Things I've learned building a modern TUI Framework (2022)

Anyone old and naiv enough to share this observation: Almost everything I looked at after TurboVision was inspired, but actually not really finished. Once you take the toolkit for a ride, you realize its kind of cute but unfinished. Maybe another way of looking at this is to call many of the TUI frameworks I say "opinionated", whatever that exactly means.

I am likely just dense and uncreative, but the truth is, when I switched from DOS to Linux in the 90s, I was never again as productive as I happened to be with B800. Granted, it likely took me a long time to understand the need for double buffering and the difference between a local/direct text mode vs a terminal, let alone escape sequences. But still. Whenever I tried to do something directly in ncurses, I pretty much gave up due to a distinct feeling of being unhappy. Completely different to what I was able to do with the simple ideal of B800.

I learned GUI programming using win16, then win32 — this would've been during the transition to WinXP. I must have a city-wide blind spot, but every post message pump GUI framework has left me completely befuddled. One thing I never understood was how these OO frameworks helped to really solve the multithreaded UI issues. In Win32, I just threw the main renderer into a thread, then had support renderers build models "on the side", and then updated the difference. The code never really got out of hand.

I get what Turbo Vision is (was), but what's that B800 thing? Surely you aren't talking about a Celeron processor? Seems tricky to google, also no Wiki page on that. You got me curious, plz spill it! =)

Ok I think he’s referring to 0xB800, the VGA text buffer segment in real mode.

In real mode addressing and graphic card in text mode, your video memory started at absolute address 0xb800:0x0000. It was an two-dimensional array, where you could poke and whatever you changed here, was reflected immediately on the display. Each element of the array was two bytes: character itself and color attributes.

0xb800 is the address of the framebuffer for text. Simply write characters to that address, using offset `((row * width) + col)` and they'll appear on screen.

In graphics mode it was, IIRC, 0xa000. I once wrote a pacman-type easter egg inside the point-of-sale system[1], because doing direct graphics straight to an address is so easy and simple.

[1] Was removed after pilot and before actual release.

No not VGA, CGA actually

I think it is also 0xb800 as it is a physical address; not ionly in real mode.

For physical linear address, it would be one digit (4-bits) longer (-> 0xb8000); when the segment:offset is combined, the result is 20-bit address.

Was not my point though.