On Sat, May 2, 2009 at 5:36 PM, Alexandre Souza <alexandre-listas at e-secure.com.br> wrote: What a shame. I went looking for that datasheet out of curiosity, and it looks like a really fun little chip, easy to use, etc. It would have been great to stuff on a C-64 or a PET as a trivial D-A. We built equivalent sorts of things like that from discrete components on the PET for music that was higher quality than just frobbing the CB2 clock (User Port sound). Pump out bits, let the hardware sum up the voltage, amplify and listen. There was a PC version called the "Disney Sound Source" from that brief era between silent PCs and the first "multimedia" games. I have one from testing games for Activision in the early 1990s. I've wanted a simple solution like the ZN428E for driving an analog meter from an 8-bit port. I rigged up a simple ladder D-A a couple of years back, but I didn't do anything about cumulative inaccuracy when, say, ramping from 0x7F to 0x80 (the needle would dip). Using an internal ladder (or R2R) network would be much more accurate than my lucky-dip and hand-sorting technique. It's a shame that it's an orphan now. -ethan

Philip Pemberton wrote: I did the ladder DAC route too, way back in the early days of adding trivial sound to PCs - then went with a ZN428E solution. IIRC various pieces of audio-playback software* supported them, along with a few games (I think Wolfenstein 3D was possibly one of the latter) * I think I found the ASCII-based schematic that I used bundled with one of them, actually. I can't remember if I still have the ZN428E board - I was terrible for building projects, using them for a while, then growing bored of them and salvaging all the useful components for other things :-) cheers Jules