2 Nov
2025
2 Nov
'25
5:25 p.m.
On Sun, Nov 02, 2025 at 02:06:00PM -0500, Paul Koning wrote:
Is Dave's setup a DECtape drive, with 10 tracks on 3/4 inch width?
Drive is actually LINCtape with weird tape path so DECtapes need to be
respooled on another drive to LINCtape orientation.
Looks like this
https://www.ricomputermuseum.org/collections-gallery/interesting_computer_i…
All tracks are available from the head separately except mark track which
is why I picked it.
Current project is LINCtapes. Need to do some code changes to merge in my
DECtape decoder. Bottom links are recent stuff.
https://www.pdp8online.com/images/index.shtml
Analog capture would be a great option for old tapes.
It's likely there will be tapes that don't read cleanly with standard controllers,
but could be recovered with analog capture and good DSP.
So far not much DSP. Deskew and handling mark track errors seems to get most
blocks.
And yes, it would of course deal with odd formats.
Then again, reading PDP-10 tapes on a PDP-11 is easy; RT-11 has a standard utility that
does this, using the controller's standard "read all" command. I'm not
sure how a PDP-8 would cope, given that the standard PDP-8 blocksize is quite different.
One thing an analog capture system would do that DECtapes would have trouble with is
reading LINCtape, because RALL assumes (I believe) standard DECtape mark track codes and
LINCtape has an entirely different mark track.
Had been using my PDP-8 TD8E to read DEC & LINC tapes then BeagleBone instead
of TD8E. Some of the LINCtapes I could read with the new setup I couldn't read
with the old.
There was PIP10 to read PDP-10 tapes so I think all PDP-8 controllers could
deal with the different block size. LINCtapes have inverted timing track and
different mark track codes. TD8E could read them some with inverter on timing
track signal and special code.