I wouldn't want to violate my NDA!
On July 11, 2023 12:42:57 p.m. EDT, Douglas Taylor via cctalk <cctalk@classiccmp.org> wrote: >Funny you mention that, I've got a Data Translation DT2766 and it is identical >to the AAV11-C. I mean identical! In the day DT must have sold them based on >2 selling points: (1) Cheaper than DEC and (2) Exact drop in replacement for >the DEC AAV11-C. > >Doug > >On 7/11/2023 12:33 PM, Nigel Johnson via cctalk wrote: >> 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. > >
