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Comment by chrisper | Hacker News Reader

Does anyone know how they did the user interface? I mean I could read the source code, but I am asking for a TL;DR if someone has that.

EDIT: Actually it seems to be a library: https://github.com/jroimartin/gocui but the question still stands!

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If you mean the general principle of this kind of pseudo-GUI in text mode, look into codepage 437 [1]. It's possible to do more advanced stuff with custom glyphs [3], but it doesn't look like this does anything like that - it generally requires direct hardware access to modify the font.

This was a pretty common technique in 90s DOS programs, but it can be tricky to get working cross platform over a serial terminal. The library you found seems to rely on termbox [2] for that.

[1] https://en.m.wikipedia.org/wiki/Code_page_437

[2] https://github.com/nsf/termbox-go

(edit)

[3] I thought Norton Commander did this, but I was mistaken - it just uses codepage 437. It was Norton Utilities [4].

[4] https://en.m.wikipedia.org/wiki/VGA-compatible_text_mode

Non mobile links:

[1]: https://en.wikipedia.org/wiki/Code_page_437

[4]: https://en.wikipedia.org/wiki/VGA-compatible_text_mode

For UNIX-style terminals, there are also VT-nnn (can't remember the nnn) line drawing commands, and Unicode line drawing characters.

My favorite DOS app that modified the VGA font was Impulse Tracker. It could actually draw oscilloscopes in text mode, and its source code is available.

https://en.m.wikipedia.org/wiki/Impulse_Tracker

You found the library. Looks like simple math stuff. Neat.

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