[cctalk] Re: New TU56 Tape Images Available for simH use

[Paul Koning via cctalk]

> On Aug 1, 2026, at 8:42 PM, David Gesswein via cctalk <cctalk@classiccmp.org> 
> wrote:
> 
> ...
>> Did he use read-all mode to read the raw tape structure?  Or is this 
>> something
>> lower level still, without using a TC11 controller?
>> 
> I have used my TD8E PDP-8 controller to read tapes.  I tried 
> inverting the timing track for reading LINCtapes with the PDP8 but it was hit 
> or miss so I created the analog digitizer with software decode.
> It hooks directly to the head cable.

As I recall, LINCtape has 4 bit mark track codes rather than 6 bit.  I had to 
sort this out at one time to write a Python program to recover data from 
LINCtape captures.  Don't remember where I found the documentation...  I assume 
those were captures you did.

Hard to imagine how even an "agnostic" DECtape controller can cope with tapes 
that have 4 bit mark track codewords...

        paul