Connecting a terminal to ODT
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Paulo Rebordão
Aug 21, 2025, 12:44:19 PMAug 21
to [PiDP-11]
I'm trying to connect a terminal session to ODT on a M8190 CPU board.
I know that the speed is configured via dip switches, but what about the rest ?
Should I assume 8 bits, 1 stop, no parity, no flow control ?
Thanks
John Hudak
Aug 21, 2025, 4:03:50 PMAug 21
to Paulo Rebordão, [PiDP-11]
IIRC, parity bit 7 for all input characters is ignored by console ODT. If the characters are echoed,the state of the parity bit is copied to the output buffer (as presumably sent to the terminal). Also, IIRC, 8 bits, 1 stop, no parity and no flow control.
On boot of the KDJ-11, it runs some tests and outputs the result to the SLU. you could try various combinations of bits/stop/parity. I am almost positive the on board diagnostics dont support flow control....whew, this has been a long while since I did this.
Maybe the UG has some answers?
HTH
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John Hudak
Aug 21, 2025, 4:22:30 PMAug 21
to Paulo Rebordão, [PiDP-11]
Forgot to add, also check the MicroNotes for the 11/23 and 11/73 systems. Both the MicroNotes and UG are on bit savers.
Good luck
Johnny Billquist
Aug 21, 2025, 7:45:35 PMAug 21
to pid...@googlegroups.com
I think it's slightly wrong to say it reflects parity. Basically, it's
just 8-bit clean, no parity.
By the time of the KDJ11 boards, DEC was generally pushing for DEC MCS
everywhere, which is almost identical to Latin-1. And that is an 8-bit
character set. All output by the boot monitor is basically 8N1. I don't
think any PDP-11 boot monitor ever supported different languages (but I
could be wrong), but VAXen certainly did, using MCS. And once any DEC OS
booted, it assumed 8N1 as well, unless you told it otherwise.
But this basically means that yes, any input is just reflected back the
way you typed it. You might be right in that it would strip input to
7-bit before parsing. I would have to test, as I don't remember for sure.
But this is the main reason I did the 8-bit cleanup of the console
driver for 2.11BSD way back. I ran an 11/84 and I constantly had to
change the terminal setup if I booted 2.11BSD or RSX, as RSX assumed I
ran with MCS, and 2.11BSD was always doing 7E1 or something like that,
so after the boot monitor, things were always messed up on my terminal.
And 2.11BSD didn't even have the ability to run 8-bit clean on the
console back then.
Johnny
On 2025-08-21 22:03, John Hudak wrote:
> IIRC, parity bit 7 for all input characters is ignored by console ODT.
> If the characters are echoed,the state of the parity bit is copied to
> the output buffer (as presumably sent to the terminal). Also, IIRC, 8
> bits, 1 stop, no parity and no flow control.
> On boot of the KDJ-11, it runs some tests and outputs the result to the
> SLU. you could try various combinations of bits/stop/parity. I am
> almost positive the on board diagnostics dont support flow
> control....whew, this has been a long while since I did this.
> Maybe the UG has some answers?
> HTH
>
>
> On Thu, Aug 21, 2025 at 12:44 PM Paulo Rebordão <pjreb...@gmail.com
> <mailto:pjreb...@gmail.com>> wrote:
>
> I'm trying to connect a terminal session to ODT on a M8190 CPU board.
> I know that the speed is configured via dip switches, but what about
> the rest ?
>
> Should I assume 8 bits, 1 stop, no parity, no flow control ?
>
> Thanks
>
> --
> You received this message because you are subscribed to the Google
> Groups "[PiDP-11]" group.
> To unsubscribe from this group and stop receiving emails from it,
> send an email to pidp-11+u...@googlegroups.com
> <mailto:pidp-11+u...@googlegroups.com>.
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> <https://groups.google.com/d/msgid/pidp-11/
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> utm_medium=email&utm_source=footer>.
--
Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: b...@softjar.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol
just 8-bit clean, no parity.
By the time of the KDJ11 boards, DEC was generally pushing for DEC MCS
everywhere, which is almost identical to Latin-1. And that is an 8-bit
character set. All output by the boot monitor is basically 8N1. I don't
think any PDP-11 boot monitor ever supported different languages (but I
could be wrong), but VAXen certainly did, using MCS. And once any DEC OS
booted, it assumed 8N1 as well, unless you told it otherwise.
But this basically means that yes, any input is just reflected back the
way you typed it. You might be right in that it would strip input to
7-bit before parsing. I would have to test, as I don't remember for sure.
But this is the main reason I did the 8-bit cleanup of the console
driver for 2.11BSD way back. I ran an 11/84 and I constantly had to
change the terminal setup if I booted 2.11BSD or RSX, as RSX assumed I
ran with MCS, and 2.11BSD was always doing 7E1 or something like that,
so after the boot monitor, things were always messed up on my terminal.
And 2.11BSD didn't even have the ability to run 8-bit clean on the
console back then.
Johnny
On 2025-08-21 22:03, John Hudak wrote:
> IIRC, parity bit 7 for all input characters is ignored by console ODT.
> If the characters are echoed,the state of the parity bit is copied to
> the output buffer (as presumably sent to the terminal). Also, IIRC, 8
> bits, 1 stop, no parity and no flow control.
> On boot of the KDJ-11, it runs some tests and outputs the result to the
> SLU. you could try various combinations of bits/stop/parity. I am
> almost positive the on board diagnostics dont support flow
> control....whew, this has been a long while since I did this.
> Maybe the UG has some answers?
> HTH
>
>
> On Thu, Aug 21, 2025 at 12:44 PM Paulo Rebordão <pjreb...@gmail.com
> <mailto:pjreb...@gmail.com>> wrote:
>
> I'm trying to connect a terminal session to ODT on a M8190 CPU board.
> I know that the speed is configured via dip switches, but what about
> the rest ?
>
> Should I assume 8 bits, 1 stop, no parity, no flow control ?
>
> Thanks
>
> --
> You received this message because you are subscribed to the Google
> Groups "[PiDP-11]" group.
> To unsubscribe from this group and stop receiving emails from it,
> send an email to pidp-11+u...@googlegroups.com
> To view this discussion visit https://groups.google.com/d/msgid/
> pidp-11/b117f744-0dc4-423c-8569-b8f73ac2f9e5n%40googlegroups.com
> <https://groups.google.com/d/msgid/pidp-11/b117f744-0dc4-423c-8569-
> pidp-11/b117f744-0dc4-423c-8569-b8f73ac2f9e5n%40googlegroups.com
> b8f73ac2f9e5n%40googlegroups.com?utm_medium=email&utm_source=footer>.
>
> --
> You received this message because you are subscribed to the Google
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> To view this discussion visit https://groups.google.com/d/msgid/pidp-11/
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> <https://groups.google.com/d/msgid/pidp-11/
> CAE%3DviVpW_PuDfmKEMbcqm5moyCMsyRoo8XhzcRukOJVg5UjqPQ%40mail.gmail.com?
> utm_medium=email&utm_source=footer>.
--
Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: b...@softjar.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol
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