[Simh] PDP-10 DECtapes

[Johnny Billquist]

On 2013-03-28 16:43, Bob Supnik wrote:
> Johnny Billquist wrote:
>
>> 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.

Even that is actually quite an accomplishment, if you ask me.

> 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.

I bet.

> 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.

Yes. The TC08 is a sane thing in comparison. Not to mention that the 
emulation can be done at a reasonable level.
I would also suspect the mark track simulation. That is where most of 
the magic happens.

Sorry that I can't offer more help. I'm way too busy with other things 
right now to add yet another project. All I can do is to make some 
comments that I hope might atleast offer encouragement. (I did send some 
patches to the VAX8600 code in simh last week, and I'm trying to fix 
NetBSD working on that emulation, as well as all my pdp11-related work 
(not all simh related though)...)

	Johnny

-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at softjar.se             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol