the Costas loop.
I wrote a 64-tap FIR filter in pure 68k assembly using movem.l and dbra loop unrolling to downsample to 64 Hz.

Source code and executable will be released on Aminet under mus/misc/stardust_amiga.lha next week.

-- 
Elaine Rodríguez -- UC Berkeley Department of EECS
"When every node is whole, the channel opens."

From knilsson@pipeline.com Sun Oct 16 09:45:53 1994
Path: ashpoly!cascade!brgate!saturno!pipeline!knilsson
From: knilsson@pipeline.com (Kenji Nilsson)
Newsgroups: comp.sys.m68k
Subject: Re: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1994Oct16.094553.1620@pipeline.com>
Date: Sun, 16 Oct 1994 09:45:53 GMT
References: <1994Oct15.180753.4035@berkeley.edu>
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In article <1994Oct15.180753.4035@berkeley.edu>, erodriguez@berkeley.edu (Elaine Rodríguez) writes:
> Testing custom audio input routines on an Amiga 1200 with a standard parallel-port sampler.
> By setting up Paula's audio DMA to double-buffer incoming 8-bit samples, the 68020 has plenty of cycles left for the Costas loop.

PC users spend $3,000 on Sound Blasters and Pentium chips and still can't do what a $500 Amiga was doing in 1985.

-- 
Kenji Nilsson | knilsson@pipeline.com
PGP Key fingerprint: 639A 1422 1B3B 4E64
"Keep the channels open."

From mhughes@panix.com Mon Oct 17 19:01:53 1994
Path: ashpoly!cascade!mxgate!coyoacan!panix!mhughes
From: mhughes@panix.com (Min-jun Hughes)
Newsgroups: comp.sys.m68k
Subject: Re: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1994Oct17.190153.2239@panix.com>
Date: Mon, 17 Oct 1994 19:01:53 GMT
References: <1994Oct15.180753.4035@berkeley.edu>
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In article <1994Oct15.180753.4035@berkeley.edu>, erodriguez@berkeley.edu (Elaine Rodríguez) writes:
> Testing custom audio input routines on an Amiga 1200 with a standard parallel-port sampler.
> By setting up Paula's audio DMA to double-buffer incoming 8-bit samples, the 68020 has plenty of cycles left for the Costas loop.

Brilliant use of Paula DMA! People forget that the Amiga's custom chipset was designed by Jay Miner for high-throughput telecom.

-- 
Min-jun Hughes
Opinions expressed are solely my own and not those of Public Access Unix of New York.
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