I built something similar: https://bbenchoff.github.io/pages/dumb.html

What are you going to do about the actual cost of the device? You've already got an e-paper display, but you're also adding a 'laptop' style enclosure, real keyboard, and if you're storing SSH keys, you're really close to running a cut-down Linux system. That's basically a laptop, and you could get the same thing with, you know, a laptop. Have you thought about scaling down the display, keyboard, and enclosure to something palm-top sized?

That is very cool! Have you built a physical copy of it?

No, I think the smaller size is probably a non-starter for the intended audience. This is meant to be a tool that a lot of these folks are using for hours and hours a day so overall typing and reading experience is paramount, and meant to be a "selling" point.

Cost-wise, yes--we're still grappling with costs of the e-ink screen. It's the by far the largest expense in the unit. We've got a good lead that I unfortunately can't talk about at the moment (under NDA).

A cut-down Linux really is overkill for this, and isn't capable of making some of the other specs happen (battery life, availability), at least as far as we've been able to determine. Custom code is unfortunately where we've been forced to go.

The other reason not to run Linux is because the ESP32's a bit underpowered to run Linux (lacks an MMU). Slightly more powerful hardware (eg Raspberry Pi Zero) would do better, and get you a working device far sooner, which would be great for testing out some of the other components while waiting for getting the software written.

Embedded Linux (eg any distro using busybox for glibc) is (imo) the appropriate stack to use for this given how cheap a microcontroller with an MMU is these days, and once you get rid of all the bloat, is capable of very quick boot times (availability), and if the device is off (and not just sleeping), then its battery life is similarly extended. (Don't let the poor battery life of Android phones let you believe Linux isn't capable of long battery life. Smartphones don't actually get to sleep while the screen is off.)

The ESP32 is getting replaced with a better microcontroller (it's down to either an upcoming STM32 ultra-low power or the upcoming Ambiq Apollo4 depending on how well they perform in real life), but ESP32 was what we started with given familiarity and availability.

Remember, the device can sometimes have enough time to sleep BETWEEN keystrokes while typing. (The microcontroller can sleep then wake and power up peripherals with only a tiny, imperceptible delay.) This isn't your typical Linux setup. FreeRTOS is plenty. For the limited things it does, it wants to be a no-compromise device. There is no on button. There is no off button. You grab the device, it has an image on the display because it's e-ink and you start typing. Assuming you've previously connected to a remote device the system will have done what's necessary to keep that connection alive (invisibly waking as needed). Your keystrokes can go through right away to the remote connection. Your results will hit the screen right away too. The device is always on and it is always off, if that makes sense. There's more to it--bits of stuff and bother and implementation details--but I hope this gives you the idea.

Honestly, 13" is more than you need for a 4:3 terminal. A lot of classic character terminals had 9 or 10 inch screens...it's not until you get to like the VT320 that you have a 14" screen. I'd consider a 10 inch screen about ideal, and the keyboard doesn't have to be 13", either.

We are making prototypes in 3 different 4:3 sizes--10.3, 12.1, and 13.3. 13.3 is furthest along. The end of your comment talks about the real size restriction for us--keyboard. We do not want to compromise the typing experience.

Around 12" (in a 4:3 body) is about as low as you can go without messing with the typing experience much. The problem at that size is the available e-ink panels are S-L-O-W; no fast refresh models are out there.

(You might ask why we would even do the 10.3" prototype if we know that's too small for keyboard reasons? It's mostly for marketing reasons when we actually try to try to get attention for this project. The 10.3 is going to use a Thinkpad 701c butterfly keyboard in a custom body just for the "wow!" factor in showing the sorts of things that are possible. The 10.3 would actually be a killer end-product, but no similar keyboard is in current production so we couldn't actually make it).

Have you considered using a DES display or Sharp Memory LCD? I know the first is definitely cheaper than a branded E-Ink display, and the latter has much faster refresh rate and may be more suited to being a terminal (and may also be cheaper than E-Ink, I just haven't looked into it).

Yes we have considered it. Do you know of any such large (over 12 inches) panels with decent resolution and pretty fast updates that are available? Such a thing would probably help with power consumption. (e-inks consume a lot of power during screen updates).

Looking at all of the options a simple full RLCD would probably be best for us--not eink--but we can't find appropriate parts for the size and resolution.

I know that the DES displays go up to 10.1", but I haven't seen displays beyond that size (though I'm unsure if they intend to make larger displays in the future). For the Sharp Memory Displays, I think I may have spoken too soon - looks like they top out at 4.4" currently, which of course wouldn't work for your application.

RLCD is an interesting option, I guess the sacrifice there is readability angles and paper-like-ness?

Ones with good viewing angles exist, but for sure there isn't paper-like-ness and you loose the no zero-power persistence of e-ink. But you get fast, artifact-free refreshes, perfect sunlight readability, at very low power consumption. (No backlight which can be a pro and a con...if only a more modern Pixel Qi type panel existed.)

Do you estimate thay this concept will ever come to life? (say, P1) If so, when?

(I'm OP, sorry for unsolicitedly posting your notes to HN. I guess I am just a bit too excited for this)

We have a prototype-y thing part way between P0 and P1 already.

A "you can build it yourself" P1 version of that will probably be well-documented by early next year, but it won't be something you can just go out and buy yet. You'll have to gather together the parts needed, get the PCB produced, etc.

The plan was for us to get something to that P1-stage and then go more public about the project. No worries on jumping the gun with posting it. It's not exactly a secret, just not *intended* for public consumption yet.

I think when we have a couple of copies of P1s ready to show off (and videos of the product, and an actual product website! :-) having something put together we can show off would help open up some doors from people with more experience with getting hardware produced so people can get this more readily (even if just in kit form to start). Right now we're just doing one-off prototyping.

I realize this might simply put me into the "not target demographic" group, but what makes this so useful as a terminal, that a laptop won't do?

I could understand the no-distraction writing i.e. word processor use-case that some people think E-Ink would be good for, but that doesn't appear in your list of possible applications either.

Use as a distraction-free word processor is listed as a use-case if you read far enough. (As mentioned, the notes are a bit of a mess and weren't cleaned up for public consumption.)

But, yes, a laptop can do pretty much everything Paperterm can do. A laptop can do everything a Kindle can do. A laptop can do a huge percent of what your phone can do. If the advantages of this niche device (e.g., sunlight-readable display with no backlight/blue-light, it's insane battery life, a no-compromise keyboard, and it's always-ready-"never-off" state) doesn't appeal to you, then you're right, you're probably just not in the target demographic. Those in the target market find a lot to love in such specs. This is explicitly a niche product, not trying to be everything for everyone (which is closer to what a laptop does).

EDIT: if you have a look at the (also not ready for announcement) root of the domain, you'll see a brief pitch: http://www.paperterm.org/ This page also has notes-to-self in brackets, and I'm not in a spot where I can fix it right now, so ignore that.

I would be pretty close to the exact target for this product. The killer feature that would put it over the edge for me would be the possible "crashcart" KVM feature mentioned later in the notes.

Lugging around a full KVM console is overkill (unless it is literally on a cart and you only need it at one location). And USB crash cart adapters are buggy, overpriced, and unmaintained.

With serial, SSH, and KVM this will fill the perfect "there is a piece of hardware on the rack I need to interface with" role.

A distraction free word processor that could display PDFs along with the text (for writing LaTeX) would be a real godsend for me. In fact I am writing this very comment while distracting myself from some LaTex I am supposed to be writing...

You could probably do that with a cheap laptop by cutting down a Linux distro then removing/breaking all network hardware antennas/ports

I think this would be great for the same reason that using a Remarkable tablet is great.

Exactly because it is limited in it’s application.

There is also this project, might be interesting to get in touch: https://hackaday.io/project/179890-india-navi

For sure! Thank you for the pointer to it.

Sounds like a very interesting project, I certainly would be tempted to have an eInk terminal. Can you post images on how the terminal looks on the eInk screens?

I can give you images of how a terminal looks on e-ink screens but not with the final panel we're likely to use nor with final software, so probably best no to since it wouldn't be representative.

Google can give you an idea of how it looks, but with a much smaller screen than we're using (ours is 13.3") so these images feel more cramped and look more "plain jane": https://www.google.com/search?q=e-ink+terminal&um=1&ie=UTF-8... With the larger screen and more refined setup than these Google Images pictures show, it is very pleasant to use. I hands-down prefer it to a laptop running a terminal, except when color is important.

Does the e-paper display you use have to "flash to black" on just about every change like so many of the Kindle whites do?

Our panel supports partial refresh (no black flash) which makes it much more performant. The software does have to do occasional flashes to keep the screen tidy (otherwise you get a lot of ghosting over time). You can control how often this happens.