@larsbrinkhoff https://github.com/larsbrinkhoff/sixel/blob/master/vt220.txt says "This has been tested on a real VT220", but has it been tested on an emulated #VT220? I can't find an emulator that supports VT220-style sixels, and I'd love to be able hack on programs targeting the VT220 when I'm away from my desk.

#DOOM on my #VT220... at about 0.6 FPS... gotta try to optimize the screen update code.

#retrocomputing Some Digital Equipment Corporation (#DEC) terminal history...

This first part oddly enough arriving via an iOS development newsletter, Dave Verwer's iOS Dev Weekly...

Here is a TrueType font simulating the DEC #VT220 font:

http://sensi.org/~svo/glasstty/

For those further interested in this old fonts topic, there's a copy of the actual DEC VT terminal fonts extracted from the DEC VT terminal firmware embedded in the #VTstar terminal emulator package.

VTstar was a port of the DEC VT terminal firmware to a (now ancient) version of #Microsoft #Windows and built as a terminal emulator.

It is for this reason a quite accurate emulation of a DEC VT terminal.

There's a copy of VTstar (alas, binary only) included on the #OpenVMS Freeware from many years ago:

https://www.digiater.nl/openvms/freeware/v70/vtstar/

This VT220 TTF fills me with nostalgia.

http://sensi.org/~svo/glasstty/

#dec #font #vt220 #terminal

A discussion (linked below) of serial line #break signals reminded me of an era of #computinghistory / #retrocomputing when those break signals were far more common...

A serial line break signal is effectively a serial line framing error. The bits aren't where they should be, and the clocking bits are wrong. As with other things in computing, sometimes errors are (re)used for other not-error purposes.

Many old serial terminals such as the #DEC #VT100 terminal had a dedicated break key, and there was the F5 key on a #VT220 terminal LK201 keyboard, and this key generated and sent the framing error. The break.

Why deliberately send an error?

Because a cheap #UART chip in the serial port hardware could easily detect that framing error.

A UART that could detect the arrival of a specific serial line character, say ^P to perform some action, cost rather more. And vendors of lower-end servers tended to prefer lower-end parts.

Which meant that some inexpensive computer servers—inexpensive servers for the 1980s and 1990s era, that is—used a cheap UART for their console control port—a console serial line allowed server management by serial line—and which meant the server could detect and use the break to interrupt the server processing, such as halting a stuck operating system.

This then also meant that an errant break on the console could halt the server.

And of course a DEC VT terminal and various other serial terminals also tended to generate framing errors on first power up. Not just when the break key was pressed.

Which then halted the server.

Adding more complexity to this console break usage, some operating systems (including #VAX/#VMS and #OpenVMS) also used break to defeat password-grabbing apps.

Yes, password-grabbing apps have been around for a long time. Well before the era of Control-Alt-Delete, another means to thwart a password-grabbing app

You'd enter a break, or the C-A-D, and the logged in session would be terminated.

Usage which then caused the very obvious problem for a serial console of course, just as soon as somebody entered a break on the serial console line.

With some systems, you could continue a halted system if you entered the continue command quickly enough. If not, welcome to a server reboot and grumpy users.

In a more recent era, terminals and terminal emulators and keyboards generally lack break keys. So either the terminal emulator needs a break function in its menus or some other chord, or you'll need some other approach when using the so-called secure server login feature (this feature has largely disappeared, given telnet (boo!) ssh (yay!) logins get a new session), or to trigger a halt on a console with a break-expecting UART.

Now if you've been following along, maybe a rather more baudy tale has occurred to you: a serial line framing error can also be generated by changing the terminal setting for the serial line speed. Switch speeds, press a few characters, reset the speed back to the correct value, and you should be looking at the aftermath of a break signal.

Sending ^P to a console—for those old VAX and ilk that expect a ^P—to halt the server is just far too easy.

But switching serial speeds to trigger a halt... works. Sometimes when you don't want it to.

http://rachelbythebay.com/w/2022/12/25/tty/

"You're all so young! Why, I bet some of you have never even used a serial connected terminal!" #VT220

First toot from a #DEC #VT220! (Pic hopefully to follow.)

It's my one piece for #retrocomputing... a tempermental beast.

The font doesn't scale well but in its original size or integer multiples of that
sure has charm and triggers memories.

https://github.com/svofski/glasstty
https://web.archive.org/web/20220821094225/http://sensi.org/~svo/glasstty/

#font #ttf #vt220

The first images I downloaded from #NASA were from their #gopher server in 1992 or 1993 when I was at college - got them using a DEC #VT220 (Uni had plenty of those) so I could view them later on one of the limited number of #SPARCstations. Was so tempted to buy one of those a few years ago when they were cheap. #retrocomputing

Also it's tagged at vt200 but it's obviously a #vt220 whoops

My favorite #vt220 like device for hacking and #retrocomputing is the Random Corporation's Colleague. The (heh) Random Colleague was built when people had the need for mobile access to computing but you were really just dialing into a more powerful computer. It has a word processor that saves to volatile memory because you're just going to transfer it to the real computer later. It has a built in modem that'll do up to 1200 baud (bell212a) and supports serial up to 19.2k. Battery is leadacid.

@kelbot @nytpu @robert588 It's #classic #amber #Unscii #dec #vt220 style!!

#astronomie #science

Reportage datant de 1998 sur l'astronome suisse #MichelMayor co-découvreur en 1995 de la première #exoplanète, la géante gazeuse chaude #51Peg depuis l'#ObservatoireDeHauteProvence. À la base Michel Mayor recherchait des naines brunes et non des planètes.

Informatiquement, un #TerminalX pour l'analyse et l'affichage graphique des résultats et des #vt220 pour le contrôle des instruments.
➡http://www.universcience.tv/video-au-dela-des-etoiles-7385.html