[Simh] PDP-10 DECtapes

[Bob Supnik]

Johnny Billquist wrote:

I don't know if I'd call the TD8E arcane. Like I said before, it is the
most stupid controller ever invented.
I had to write code last year to extract 18b images from a PDP-15 using
the TD8E. Reading through the documentation, and reading through the
TD8E driver as well as PIP10 was enough for me to understand how it
worked, so you should be able to do the same.
Basically, the TD8E gives you almost nothing at all. You need to do just
about all the fiddling yourself.
It is horribly stupid and primitive.

I agree; and the TD8E simulator reads and writes OS/8 format DECtapes just fine.

The problem is that it doesn't work with Mark Bramhall's handcrafted DECtape drivers in PIP10. Tracing what the TD8E simulator is doing, versus what Mark's driver is expecting, is the complication.

On the TC08, all the cruft is hidden, and the simulator operates on a word-by-word basis. On the TD8E, all the cruft is exposed, and the simulator operates on a line-by-line basis. It also has to simulate the the mark track codes on a bit-by-bit basis. I suspect that the mark track simulation isn't quite right with non-standard block sizes.

/Bob