Re: [Simh] Problem using a real VT terminal with simh

[khandy21yo]

Have you configured the centos serial port to anything? It may be the problem.


Sent from my Galaxy Tab® A
 Original message From: Peter Allan  
Date: 12/5/17  10:56 AM  (GMT-07:00) To: simh@trailing-edge.com Subject: [Simh] 
Problem using a real VT terminal with simh 
I am trying to get a real VT420 terminal working with a simulated micro VAX 
3900. However, I am having problems getting text displayed on the screen of the 
VT420.
The host for simh is a standard PC running CentOS 6.9.
I am connecting the VT420 to the PC using the 25-pin RS232 connector at the 
back of the VT420, going via a 25-pin to 9-pin adaptor, to the 9-pin RS232 
connector on the PC. I am convinced that the physical connection is correct 
since I can start an agetty process at boot time and log into CentOS from the 
VT420. Everything works and displays as I would expect. 
For what follows, I have removed the starting of the agetty process so that 
nothing is controlling the /dev/ttyS0 device before I start simh.
The simulated microVAX 3900 is running VMS 7.3 from an RA92 disk. This 
configuration has been running successfully for a long time and I am only now 
trying to add the connection of a physical terminal.
In the vax.ini file, I have added the lines
SET DZ LINES=4ATTACH DZ LINE=0,CONNECT=SER0
Once the microVAX has booted, if I hit Enter on the VT420, then I can see that 
a login process starts on the simulated microVAX, but all I see on the screen 
of the VT420 is a few garbage characters. Despite that, when I type a username 
and a password, I do get logged into the simulated microVAX. Any commands that 
I type on the keyboard of the VT420 appears on the screen of the VT420 (except 
the password, of course), but anything that the microVAX is sending to the 
VT420 appears as garbage. There are recognisable characters, but if I TYPE a 
file, even a small one, what appears seems to be every 7th character from the 
file starting with the first character. The output of commands such as DIR 
appear to have the same problem.
Furthermore, when I log into the microVAX, the VT420 goes through a reset, as 
though I had turned it off and on. I think this is because the login sequence 
does a SET TERMINAL/INQUIRE since if I type that command, exactly the same 
thing happens. This seems particularly odd since I have used that command many 
times with a real computer (although admittedly not with this particular 
terminal) and I have never seen this happen before.
The VT420's RS232 port is set to a speed of 9600, with 8 bits and no parity and 
the TTA0: device on the microVAX also gets set to this combination.
Hopefully I am just doing something wrong, but I can't see what that might be. 
Can anyone help with this please?
Peter Allan

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Re: [Simh] Problem using a real VT terminal with simh

[khandy21yo]

I'd suspect  a problem with the 8th bit being handled funny , maybe mark parity 
Are the characters in the right pattern to be vms prompts, and are they always 
the same? 
If you can log  into linux fine on that terminal, telnet from there Into the 
emulator and see what happens. You can telnet in via cup or set the dh lines to 
be telnet ports.



Sent from my Galaxy Tab® A
 Original message From: Peter Allan <petermal...@gmail.com> 
Date: 12/5/17  1:38 PM  (GMT-07:00) To: Mark Pizzolato <m...@infocomm.com>, 
simh@trailing-edge.com Subject: Re: [Simh] Problem using a real VT terminal 
with simh 
Thanks to everyone for their quick responses.
To my surprise, Xon/Xoff was turned off on the VAX, specifically, SHOW TERM 
TTA0 showed No HostSync. However SET TERM/PERM/HOSTSYNC TTA0 made no difference.
I have tried setting the line speed to 2400, but that only slows down the 
output. It still contains the same characters, to the extent that I can tell. 
I will continue to experiment and I will try using a different computer so that 
the serial port hardware is (presumably) different. If I can't solve it, I will 
indeed create an issue on github as Mark suggests.
Cheers
Peter Allan

On 5 December 2017 at 19:30, Mark Pizzolato <m...@infocomm.com> wrote:
On Tuesday, December 5, 2017 at 10:08 AM, Paul Koning wrote:

> Do you have flow control (Xon/Xoff) enabled both on the terminal and on the

> VAX?

>

> You might try a slower speed to see if that makes a difference.  It shouldn't,

> but it might give more information.

>

> Is autobaud enabled on the line?  You might turn that off and set the speed

> and related parameters explicitly.



These are all great suggestions.  Autobaud should definitely be turned off on

the VMS side, but I don't think that is the problem since he's able to login

and the commands he types produce output, which merely is garbled.



A slower speed, which is explicitly stated on the ATTACH command might

help.

     sim> ATTACH DZ LINE=0,CONNECT=SER0;2400-8N1



I think that what you're seeing is output from the simulator overrunning

the host OS provided interface to the serial port.  This came up a while back.

The simulator serial port interface delivers data to the host OS driver one

character at a time as it is emitted by the simulator.  The simulator is

notified of I/O completion when the host OS said the IO was complete.

On some operating systems, this completion notification merely indicated

that the data had made it to a kernel buffer and not actually out through

the hardware.  This early completion indication then was passed back

through the simulator and more data was then emitted.  Ultimately it seemed

that there was not a reliable way to know that the data has actually, not only

made it to the hardware, but actually been transmitted.  Some relatively

common serial ports have an output buffer in the hardware that will take

a number of characters to be transmitted as quickly as the host puts them

into the hardware, and then deliver it outbound after the fact.  In any case

due to the problem of not getting a precise indication from the OS driver of

when the data actually made it out the serial port, an alternative approach

was taken.  This approach attempts to time the delivery of character I/O

data to the OS driver by explicitly scheduling the I/O completion time based

on the port specified speed.  This approach presumes that the OS actually

starts to send some of the data to the serial port when it is presented and

doesn't hold off until some buffer full condition is achieved.



If the above ATTACH suggestion doesn't work for you, please create an issue

at https://github.com/simh/simh/issues and we can try to dig into this further.



> > On Dec 5, 2017, at 12:56 PM, Peter Allan <petermal...@gmail.com> wrote:

> >

> > I am trying to get a real VT420 terminal working with a simulated micro VAX

> 3900. However, I am having problems getting text displayed on the screen of

> the VT420.

> > ...

> > Once the microVAX has booted, if I hit Enter on the VT420, then I can see

> that a login process starts on the simulated microVAX, but all I see on the

> screen of the VT420 is a few garbage characters. Despite that, when I type a

> username and a password, I do get logged into the simulated microVAX. Any

> commands that I type on the keyboard of the VT420 appears on the screen of

> the VT420 (except the password, of course), but anything that the microVAX is

> sending to the VT420 appears as garbage. There are recognisable characters,

> but if I TYPE a file, even a small one, what appears seems to be every 7th

> character from the file starting with the first character. The output of

> commands such as DIR appear to have the same problem. ...

> ___

Re: [Simh] Problem using a real VT terminal with simh

[Mark Pizzolato]

Hi Peter,

Even if you do solve the problem by some different combination of things, the 
problem you’re seeing is real and possibly generic, so understanding the 
differences between when it failed and when it worked may lead to a different 
approach which works more universally.  So, please create an issue either way.

Meanwhile, you might try a different simulated device for this activity.

Instead of:
  sim> ATTACH DZ Line=0,CONNECT=SER0;2400-8N1
please try:
  sim> SET CONSOLE SERIAL=SER0;2400-8N1


-  Mark

From: Peter Allan [mailto:petermal...@gmail.com]
Sent: Tuesday, December 5, 2017 12:39 PM
To: Mark Pizzolato <m...@infocomm.com>; simh@trailing-edge.com
Subject: Re: [Simh] Problem using a real VT terminal with simh

Thanks to everyone for their quick responses.

To my surprise, Xon/Xoff was turned off on the VAX, specifically, SHOW TERM 
TTA0 showed No HostSync. However SET TERM/PERM/HOSTSYNC TTA0 made no difference.

I have tried setting the line speed to 2400, but that only slows down the 
output. It still contains the same characters, to the extent that I can tell.

I will continue to experiment and I will try using a different computer so that 
the serial port hardware is (presumably) different. If I can't solve it, I will 
indeed create an issue on github as Mark suggests.

Cheers

Peter Allan


On 5 December 2017 at 19:30, Mark Pizzolato 
<m...@infocomm.com<mailto:m...@infocomm.com>> wrote:
On Tuesday, December 5, 2017 at 10:08 AM, Paul Koning wrote:
> Do you have flow control (Xon/Xoff) enabled both on the terminal and on the
> VAX?
>
> You might try a slower speed to see if that makes a difference.  It shouldn't,
> but it might give more information.
>
> Is autobaud enabled on the line?  You might turn that off and set the speed
> and related parameters explicitly.

These are all great suggestions.  Autobaud should definitely be turned off on
the VMS side, but I don't think that is the problem since he's able to login
and the commands he types produce output, which merely is garbled.

A slower speed, which is explicitly stated on the ATTACH command might
help.
 sim> ATTACH DZ LINE=0,CONNECT=SER0;2400-8N1

I think that what you're seeing is output from the simulator overrunning
the host OS provided interface to the serial port.  This came up a while back.
The simulator serial port interface delivers data to the host OS driver one
character at a time as it is emitted by the simulator.  The simulator is
notified of I/O completion when the host OS said the IO was complete.
On some operating systems, this completion notification merely indicated
that the data had made it to a kernel buffer and not actually out through
the hardware.  This early completion indication then was passed back
through the simulator and more data was then emitted.  Ultimately it seemed
that there was not a reliable way to know that the data has actually, not only
made it to the hardware, but actually been transmitted.  Some relatively
common serial ports have an output buffer in the hardware that will take
a number of characters to be transmitted as quickly as the host puts them
into the hardware, and then deliver it outbound after the fact.  In any case
due to the problem of not getting a precise indication from the OS driver of
when the data actually made it out the serial port, an alternative approach
was taken.  This approach attempts to time the delivery of character I/O
data to the OS driver by explicitly scheduling the I/O completion time based
on the port specified speed.  This approach presumes that the OS actually
starts to send some of the data to the serial port when it is presented and
doesn't hold off until some buffer full condition is achieved.

If the above ATTACH suggestion doesn't work for you, please create an issue
at https://github.com/simh/simh/issues and we can try to dig into this further.

> > On Dec 5, 2017, at 12:56 PM, Peter Allan 
> > <petermal...@gmail.com<mailto:petermal...@gmail.com>> wrote:
> >
> > I am trying to get a real VT420 terminal working with a simulated micro VAX
> 3900. However, I am having problems getting text displayed on the screen of
> the VT420.
> > ...
> > Once the microVAX has booted, if I hit Enter on the VT420, then I can see
> that a login process starts on the simulated microVAX, but all I see on the
> screen of the VT420 is a few garbage characters. Despite that, when I type a
> username and a password, I do get logged into the simulated microVAX. Any
> commands that I type on the keyboard of the VT420 appears on the screen of
> the VT420 (except the password, of course), but anything that the microVAX is
> sending to the VT420 appears as garbage. There are recognisable characters,
> but if I TYPE a file, even a small one, what appears seems to be every 7th
>

Re: [Simh] Problem using a real VT terminal with simh

[Peter Allan]

Thanks to everyone for their quick responses.

To my surprise, Xon/Xoff was turned off on the VAX, specifically, SHOW TERM
TTA0 showed No HostSync. However SET TERM/PERM/HOSTSYNC TTA0 made no
difference.

I have tried setting the line speed to 2400, but that only slows down the
output. It still contains the same characters, to the extent that I can
tell.

I will continue to experiment and I will try using a different computer so
that the serial port hardware is (presumably) different. If I can't solve
it, I will indeed create an issue on github as Mark suggests.

Cheers

Peter Allan


On 5 December 2017 at 19:30, Mark Pizzolato  wrote:

> On Tuesday, December 5, 2017 at 10:08 AM, Paul Koning wrote:
> > Do you have flow control (Xon/Xoff) enabled both on the terminal and on
> the
> > VAX?
> >
> > You might try a slower speed to see if that makes a difference.  It
> shouldn't,
> > but it might give more information.
> >
> > Is autobaud enabled on the line?  You might turn that off and set the
> speed
> > and related parameters explicitly.
>
> These are all great suggestions.  Autobaud should definitely be turned off
> on
> the VMS side, but I don't think that is the problem since he's able to
> login
> and the commands he types produce output, which merely is garbled.
>
> A slower speed, which is explicitly stated on the ATTACH command might
> help.
>  sim> ATTACH DZ LINE=0,CONNECT=SER0;2400-8N1
>
> I think that what you're seeing is output from the simulator overrunning
> the host OS provided interface to the serial port.  This came up a while
> back.
> The simulator serial port interface delivers data to the host OS driver one
> character at a time as it is emitted by the simulator.  The simulator is
> notified of I/O completion when the host OS said the IO was complete.
> On some operating systems, this completion notification merely indicated
> that the data had made it to a kernel buffer and not actually out through
> the hardware.  This early completion indication then was passed back
> through the simulator and more data was then emitted.  Ultimately it seemed
> that there was not a reliable way to know that the data has actually, not
> only
> made it to the hardware, but actually been transmitted.  Some relatively
> common serial ports have an output buffer in the hardware that will take
> a number of characters to be transmitted as quickly as the host puts them
> into the hardware, and then deliver it outbound after the fact.  In any
> case
> due to the problem of not getting a precise indication from the OS driver
> of
> when the data actually made it out the serial port, an alternative approach
> was taken.  This approach attempts to time the delivery of character I/O
> data to the OS driver by explicitly scheduling the I/O completion time
> based
> on the port specified speed.  This approach presumes that the OS actually
> starts to send some of the data to the serial port when it is presented and
> doesn't hold off until some buffer full condition is achieved.
>
> If the above ATTACH suggestion doesn't work for you, please create an issue
> at https://github.com/simh/simh/issues and we can try to dig into this
> further.
>
> > > On Dec 5, 2017, at 12:56 PM, Peter Allan 
> wrote:
> > >
> > > I am trying to get a real VT420 terminal working with a simulated
> micro VAX
> > 3900. However, I am having problems getting text displayed on the screen
> of
> > the VT420.
> > > ...
> > > Once the microVAX has booted, if I hit Enter on the VT420, then I can
> see
> > that a login process starts on the simulated microVAX, but all I see on
> the
> > screen of the VT420 is a few garbage characters. Despite that, when I
> type a
> > username and a password, I do get logged into the simulated microVAX. Any
> > commands that I type on the keyboard of the VT420 appears on the screen
> of
> > the VT420 (except the password, of course), but anything that the
> microVAX is
> > sending to the VT420 appears as garbage. There are recognisable
> characters,
> > but if I TYPE a file, even a small one, what appears seems to be every
> 7th
> > character from the file starting with the first character. The output of
> > commands such as DIR appear to have the same problem. ...
> > ___
> > Simh mailing list
> > Simh@trailing-edge.com
> > http://mailman.trailing-edge.com/mailman/listinfo/simh
>
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Re: [Simh] Problem using a real VT terminal with simh

[Johnny Billquist]

Another thing to check is transmit and receive speed on the terminal so that 
they aren't different. Many people today fail to realize that they can be 
different and that dec terminals have different settings for the two. The 
"best" might be to set receive speed equal to transmit speed, which one 
specific setting for receive speed. 

  Johnny 


Paul Koning  skrev: (5 december 2017 19:07:42 CET)
>Do you have flow control (Xon/Xoff) enabled both on the terminal and on
>the VAX?
>
>You might try a slower speed to see if that makes a difference.  It
>shouldn't, but it might give more information.
>
>Is autobaud enabled on the line?  You might turn that off and set the
>speed and related parameters explicitly.
>
>   paul
>
>> On Dec 5, 2017, at 12:56 PM, Peter Allan 
>wrote:
>> 
>> I am trying to get a real VT420 terminal working with a simulated
>micro VAX 3900. However, I am having problems getting text displayed on
>the screen of the VT420.
>> ...
>> Once the microVAX has booted, if I hit Enter on the VT420, then I can
>see that a login process starts on the simulated microVAX, but all I
>see on the screen of the VT420 is a few garbage characters. Despite
>that, when I type a username and a password, I do get logged into the
>simulated microVAX. Any commands that I type on the keyboard of the
>VT420 appears on the screen of the VT420 (except the password, of
>course), but anything that the microVAX is sending to the VT420 appears
>as garbage. There are recognisable characters, but if I TYPE a file,
>even a small one, what appears seems to be every 7th character from the
>file starting with the first character. The output of commands such as
>DIR appear to have the same problem. ...
>___
>Simh mailing list
>Simh@trailing-edge.com
>http://mailman.trailing-edge.com/mailman/listinfo/simh

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Re: [Simh] Problem using a real VT terminal with simh

[Mark Pizzolato]

On Tuesday, December 5, 2017 at 10:08 AM, Paul Koning wrote:
> Do you have flow control (Xon/Xoff) enabled both on the terminal and on the
> VAX?
> 
> You might try a slower speed to see if that makes a difference.  It shouldn't,
> but it might give more information.
> 
> Is autobaud enabled on the line?  You might turn that off and set the speed
> and related parameters explicitly.

These are all great suggestions.  Autobaud should definitely be turned off on 
the VMS side, but I don't think that is the problem since he's able to login
and the commands he types produce output, which merely is garbled.

A slower speed, which is explicitly stated on the ATTACH command might
help.
 sim> ATTACH DZ LINE=0,CONNECT=SER0;2400-8N1

I think that what you're seeing is output from the simulator overrunning 
the host OS provided interface to the serial port.  This came up a while back.
The simulator serial port interface delivers data to the host OS driver one
character at a time as it is emitted by the simulator.  The simulator is 
notified of I/O completion when the host OS said the IO was complete.
On some operating systems, this completion notification merely indicated
that the data had made it to a kernel buffer and not actually out through
the hardware.  This early completion indication then was passed back 
through the simulator and more data was then emitted.  Ultimately it seemed
that there was not a reliable way to know that the data has actually, not only
made it to the hardware, but actually been transmitted.  Some relatively 
common serial ports have an output buffer in the hardware that will take 
a number of characters to be transmitted as quickly as the host puts them 
into the hardware, and then deliver it outbound after the fact.  In any case
due to the problem of not getting a precise indication from the OS driver of
when the data actually made it out the serial port, an alternative approach
was taken.  This approach attempts to time the delivery of character I/O 
data to the OS driver by explicitly scheduling the I/O completion time based
on the port specified speed.  This approach presumes that the OS actually
starts to send some of the data to the serial port when it is presented and 
doesn't hold off until some buffer full condition is achieved.

If the above ATTACH suggestion doesn't work for you, please create an issue
at https://github.com/simh/simh/issues and we can try to dig into this further.

> > On Dec 5, 2017, at 12:56 PM, Peter Allan  wrote:
> >
> > I am trying to get a real VT420 terminal working with a simulated micro VAX
> 3900. However, I am having problems getting text displayed on the screen of
> the VT420.
> > ...
> > Once the microVAX has booted, if I hit Enter on the VT420, then I can see
> that a login process starts on the simulated microVAX, but all I see on the
> screen of the VT420 is a few garbage characters. Despite that, when I type a
> username and a password, I do get logged into the simulated microVAX. Any
> commands that I type on the keyboard of the VT420 appears on the screen of
> the VT420 (except the password, of course), but anything that the microVAX is
> sending to the VT420 appears as garbage. There are recognisable characters,
> but if I TYPE a file, even a small one, what appears seems to be every 7th
> character from the file starting with the first character. The output of
> commands such as DIR appear to have the same problem. ...
> ___
> Simh mailing list
> Simh@trailing-edge.com
> http://mailman.trailing-edge.com/mailman/listinfo/simh
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Re: [Simh] Problem using a real VT terminal with simh

[Paul Koning]

Do you have flow control (Xon/Xoff) enabled both on the terminal and on the VAX?

You might try a slower speed to see if that makes a difference.  It shouldn't, 
but it might give more information.

Is autobaud enabled on the line?  You might turn that off and set the speed and 
related parameters explicitly.

paul

> On Dec 5, 2017, at 12:56 PM, Peter Allan  wrote:
> 
> I am trying to get a real VT420 terminal working with a simulated micro VAX 
> 3900. However, I am having problems getting text displayed on the screen of 
> the VT420.
> ...
> Once the microVAX has booted, if I hit Enter on the VT420, then I can see 
> that a login process starts on the simulated microVAX, but all I see on the 
> screen of the VT420 is a few garbage characters. Despite that, when I type a 
> username and a password, I do get logged into the simulated microVAX. Any 
> commands that I type on the keyboard of the VT420 appears on the screen of 
> the VT420 (except the password, of course), but anything that the microVAX is 
> sending to the VT420 appears as garbage. There are recognisable characters, 
> but if I TYPE a file, even a small one, what appears seems to be every 7th 
> character from the file starting with the first character. The output of 
> commands such as DIR appear to have the same problem. ...
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