[HECnet] RT-11 filesystems, was Re: DECnet-RT?

On Tuesday, March 31, 2020 at 2:45 PM, Clem Cole wrote: I've forgotten to be honest -- IIRC, no formatting was needed like a traditional tape drive. But it is possible we may have had a program to do the formatting and I've just forgotten it. I do remember that it was a very simple, saturation scheme. We had a scope on the read electronics of the TA11 and decoded it all. NRZ style, 8-bit bytes, no parity, fixed blocks with a prefix and suffix - serial encoding (unlike a 7/9-track) - which is why the capacity is so low. Again, I've forgotten, we had the prints for the TA11 controller and its very possible the format info was in there -- I really don't remember. It was just a stream of bits down the tape, not serpentine like a QIC tape (which has a head that switches 'tracks' and writes a long stream turns the tape around and then switches to the next head and writes it backward. I've forgotten if you got one to two passes on TA11. Traditional Phillips tape could be flipped over (side 1 and 2). I don't remember if TA11's worked that way.