[Simh] PDP10: KS10 console lights?

[Bob Eager]

On Fri, 7 Sep 2018 23:17:56 -0400
Clem Cole <clemc at ccc.com> wrote:

> On Fri, Sep 7, 2018 at 1:52 AM Lars Brinkhoff <lars at nocrew.org> wrote:
> 
> > Timothe Litt wrote:
> > > > I have checked the KS10 instruction set.  It doesn't have a
> > > > DATAO PI, instruction.  However that particular opcode isn't in
> > > > used, so it's just a UUO.  This is also the case for ITS
> > > > microcode.  Before I start working on anything, I'd like to ask
> > > > if it would be OK to repurpose this opcode for its traditional
> > > > use?
> > >
> > > Neither the KL nor the KS use DATAO PI,. I don't have a problem
> > > with implementing it for the KS. It would need to act like any IO
> > > instruction - MUUO in user mode, functional in Exec and with
> > > User-In-Out.
> >
> > Of course.
> >
> > The next problem is, how to access USB from SIMH?  I have something
> > that works in Linux.  I checked SIMH to see if there's a built in
> > USB API that works across operating system, but I didn't see any.
> 
> I believe that device is using an FTDI chip set, which
> Linux/MacOS/Winders etc will see as a dynamic serial port that
> appears at attach time.   You use open it and used traditional read
> and write.  FWIW:  If you grab the sources to the Arduino IDE and
> look at the interface code in there - it knows rules on how the port
> names will be generated in the different OSses which will be thr one
> tricky part, since the rules.

The problem can also be (in at least FreeBSD) that the order of
enumeration of the USB ports can change depending on what else is
plugged in. This means that there is no consistent 'serial' port name.

I solved this by setting up a symbolic link to the correct port and
opening that in the program.

The symlink is generated (on FreeBSD) by an entry in devd.conf, which
detects the correct USB port by serial number, then matches that with
the 'serial' port name using the sysctl entries. Sounds complicated but
it's all scripted. One would hope that other systems can do something
similar.