[Simh] Problem using a real VT terminal with simh

[Peter Allan]

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=4
ATTACH 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

[Paul Koning]

This post might be inappropriate. Click to display it.

[Mark Pizzolato]

Post by 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.

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.

Post by Paul Koning

Post by Peter Allan
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.

Post by Peter Allan
...
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
http://mailman.trailing-edge.com/mailman/listinfo/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

Post by Paul Koning

Post by Paul Koning
Do you have flow control (Xon/Xoff) enabled both on the terminal and on

the

Post by Paul Koning
VAX?
You might try a slower speed to see if that makes a difference. It

shouldn't,

Post by Paul Koning
but it might give more information.
Is autobaud enabled on the line? You might turn that off and set the

speed

Post by Paul Koning
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.

Post by Paul Koning

Post by Peter Allan
I am trying to get a real VT420 terminal working with a simulated

micro VAX

Post by Paul Koning
3900. However, I am having problems getting text displayed on the screen

of

Post by Paul Koning
the VT420.

Post by Peter Allan
...
Once the microVAX has booted, if I hit Enter on the VT420, then I can

see

Post by Paul Koning
that a login process starts on the simulated microVAX, but all I see on

the

Post by Paul Koning
screen of the VT420 is a few garbage characters. Despite that, when I

type a

Post by Paul Koning
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

Post by Paul Koning
the VT420 (except the password, of course), but anything that the

microVAX is

Post by Paul Koning
sending to the VT420 appears as garbage. There are recognisable

characters,

Post by Paul Koning
but if I TYPE a file, even a small one, what appears seems to be every

7th

Post by Paul Koning
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
http://mailman.trailing-edge.com/mailman/listinfo/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:***@gmail.com]
Sent: Tuesday, December 5, 2017 12:39 PM
To: Mark Pizzolato <***@infocomm.com>; ***@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

Post by 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.

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.

Post by Paul Koning

Post by Peter Allan
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.

Post by Peter Allan
...
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
http://mailman.trailing-edge.com/mailman/listinfo/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

Post by 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

Post by Peter Allan
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.

Post by Peter Allan
...
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
http://mailman.trailing-edge.com/mailman/listinfo/simh

[Hittner, David T [US] (MS)]

It sounds like the serial port is trying to autobaud to determine the transmission speed. I would set the port forcibly to 9600 8N1 before connecting.
SIMH does not set the baud on the real physical port AFAIK, it just interprets the characters 7b/8b.

Dave

From: Simh [mailto:simh-***@trailing-edge.com] On Behalf Of Peter Allan
Sent: Tuesday, December 05, 2017 12:56 PM
To: ***@trailing-edge.com
Subject: EXT :[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=4
ATTACH 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

[Robert G. Schaffrath]

Several years ago I wanted to hookup and old VT320 that I have and I did
manage to get it to work but I did not go with the direct serial I/O
connection in SiMH. Instead I found a program called TCPToSer that
established a TCP/IP connection from the serial port. It worked fine with
a USB to serial adapter that I had and I pointed the application at my SiMH
TCP/IP port. This was way back in the mid-2000's. The application was
available from www.tcptoser.de but that URL is now dead. A search did turn
up a download from a site starting with "brother" but it is infected with
Win32/Spursint.F!cl. If a clean copy of that software can be found, it
does work beautifully with SiMH. I was able to navigate around EDT very
nicely using the GOLD key and various sequences my fingers still remembered
LOL.

---------- Forwarded message ----------
Date: Tue, 5 Dec 2017 17:56:29 +0000
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=4
ATTACH 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

[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 <***@gmail.com> Date: 12/5/17 1:38 PM (GMT-07:00) To: Mark Pizzolato <***@infocomm.com>, ***@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

Post by 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.

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.

Post by Paul Koning

Post by Peter Allan
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.

Post by Peter Allan
...
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
http://mailman.trailing-edge.com/mailman/listinfo/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 <***@gmail.com> Date: 12/5/17 10:56 AM (GMT-07:00) To: ***@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