On Mon, Aug 03, 2026 at 10:59:12AM -0700, Len Shustek wrote: > At Sat, 1 Aug 2026 20:42:23 -0400, David Gesswein <[email protected]> wrote: > > The reader is a bunch of instrument amps that amplify to levels usable by > > Saleae logic 16 pro which has analog digitization mode and way too many > > times repurposed code to decode it. Doesn't look like I have put it online > > probably because the code is embarrassing but ok with giving it away if > > someone has use for it. > > Here's an alternative to consider: Years ago I wrote a program to decode > waveforms digitized from cruddy old mag tapes in various formats, > including 7-track NRZI, 9-track NRZI, PE, and GCR, and 6-track Whirlwind. > https://github.com/LenShustek/readtape > We've read hundreds of tapes, mostly digitized using a Saleae analyzer. > I never wrote a DECtape decoder, but it would be doable. >
I looked at your code at the start. DECtapes aren't anything like 9 track. They are closest to wirlwind so thought about trying to modify that. Ended up adding the analog to digital decoding to my existing digital decode code vs learning a new code base and modifying it. Was harder getting good bits from the analog data than I thought so may not have been the best choice. The code works pretty well now.
