> On Jul 24, 2020, at 2:28 PM, David Gesswein <[email protected]> wrote:
>
> On Fri, Jul 24, 2020 at 06:12:17PM +0000, Paul Moore wrote:
>> Not helped by not knowing what KSR really means.
>>
>
> Keyboard send receive. A model 33 teletype without paper tape.
> ASR was the model with paper tape, Automatic send receive.
>
> DEC used teletype's that generated mark parity. From the manuals keyboards
> were
> available to generate other parity. A reasonable amount of old code for
> PDP-8's assumed mark parity. Later code ignores the upper bit.
>
> I thought the high bit setting would be turned off if you used set tti 7b or
> 8b but never verified.
7b, yes. But that only helps with software that sets the top bit on output, as
some old Unices do. It doesn't help with the problem Paul M raised, which is
software that insists on mark parity input.
The right answer would be a tweak to the console emulation in SIMH pdp11. I
wonder if this was done for PDP8 and not PDP11 because it was known to be
needed on the one but people hadn't run into it for the other.
paul
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