You might try looking for Data Translation products. I know some of the later ad and da modules were made by them for DEC
On July 11, 2023 12:28:43 p.m. EDT, Douglas Taylor via cctalk <cctalk@classiccmp.org> wrote: >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. >> >
