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Ansi/Line drawing chars does not work properly in the terminal #23791

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opened 2026-01-31 08:52:39 +00:00 by claunia · 5 comments
claunia commented 2026-01-31 08:52:39 +00:00
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Originally created by @kalleswe on GitHub (Nov 9, 2025).

Originally assigned to: @lhecker on GitHub.

Windows Terminal version

1.23.12811.0

Windows build number

10.0.19045.6456

Other Software

telnet.exe within command line in terminal.

Steps to reproduce

telnet to any bbs and you will see that ansi is messed up or line drawings as well. also telnet/terminal doesn't support inline zmodem which it should. please fix.

Expected Behavior

Expecting terminal to render ansi screens like this:

Image

Actual Behavior

But instead the acucal behavior of the terminal is:

Image

Which is totally bad.

Originally created by @kalleswe on GitHub (Nov 9, 2025). Originally assigned to: @lhecker on GitHub. ### Windows Terminal version 1.23.12811.0 ### Windows build number 10.0.19045.6456 ### Other Software telnet.exe within command line in terminal. ### Steps to reproduce telnet to any bbs and you will see that ansi is messed up or line drawings as well. also telnet/terminal doesn't support inline zmodem which it should. please fix. ### Expected Behavior Expecting terminal to render ansi screens like this: <img width="800" height="359" alt="Image" src="https://github.com/user-attachments/assets/4fa0b96f-c190-4b8b-9c3b-f626378ef1cd" /> ### Actual Behavior But instead the acucal behavior of the terminal is: <img width="882" height="479" alt="Image" src="https://github.com/user-attachments/assets/ea434ee2-cb37-4327-b594-2fa2f6533ae5" /> Which is totally bad.
claunia added the Issue-BugPriority-3Resolution-ExternalNeeds-Tag-Fix labels 2026-01-31 08:52:39 +00:00
claunia commented 2026-01-31 08:52:40 +00:00
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@lhecker commented on GitHub (Nov 11, 2025):

telnet to any bbs and you will see that ansi is messed up or line drawings as well.

Can you name us a specific BBS we should try? Generally speaking, these invalid characters indicate an encoding issue:

Image
@lhecker commented on GitHub (Nov 11, 2025): > telnet to any bbs and you will see that ansi is messed up or line drawings as well. Can you name us a specific BBS we should try? Generally speaking, these invalid characters indicate an encoding issue: <img width="184" height="93" alt="Image" src="https://github.com/user-attachments/assets/c22ee228-5359-4aef-ab9e-b3b0d1201c47" />
claunia commented 2026-01-31 08:52:41 +00:00
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@j4james commented on GitHub (Nov 13, 2025):

I think the problem here is that the telnet client that comes with Windows has its own escape sequence processor, and it's not very good. I get much better results using telnet from within a WSL shell.

I was kind of surprised actually, because I expected most BBSes would required a 437 code page, but at least some of them seem to be fine with UTF-8.

I couldn't find the Spiderman example, but here's one BBS which has a similar kind of artwork on the login screen:

telnet cqbbs.ddns.net 6800

With the Windows inbox telnet.exe it looks broken, but if you telnet from a WSL shell it looks fine.

@j4james commented on GitHub (Nov 13, 2025): I think the problem here is that the telnet client that comes with Windows has its own escape sequence processor, and it's not very good. I get much better results using telnet from within a WSL shell. I was kind of surprised actually, because I expected most BBSes would required a 437 code page, but at least some of them seem to be fine with UTF-8. I couldn't find the Spiderman example, but here's one BBS which has a similar kind of artwork on the login screen: ``` telnet cqbbs.ddns.net 6800 ``` With the Windows inbox telnet.exe it looks broken, but if you telnet from a WSL shell it looks fine.
claunia commented 2026-01-31 08:52:41 +00:00
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@lhecker commented on GitHub (Nov 17, 2025):

I think the problem here is that the telnet client that comes with Windows has its own escape sequence processor, and it's not very good.

[scrubbed]

The only thing I find confusing is that the internal conhost.exe repository contains a directory named "telnet" and I had assumed it's being used for this. Perhaps it was only a test project? I should suggest that we replace the old tcpip/telnet client with a modern one.

@lhecker commented on GitHub (Nov 17, 2025): > I think the problem here is that the telnet client that comes with Windows has its own escape sequence processor, and it's not very good. [scrubbed] The only thing I find confusing is that the internal conhost.exe repository contains a directory named "telnet" and I had assumed it's being used for this. Perhaps it was only a test project? I should suggest that we replace the old tcpip/telnet client with a modern one.
claunia commented 2026-01-31 08:52:42 +00:00
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@lhecker commented on GitHub (Dec 3, 2025):

I know where the telnet client code is and try to fix it. Not sure when, but I'll see if I can squeeze this in somehow.

@lhecker commented on GitHub (Dec 3, 2025): I know where the telnet client code is and try to fix it. Not sure when, but I'll see if I can squeeze this in somehow.
claunia commented 2026-01-31 08:52:42 +00:00
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@juliannoble commented on GitHub (Dec 21, 2025):

I think the problem here is that the telnet client that comes with Windows has its own escape sequence processor, and it's not very good. I get much better results using telnet from within a WSL shell.

I was kind of surprised actually, because I expected most BBSes would required a 437 code page, but at least some of them seem to be fine with UTF-8.

I couldn't find the Spiderman example, but here's one BBS which has a similar kind of artwork on the login screen:

telnet cqbbs.ddns.net 6800

With the Windows inbox telnet.exe it looks broken, but if you telnet from a WSL shell it looks fine.

Using terminal canary 1.25.3531.0 and a custom telnet client - this BBS renders nicely - I can navigate the menus and view other ANSI images on the board, confirming it's likely an issue with the telnet.exe client.

@juliannoble commented on GitHub (Dec 21, 2025): > I think the problem here is that the telnet client that comes with Windows has its own escape sequence processor, and it's not very good. I get much better results using telnet from within a WSL shell. > > I was kind of surprised actually, because I expected most BBSes would required a 437 code page, but at least some of them seem to be fine with UTF-8. > > I couldn't find the Spiderman example, but here's one BBS which has a similar kind of artwork on the login screen: > > ``` > telnet cqbbs.ddns.net 6800 > ``` > > With the Windows inbox telnet.exe it looks broken, but if you telnet from a WSL shell it looks fine. Using terminal canary 1.25.3531.0 and a custom telnet client - this BBS renders nicely - I can navigate the menus and view other ANSI images on the board, confirming it's likely an issue with the telnet.exe client.
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