Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Integrating a VT220 into my life

drewdevault.com

Post reply on HN
Print view View original

51–60 of 125 posts

Re: Integrating a VT220 into my life

#51

Post by AceJohnny2 »

The VT220 is fascinating as an example of "old" computer technology that still influences the devices we use on a daily basis.

I've recently had to understand exactly which control characters are sent between the app and the terminal (emulator) for delete and backspace.

Guess which ASCII control characters is sent by the Backspace key on your PC keyboard? ASCII DEL (0x7F/^?)! All modern terminal emulators on Linux and OS X (including the Linux console, xterm and libvte-based terminals, OS X Terminal.app and iTerm2) now default to sending DEL [1] when you press the Backspace key... now it makes much more sense that on a Mac keyboard, that key is labeled "Delete" and used to have the same symbol as on the VT220!

Oh, and what character is sent when you press the (forward) Delete key? Why, the escape sequence 1B 5B 33 7E (ESC [ 3 ~), of course :) Because the terminals we emulate didn't have a key for forward delete ;)

For bonus credit, lookup the historical usage of the Linefeed (LF/0xA/^J) and CarriageReturn (CR/0xD/^M) characters [2]. There was much more than just the Unix/Mac/Windows divide in text files...

[1] yes, you can swap for ASCII BS (8/^H), but if your app needs that, consider updating it.

[2] https://en.wikipedia.org/wiki/Newline#Representations

Re: Integrating a VT220 into my life

#52

Post by rikkus »

tacostakohashi wrote: post #15

I had a Wyse dumb terminal attached to my main Linux workstation for a few years in the late 90s, back when such things were fairly easy to pick up for free. Its not to be sneezed at for doing serious programming work. The green on black, text only CRT was super high contrast (especially compared to any modern LCD), and the complete lack of distractions that come with a multitasking desktop environment (email notific…

Wyse attached to my Linux workstation in the late 90s too.

My Linux workstation's monitor was mainly in text-mode too. I used the Wyse to tail some logs and used vim and a shell for 'real' work on 2 VTs, with IRC and mutt on a couple more.

All this talk about how expensive serial terminals are now makes me think I should have kept some of the hundreds I threw away over the years, but then I think about the storage required!

Re: Integrating a VT220 into my life

#53

Post by Syrup-tan »

creshal wrote: post #31
paulmd wrote: post #30

Quasi-related: I've always wanted an ultra-low-power dumb terminal using eInk paper displays - something you could hit days of runtime with using a small battery pack. eInk uses no power when they're not updating - so idling or long-running operations would hardly use any power. So far the easiest approach I've found is using a hacked Kindle with an attached keyboard. You can run a terminal client on it and ssh into…

I'd really love to have one or five of those for maintenance work. There's a lot of devices that I don't really need to have a keyboard and video connected to for 99.99% of their life time, but I still need an LC display and KVM switch connected to for about 10 minutes per decade. It's such a waste.

Euhh, I'm not sure I understand your use-case, but e-ink displays aren't especially "cheap", or such. They take a noticeable amount of time to update the display, so doing things like typing, or viewing output from top(1) would be less than ideal. (This seems to get better with firmware, and being "smart" about which places of the screen get updated, generally)

The appeal, at least to me, is that they can display information with little energy cost. For example you could have it monitor the system's health and have it update every half an hour, showing graphs and such, and it would be able to do that for a very long time with a smallish battery.

Re: Integrating a VT220 into my life

#55

Post by bjackman »

aperrien wrote: post #46
paulmd wrote: post #30

Quasi-related: I've always wanted an ultra-low-power dumb terminal using eInk paper displays - something you could hit days of runtime with using a small battery pack. eInk uses no power when they're not updating - so idling or long-running operations would hardly use any power. So far the easiest approach I've found is using a hacked Kindle with an attached keyboard. You can run a terminal client on it and ssh into…

As an aside, do you have an idea where to buy e-ink displays? I'd love to experiment with some. If fact if I could I'd love to get one of the poster sized ones!

Sparkfun sell small ones in kits.

Re: Integrating a VT220 into my life

#56

Post by rcarmo »

Wow. I used VT220s and 230s in college, and remember those days fondly (they were hooked up to VAXen, and there was nothing quite like it, really).

I wonder if I could get a keyboard and enclosure someplace and bolt on an LCD panel from a netbook (if only for the sake of power consumption).

Re: Integrating a VT220 into my life

#57

Post by clevernickname »

Bud wrote: post #34
paulmd wrote: post #30

Quasi-related: I've always wanted an ultra-low-power dumb terminal using eInk paper displays - something you could hit days of runtime with using a small battery pack. eInk uses no power when they're not updating - so idling or long-running operations would hardly use any power. So far the easiest approach I've found is using a hacked Kindle with an attached keyboard. You can run a terminal client on it and ssh into…

Wouldn't the very slow refresh rate of eInk be an issue here?

I suspect it would. I ended up giving away my Kindle partly because the delay in page turning[1] was long enough to bother me. I can't imagine typing with such a display.

An article on here a little while back goes into detail about how even very small latencies affect the typing process: https://news.ycombinator.com/item?id=10787812

[1] Yes, I know it takes longer on an e-ink display to refresh the entire screen than to update a single character. My point is that page turning speed is thought by most to be unimportant, but being used to PC interfaces with fast response times made it unbearable to me, especially when I was skipping through pages trying to find something.

Re: Integrating a VT220 into my life

#58

Post by ChuckMcM »

I've long since given away or sold most of my old DEC terminals, I've still got a couple (VT340, VT340+, VT220 x 2) but the keyboards don't hold up. I'm down to two working keyboards (an LK201 and an LK401). I've been tempted to wire up a HID -> VTxx adapter using a simple embedded controller. I'll have to add that to my list of fun projects for a long weekend.

Generally though when using them on older machines I am amazed at how frustrating 80 columns of 24 (or 25) lines can be! Sure you can do "wide" mode and get 132 columns but still, the desire to see more screen real estate is a constant issue.

Re: Integrating a VT220 into my life

#59

Post by tmm »

aperrien wrote: post #46
paulmd wrote: post #30

Quasi-related: I've always wanted an ultra-low-power dumb terminal using eInk paper displays - something you could hit days of runtime with using a small battery pack. eInk uses no power when they're not updating - so idling or long-running operations would hardly use any power. So far the easiest approach I've found is using a hacked Kindle with an attached keyboard. You can run a terminal client on it and ssh into…

As an aside, do you have an idea where to buy e-ink displays? I'd love to experiment with some. If fact if I could I'd love to get one of the poster sized ones!

Visionect (https://www.visionect.com/) sells e-ink dev kits up to 32 inches, but they aren't exactly priced for experimentation (nor do they include any sort of case/bezel). On the other hand, their displays do come with Ethernet, Wi-Fi and cellular connectivity built in.

Re: Integrating a VT220 into my life

#60

Post by aexaey »

paulmd wrote: post #30

Quasi-related: I've always wanted an ultra-low-power dumb terminal using eInk paper displays - something you could hit days of runtime with using a small battery pack. eInk uses no power when they're not updating - so idling or long-running operations would hardly use any power. So far the easiest approach I've found is using a hacked Kindle with an attached keyboard. You can run a terminal client on it and ssh into…

1mA/MIPS is a pretty generous power budget, with ESP8266 easily fitting the bill (56mA @80MHz + wifi rx; 10 uA in deep sleep [1]). Talking of which - here is Jeroen Domburg's project where he used exactly this chip to make a wireless battery-powered e-ink display:

[0] http://spritesmods.com/?art=einkdisplay

[1] http://bbs.espressif.com/viewtopic.php?t=133

Post reply on HN