[Simh] pdp11 - console input with high bit set

[Mark Pizzolato - Info Comm]

On Friday, July 24, 2020 at 5:42 PM, David Gesswein wrote:
> On Sat, Jul 25, 2020 at 01:22:38AM +0200, Johnny Billquist wrote:
> > >
> > > I thought the high bit setting would be turned off if you used set
> > > tti 7b or 8b but never verified.
> >
> > Which obviously won't help if the software running inside simh then
> > expects MARK parity...
> >
> Correct. That was for software that doesn't want mark parity.
> 
> Probably should had quoted this from the posting.
> 
> > So basically pdp8 is always doing KSR. I assume that I don’t want that
> > for pdp11.
> >
> 
> pdp8_doc.doc 2.4.3 KL8E Terminal Input says it will not force mark parity if
> you specify 7P, 7B, or 8B.
> 
> The rest of the context.
> 
> I am running it in the windows console.
> 
> I can see that setting TTU_KSR on the mode flags passed to sim_tt_impcvt
> will do the job. The pdp-8 console hard code this bit on
> 
> else uptr->buf = sim_tt_inpcvt (c, TT_GET_MODE (uptr->flags) | TTUF_KSR);
> 
> the is also a KSR mode switch
> 
> MTAB tti_mod[] = {
>     { TT_MODE, TT_MODE_KSR, "KSR", "KSR", &tty_set_mode },
> 
> But this only forces UC (sim_console.h)
> 
> #define  TT_MODE_KSR    (TT_MODE_UC)

Absolutely true AND the TTUF_KSR flag passed to sim_tt_inpcvt is only interpreted 
when in upper case mode.  The latest code has a KSR mode for TTI which is upper 
case with Mark parity.  Additionally, there are options to provide SPACE, MARK, EVEN 
and ODD parity for any of the 7 bit character input modes.

Your above change isn't needed anymore, but also won't hurt anything (unless somehow 
you want Upper Case only and a parity option other than MARK).  It is best left off.

- Mark