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Comment by jonahx | Hacker News Reader

Could anyone knowledgeable about this explain what you can do with a jailbroken kindle that you cannot do with a locked one?

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I like to be able to read books in other formats (FB2 is a prime example) and use custom readers (e.g., I like coolreader for its configurability). I think neither is an option with Kindle, so I use a rooted Nook.

However, I like Kindle hardware a bit more, so I would probably switch if it can be unstuck from using the Amazon default software choices.

I've jailbroken mine to have custom covers. Instead of famous dead American authors I've never read, I have famous dead physicists whom I've actually read and whom I admire.

I'd love to do this using "pulp" science fiction book covers. I assumed that there was already a tutorial for this, but my Google-fu is weak. Did you use a guide or just DIY? What size/resolution image does the Kindle expect? Is there a filename format or a directory structure to use?

Here you go (there is a link on that page for latest Kindle's, this is for v. 1/2/3/4:

http://wiki.mobileread.com/wiki/Kindle_Screen_Saver_Hack_for...

Image format is grayscale 800x600 (bigger for Kindle DX) png or jpg. For best quality I recommend fiddling a bit with the color to grayscale work in Gimp or Photoshop, especially if the image has large areas with soft gradients. IIRC, running a selective Gaussian blur after grayscaling, and/or working the curves tool a bit before grayscaling, will improve problematic images quite a bit. Early models had only 4 grayscales, now they have 16. "Posterize" to 4 or 16 colors after grayscale in Gimp will give you a good idea of how the end result looks.

I think you want screensaver hacks. Here's one example, but there are others.

http://wiki.mobileread.com/wiki/Kindle_Screen_Saver_Hack_for...

Some people add their contact details to the screensaver images, so if you lose your kindle your contact details are the first thing someone who finds it will see.

Maybe a better hack would be to disable screensavers since they serve no purpose on an e-paper display and actually cost battery to switch from text -> screensaver -> text.

The better behavior would be to not flip the screen at all and keep it static, using no battery.

Maybe give those famous dead American authors a try. They're famous for a reason :)

I was being a bit flippant; they're not all American, and checking the list now I see I've actually read 5 out of 11 of them.

I wish the cover would be the cover of the kindle book I'm currently reading.

me too, its amazing how often I forget the book title and author when anyone asks..

As mentioned, I think the most popular use is for custom covers. Recent firmware versions show that Amazon might be slowly working towards this as a feature.

As the guy who wrote this, I don't use any of the addons. Just did it for fun.

Well, the kindle runs essentially Linux so by jailbreaking it you gain the ability to launch arbitrary code! Eg alternate pdf readers, games, ssh, vim and a lot more which can be very useful (especially the off reader KOreader)!

check out mobilereads forums if you want to know more about that, it's a vibrant community.

Is it usable in a beach situation, if you really need to hack away in bright sunshine?

This is precisely the scenario e-ink excels in.

This guy thinks so: https://tinyapps.org/docs/e-ink-monitor.html

Nice. I wonder if you could do away with the laptop altogether, and just use your phone with the Kindle, maybe with a bluetooth keyboard for the kindle (for some light work on a beach).

Or if there are any other e-ink tablets that run a full linux (cli) or Android?

There are eink readers that are easier to hack, like the Kobo, but they're all limited in that they're e-readers and have the minimal processing power to match. The only full on eink tablet I know of is this one[0] which technically doesn't exist yet. It's fully funded, though, so I'm excited to see if it actually ships.

[0]: https://www.indiegogo.com/projects/13-3-inch-android-e-reade...

That 13.3 e-ink tablet looks pretty tasty, I hope it materialises.

I suppose you could run VNC on your Android/Ubuntu phone, and just use the e-ink tablet as a thin client.

Maybe the slow redraw of e-ink would suck for real work, unless there are ways to make it more palatable for terminal work

That's a limitation of e-ink that has yet to be explored. The Dasung paperlike[0] is a usb driven eink screen. From what I've seen of it so far, the refresh rate is on par with other usb-driven monitors I've used. It's about good enough for editing text, but anything more gets old fast. I wonder how fast that monitor could be pushed if used displayport instead of USB.

I've been tempted to buy an eink dev kit and see how fast I can push the refresh rate without consideration for battery life. Alas, I can't justify the cost. Oh, and I've never done embedded programming or driver development before. I suspect that might be an issue. :D

[0]: https://www.indiegogo.com/projects/paperlike-world-s-first-e...

Using vim in 'noredraw' mode you don't need high refresh rate, 9600 baud is fine.

Well, I'd say even more - these days when usual attention span is like, I don't know, 5 seconds? having a device which is restrictive in this regard, might be a very positive experience.

> having a device which is restrictive in this regard, might be a very positive experience.

It's funny you should say that. A guy I know hired some programmers to come up with custom software for a hacked Boox. It was a universal inbox for twitter, reddit, facebook and email conversations. The idea was that it purposely forced him to focus on only one thing at a time to increase his attention span and reduce the "instant thrill" of web browsing.

He has this entire theory of 'low reward lifestyle' I find intriguing.

Then again, he didn't try to do any programming on it. I'm a big fan of keeping the write -> compile loop as small as possible.

Well, write-compile loop depends on language and what you do. Of course it would be horrible experience to e.g. hack some mostly undocumented record format in Lisp REPL into ad-hoc parser routine on the screen with 1Hz refresh rate. But we may find some activities almost opposite to that example. Like, write a code (in literate programming style preferably) of some sophisticated algorithm, well-thought before, especially in language that doesn't support REPL-style well - e.g. C, where you know the tests wouldn't help you much and accuracy (and focus) is a king. And we don't have a need to strictly oppose those both activities to each other actually. Playing with REPL at home, done this part of work ('the quick part'), then take an eInk and go out to the park to slow down and think about that part ('the slow and focused part') - that sounds good for me.

The 'universal conversation app' is would be great to have on its own merit.

There's more - Onyx Boox Max, Sony DPT-S1

What I'd like to see is someone get xterm in Tektronix 4014 emulation mode with $EDITOR to run on the Kindle Keyboard. Because e-ink screens are exactly like the old Tektronix vector displays, in that adding a character/line/dot to the screen is much faster than repainting the whole screen. Should make for a much more useable experience.

You can left-justify text, just like in actual books. That alone is reason enough to jailbreak, it baffles me why amazon are so tone-deaf regarding this.

I can tell you what I'd like to do with my Kindle, that's absolutely worth jailbreaking it.

I use it for my own .mobi files from a variety of sources, including books I wrote myself. I purchased mine and paid to have no advertising on it.

I would roll back to the previous operating system, which did not have advertisements on the homescreen and did not make me navigate two levels deep just to get past subfolders and a 'downloaded' option hiding my own books from me by default, and I would remove its ability to update itself or do anything via wi-fi.

I would just connect it via USB for all file management, and that would be perfect for me.

Needless to say, I'm really frustrated with the 'update' I never asked for OR installed, which has screwed up these things. I am very, very interested in what can be done with this jailbreaking. All the more as I don't wish ever to purchase a book through Amazon again, if this is the direction they're going. And they are, they obviously are.

One nifty trick that I found few people know about, is that you can upload your own .mobi books into the Kindle cloud. Just use the email that they provide to upload PDFs and the like.

Once the books are there, they show in your cloud collection and are available for download, same as Amazon-purchased books. Better yet, you will also get cloud sync across devices for current location, bookmarks etc - probably the most enticing reason to go down this route.

(Not sure if this is helpful to you, if you really prefer to manage files directly via USB. But might be helpful to someone else.)

The first thing I did was to turn off the wifi on my kindle, so I don't have to deal with upgrades or ads. And somehow I can add my own .mobi file to my kindle via usb. I added pdfs I converted to .mobi that way (with some software I found through a google search).

It sounds like you should just buy a different e-reader then. The kindle is not the right product for you.

I turned mine into a little status display, showing today's weather (and a few other geeky things, but that's the main one). The combination of very low power usage and readable e-Ink display is great. Also older models are very cheap -- mine was £50 including delivery.

You can find tutorials for doing this all over the place, eg https://www.youtube.com/watch?v=Oel08SDFyIY (not the particular one I used, but he's done a very similar job to mine).

You mean besides what was mentioned in the article?

Afaict, it's entirely a technical writeup about how to jailbreak. From the intro: "This document details the steps and thought processes I went through when developing the jailbreak. Ideally this will be a useful map or starting point for anyone looking at the system in the future".

I didn't find any information aimed at users of the Kindle about why they'd want to jailbreak.

I assume gp was talking about the 7th paragraph mentioning "whys" such as epub, fonts, screensavers:

>The mobileread community has done a great job developing extended functionality of the readers. Some of the more popular packages involve an open-source alternative reader with ePub support, a plugin to change fonts, and another addon to enable custom screensaver images.

Not related to this hack, but I did see a post from a guy once that hacked his girlfriend's kindle so the screen saver showed the cover of "Mein Kampf" as a prank.

I was thinking the same thing... I can only think of "bragging rights" or a learning experience.

Although I think this is what makes the (internet) world awesome at the moment. The author sounds like they were mucking around to see how far they could get. Put some thoughts down for others to read and who knows?

Whenever we're recruiting, we always look for interesting things a candidate has done. Something like this will easily get you a first interview...

Probabaly remove the ads from the subsidised version.

This part is easy. Just remove/replace the ad images and keep it on airplane mode.

I still plan to jailbrake when I get around to it

What I'd really like to see, personally, is Dropbox syncing over wifi with an arbitrary library of ebooks.

On stock (and jailbroken) Kindles you can send PDFs or MOBIs to username@kindle.com and have them auto-downloaded to your Kindle. Many people use Calibre[1] (FOSS, win/mac/linux) to sync/manage their ebook collection using this feature. You could easily couple it with Dropbox.

You can also use Calibre to have newspapers/magazines sent to your Kindle every morning. There's tons of recipes for scraping BBC, NYTimes, WaPo or $local_paper, rendering with custom CSS to get readable ad-free version, converting to MOBI and sending to Kindle. There has even been SaaS offerings running hosted Calibre cronjobs with user-provided recipes. Not sure if any still exist.

[1] https://calibre-ebook.com

> On stock (and jailbroken) Kindles you can send PDFs or MOBIs to username@kindle.com and have them auto-downloaded to your Kindle.

That's no good for me because I tend to do a lot of random edits of my epub collection to fix editing errors, replace cover images with better ones, etc. The reason I want Dropbox is to automatically propagate changes like that, not just to transfer files over.

Upstream comment recommends running KOreader on jailbroken Kindle for (amongst other things) syncing with Calibre. I'm assuming this is two-way sync, but I don't know.

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