30 Nov
2022
30 Nov
'22
6:46 p.m.
On 11/30/22 10:41, Chuck Guzis via cctalk wrote:
On 11/30/22 01:30, Christian Corti via cctalk wrote:
NRZI is fairly simple, there is logic in the drive that
produces a strobe approximately at the center of the
character. For writing, there is a write gate that enables
the erase head, and a data strobe.
For PE, you just get the transitions from the read amps.
Some drives have squelch that turns off the read signal
until the amplitude exceeds a threshold.
So, unformatted Pertec is as close to the signals on the
tape as you can get in a digital format.
Jon
On Sun, 27 Nov 2022, Chuck Guzis wrote:
It's not impossible, but was there a universal standard for the
unformatted side of the affair? There are small differences between
the formatted side between vendors as-is.
I use an MCU as a formatter.controller on my HP7970 drive. But that's
just an NRZI model, so it's pretty easy.
--Chuck
If anyone cares, I've been working on a
Pertec tape controller design.
The initial version worked remarkably well with only a few bodge wires.
I'm assembling the respin of the design and do not anticipate any issues.
I could really use some "Unformatted to Pertec" tape controllers. I have
a bunch of ½" drives but no separate formatter. So ATM they are quite
useless.