Try 1970. https://www.vintagecomputermusic.com/notran_system.php
I worked in the same (computer graphics) lab with Hal. He wrote the seminal book on microprocessor generated music and later worked at Kurzweil. Marc Howard On Tue, Jul 11, 2023 at 1:10 PM Martin Bishop via cctalk < cctalk@classiccmp.org> wrote: > For info on DAC internals, have a look at > https://www.analog.com/en/education/education-library/analog-digital-conversion-1986.html > Part 2 details basic A/D & D/A architectures > > Current output converters are: > - less common than voltage output DACs > - and, if a ladder conversion architecture is used, lurking inside voltage > output DACs behind a transimpedance amplifier (I to V converter) > > I would be very surprised if the AAV11 does not output buffered volts > > Lots of other good reference material on analog.com, TI.com is also worth > a look > > Martin > > PS Most contemporary audio work uses SigmaDelta converters, see e.g. > Analog Devices AN-283 and MT-022 > > -----Original Message----- > From: Douglas Taylor via cctalk [mailto:cctalk@classiccmp.org] > Sent: 11 July 2023 17:29 > To: Mike Katz via cctalk <cctalk@classiccmp.org> > Cc: Douglas Taylor <dj.tayl...@comcast.net> > Subject: [cctalk] Re: Talking PDP11 > > The DACs on the AAV11-C board are not marked in any revealing way. I > think they are Burr Brown DAC80, 24 pin, but I'm not sure. I wasn't sure > if they were working and was looking for a replacement. > > Looking at the spec sheets DAC's seem to come in Voltage or Current > versions. Life got more complicated. > > This started out as a simple exercise into verifying the AAV11-C operation > using PDP11GUI to program up a basic program to run all the codes thru the > DAC. It worked, got a ramp out. Now, I'm starting to look at the KWV11-C > and how to use that to send values to the DAC at a controllable rate. > > Doug > > ------------------ > > On 7/11/2023 11:41 AM, Mike Katz via cctalk wrote: > > I originally used R-2R DACs but I was lucky enough to be able to buy a > > couple of DAC08 chips at Radio Shack and built a circuit using 74LS244 > > latching buffers so that I could drive both channels of a single 8-bit > > parallel port and 2 extra control lines (Select and Strobe). > > > > On 7/11/2023 6:43 AM, ste...@malikoff.com steven--- via cctalk wrote: > >>> On 07/10/2023 11:31 PM AEST Mike Katz via cctalk > >>> <cctalk@classiccmp.org> wrote: > >>> Way back in the 80's I was able to do stereo 4 part harmony on a 2 > >>> MHZ > >>> 6809 using two 8-bit D/A converters. > >> Much the same here. I recounted this on VCFed a few months ago about > >> building a simple 2-chip 8-bit ladder DAC with one-transistor > >> amplifier for my Applied Technology DG680 S100 machine back in the > >> early 80s from this absolutely excellent BYTE article on how to do > >> polyphonic synthesis on a microcomputer (KIM-1): > >> > >> https://archive.org/details/byte-magazine-1977-09/page/n63/mode/2up > >> > >> A schoolfriend who had an Apple ][ and had not done any Z80 machine > >> code before asked for me to hand him my Zaks book, upon which he > >> wrote out one attempt in Z80, crossed it out and wrote a second > >> version. Which worked perfectly. For the music piece I got it to play > >> four-voice polyphony after painstakingly encoding Bach's Praeludium > >> in C Major from my mothers' collection of piano music scores. > >> > >> A few years ago I had thoughts about porting the 6502 code to the > >> PDP-11 and use the same sort of ladder DAC. Not sure if the slimline > >> 11/05 would be fast enough for anything too high frequency, but if it > >> was, the slimline 05's power supply could then temporarily come out > >> and be perhaps be powered off some beefy batteries in that space, > >> along with a small 1970s transistor amp and 1970s headphones topped > >> off with a leather shoulder strap to lug it around like a giant Walkman. > > > >
