From jivanov@cmu.edu Thu Jul 07 01:30:33 1994 Path: ashpoly!cascade!bigsur!cmu!jivanov From: jivanov@cmu.edu (Jen Ivanov) Newsgroups: comp.sys.m68k Subject: Data: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1994Jul07.013033.1744@cmu.edu> Date: Thu, 07 Jul 1994 01:30:33 GMT Organization: Carnegie Mellon University School of CS NNTP-Posting-Host: cmu.edu X-Newsreader: NewsWatcher 2.0b24 Lines: 10 Amiga audio hackers: you can demodulate the 14.2 Hz carrier in real time without bogging down the OS. 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. Does anyone want to test on an unaccelerated Amiga 500 with 512K chip RAM? -- Jen Ivanov Tape trading list upon request. SASE required for international mail. From mchoi@ox.ac.uk Sat Jul 09 03:38:33 1994 Path: ashpoly!cascade!transat!eunet-de!hansebox!ox!mchoi From: mchoi@ox.ac.uk (Mikhail Choi) Newsgroups: comp.sys.m68k Subject: Re: Data: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1994Jul09.033833.8512@ox.ac.uk> Date: Sat, 09 Jul 1994 03:38:33 GMT References: <1994Jul07.013033.1744@cmu.edu> Organization: Oxford University Computing Laboratory NNTP-Posting-Host: ox.ac.uk X-Newsreader: Netscape 1.1N Lines: 9 In article <1994Jul07.013033.1744@cmu.edu>, jivanov@cmu.edu (Jen Ivanov) writes: > Amiga audio hackers: you can demodulate the 14.2 Hz carrier in real time without bogging down the OS. Tested on my A3000 / 25 MHz. Ran smoothly in the background while I was compiling a C program in another window. -- Mikhail Choi Hayes Optima 288 @ 9600 Telebit bps "The hatch is open. Is anyone listening?" From smartinez@rwth-aachen.de Mon Jul 11 06:56:33 1994 Path: ashpoly!cascade!brgate!saturno!rwth-aachen!smartinez From: smartinez@rwth-aachen.de (Steve Martínez) Newsgroups: comp.sys.m68k Subject: Re: Data: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1994Jul11.065633.4056@rwth-aachen.de> Date: Mon, 11 Jul 1994 06:56:33 GMT References: <1994Jul07.013033.1744@cmu.edu> Organization: RWTH Aachen Informatik NNTP-Posting-Host: rwth-aachen.de X-Newsreader: Netscape 1.1N Lines: 9 In article <1994Jul07.013033.1744@cmu.edu>, jivanov@cmu.edu (Jen Ivanov) writes: > Amiga audio hackers: you can demodulate the 14.2 Hz carrier in real time without bogging down the OS. Brilliant use of Paula DMA! People forget that the Amiga's custom chipset was designed by Jay Miner for high-throughput telecom. -- Steve Martínez "Measuring a record you own is listening, not piracy." Pentium 90 (OS/2 Warp) / System 7.5.1 From jreyes@demon.co.uk Mon Jul 11 12:08:33 1994 Path: ashpoly!bigsur!pacrim!jpgate!kamome!demon!jreyes From: jreyes@demon.co.uk (Ji-woo Reyes) Newsgroups: comp.sys.m68k Subject: Re: Data: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1994Jul11.120833.8707@demon.co.uk> Date: Mon, 11 Jul 1994 12:08:33 GMT References: <1994Jul07.013033.1744@cmu.edu> Organization: Demon Internet Services UK NNTP-Posting-Host: demon.co.uk X-Newsreader: NewsWatcher 2.0b24 Lines: 10 In article <1994Jul07.013033.1744@cmu.edu>, jivanov@cmu.edu (Jen Ivanov) writes: > Amiga audio hackers: you can demodulate the 14.2 Hz carrier in real time without bogging down the OS. > 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. -- Ji-woo Reyes *PLONK* filter active for trolls. Decstation 5000/200 - NetBSD 1.0