Understood.
Again I agree. But I am curious, why has SIMH dropped
what little support it did have for the Application Keypad on the VT100?
Also, why has some eager beaver not stepped up to the plate and
developed
an option for SIMH to provide that support for RT-11 fellows like
myself?
We're talking about very different things. I will try to explain
what I mean.
SIMH doesn't "support" specific keys or specific terminal emulations
at all, because that's outside its scope. It's very much like saying
a PDP-11/23 (for example) "supports" a VT100, or a PDP-11/23 supports
PF keys, or some other terminal function. It doesn't...it has serial
ports, and the OS (as you know) squirts bytes in and out of those
serial ports, and what the terminal or the OS (or the app software for
that matter) has nothing to do with the fact that the computer is, in
this example, a PDP-11/23.
A PDP-11/23 "has support for" a VT100's PF keys if a VT100 terminal
(or a clone) is plugged into it. In exactly this same way, SIMH "has
support for" PF keys if a VT100 terminal is "plugged into" it.
Say I start a terminal program like "gnome-terminal", which is a
common terminal program on Linux and Solaris machines. In that
terminal window, I get a shell prompt. I start SIMH, which creates a
virtual PDP-11 whose default console port (777566) is logically
"connected to" a terminal...not a hardware VT100, but the instance of
the "gnome-terminal" program. It speaks ANSI codes and mostly
implements a VT100, so <esc>[2J will clear the screen, <esc>[H homes
the cursor, etc. All of these functions are completely outside the
scope of SIMH. If, say, I boot RSTS/E on that virtual PDP-11, do SET
TERM/DEV=VT100", and I fire up EDT, then tell EDT to "SET MODE
CHANGE", the first thing that happens (more or less) is that EDT sends
<esc>[2J to clear the screen. SIMH never sees this...or, more
correctly, it sees those four bytes written to 777566, and squirts
them through the emulated serial port untouched. At that point, they
are no longer the responsibility of SIMH. It's up to the "terminal"
that is "connected" to this virtual PDP-11 to understand what those
bytes mean and what to do with them.
If I had started SIMH under a terminal program that only understands
the control codes of, say, an LSI ADM-3A, that EDT session would look
like gibberish.
In this way, I can start SIMH under any sort of terminal (iTerm
under OS X has wonderful full-VT-keypad emulation) and have things
work the way I want them to, for any desired configuration. I can
even start it under a pseudo-terminal that has no display, but watches
for patterns sent from SIMH and sends responses accordingly, as if
they'd been typed by a human. (an "expect" script, for anyone into
such things)
What you are (or seem to be) talking about is starting a PDP-11
emulator that somehow opens its own window, thus creating a virtual
terminal of sorts, and that terminal is responsible for interpreting
the control codes, and handling key events and translating them to the
appropriate bytes to send to the emulated PDP-11's emulated serial port.
This is certainly a reasonable setup, but it locks you into one
specific configuration that may or may not be what you want. A car
and an oven may be a handy combination sometimes, but they perform
different tasks, and only having a car with an oven, or only having an
oven in the car, might sometimes be very limiting and inconvenient.
SIMH, to my knowledge, has never done this on any of its native
platforms. I've not spoken with Bob Supnik about this, but if it did
in fact do this on its Windows port, and it doesn't any longer, it's
likely because Bob realized the above and removed that functionality.
I certainly would have. After all, if every PDP-11/23 came with a
VT100 permanently and undetachably connected to its console port, what
would a person do if they wanted an LA36 on the console?
While I agree with everything that you have written, I still STRONGLY
suggest that SIMH have an optional set of terminal interfaces which are
able to emulate the most popular terminals which DEC supported for
the PDP-11. While I agree that supporting all of the video terminals
at least supporting the VT100 would provide 95% of the functions
needed to run SIMH with a PDP-11, in particular for RT-11 when
SL: is used or in general for RSTS/E when ARROW keys are used.
I also agree that the reason that Bob removed the VT100 Application
Keypad functions was likely for the reasons you suggest.
So while having a VT100 permanently connected to every PDP-11
running under SIMH is not the solution that Bob Subnik adopted,
having that as an option would seem to have been helpful for those
users who need a VT100 display interface.
On the other hand, while Ersatz-11 does allow major flexibility on
the keyboard side, on the display side of the fence, it is a VT100 by
default all of the time. If someone wanted an LA36 on the console,
then it is possible to change some of the display parameters. But
since the output is still to a video display, then VT100 type of
character handling seems the most appropriate in any case.
In short, if you are using any standard PC these days, a hard copy
display is just not available in any case as an option as far as I am
aware. However, with Ersatz-11 it would be possible to have a
serial port with a cable attached to an LA36 on the console in
which case the operator could tell the operating system that an
LA36 was being used.
In this case, I agree with the default selection for SIMH, I just
disagree that there is no VT100 support as an option.
Jeome Fine