Showing posts with label Open source. Show all posts
Showing posts with label Open source. Show all posts

Thursday, May 19, 2022

Terra Luna and UST crash, what really happened--Anchor, Luna, UST bankrupted.



* Many people in TerraLuna reddit believe it's an attack. Partly because Luna CEO kept saying 'attack' in revival plan. But if you can at least see below chart, you will understand how withrew UST from Anchor was act of attack. 

Many people thinks that this is stablecoin (or algorithmic stablecoin) problem or crypto coin's problem. Or even call an attack. But if you dig up deeper, it was completely different case--it was Ponzi scheme or even fraud.

They pumped the price of Luna and then converted it to UST--which led to printed more UST than what they really are. People pumped price(for buying Luna), too--I guess. Because Anchor's 20% APY interest rate.


I didn't know much about the Luna and UST crypto coin before. And when the crash was happening, I did some dig up and it took quite some time to understand because it was quite complicated things there--I have to know more about the Luna, UST, stablecoin, algorithmic stablecoin and Anchor protocol.

So I might be wrong about the details but I think my main questioin was right.

I thought about explain what I've learn but things were complicated because it involved with Luna, UST, stablecoin--algorithmic stablecoin and Anchor.

So I will just show you the one chart which I believe I can simplfy main question--where is 10 to 12 billions worth of US dollars(UST)?


That's why LFG(Luna Foundation Guard), Luna and UST were bankrupted--it was just simplification for easy understanding.

Total deposit and borrow on Anchor protocol chart from CoinDesk Rearch, Anchor Protocol Dashboard

Total deposit and borrow on Anchor protocol chart and quoted from The LUNA and UST Crash Explained in 5 Charts @ May 11, 2022 By Sam Kessler, Sage D. Young

About 10 billions of UST was withdrew from the Anchor protocol in 4 days.

As you can see in the chart, people withdrew UST from Anchor. About 10 billions of UST within 4 days which goes to the market to sell their coins.

So much coins were goes to the market which make many people believed that it was an attack.

But I don't think it was the case. Because people deposited Anchor for 20% APY--quite number of people and article said about those 20% APY was not sustainable--you can find artcile like this Anchor Interest Rate, Can They Keep the 19.5% Interest Rate? @ March 14, 2022

Or reddit question like this - Explain like I'm 5: Where does the 20% interest on UST come from?

So if people realised this, they surely withdraw all the UST from there, right?

I think this could be the main reason:

The biggest reason that most people held TerraUSD was because of something called the Anchor Protocol. Think of Anchor as a savings account for your TerraUSD, but it pays you 20% interest — which is a really good deal for a savings account.

In past months, it made sense to simply park TerraUSD in an Anchor account and watch the 20% yield come in, especially because there’s not much you can actually use crypto for. Until as recently as last Saturday, 75% of all the TerraUSD in circulation was deposited in Anchor, according to Coindesk.

But in March this year, Anchor passed a resolution to replace the 20% rate with a variable rate

quoted from Why Did Luna (And The Rest Of Crypto) Crash This Week? @ May 14, 2022 by Richard Nieva, Aman Sethi

How Anchor can pay 20% interest rate?

"Anchor offers market yields of up to 20% on the year." That means Anchor must have enough funds to generate what people desposited here, right?

I don't know the details of thier process--yield interest rate require some time for example, deposit lockup period.

But I will just simplify it.

14 billions UST * 20% APY / 365 days =  about 7,671,232.87 UST/day.

Yield interest takes some time so I will calculate again.


At March 1, 2022, Anchor's deposted UST is about 8.2 billions--below chart.

Total deposit and borrow on Anchor protocol chart - screenshot from Anchor Protocol dashboard

8.258 billions UST * 20% APY / 365 days =  about 4,524,931.50 UST/day.

about 4,524,931.50 UST/day * 30 days = about 135,747,945.20 UST/month.

As you can see, Anchor must have daily income of more than 4.5 millions UST. But they don't have enough income so they try to change the 20% rate to variable rate. But it was way too late.

So you have to ask how Anchor can make that much UST? That means probably Luna Foundation just printed UST without any money(real process is bit more complicated though--minting the UST from burn Luna coin)--which all goes to the open market.

I think I can say that Anchor brankrupted. Or they just printed more UST.

About 10 billions of UST goes to the market for sell.

UST, a so-called algorithmic stablecoin, works with its sister token, LUNA, to maintain a price around $1 using a set of on-chain mint-and-burn mechanics. In theory, these mechanics are supposed to ensure $1 worth of UST can be used to mint $1 of LUNA – which serves as a sort of floating price shock absorber for UST volatility.

quoted from The LUNA and UST Crash Explained in 5 Charts @ May 11, 2022 By Sam Kessler, Sage D. Young

UST called stablecoin but it actually is just artificial stablecoin. So if nobody wants to buy UST, UST can be less than one dollar. As you can read from the quote, Luna will absorbed those difference. But do you think Luna can absorb that 10 billions of dollar? Answer is no. That's why they crashed, right?

Luna Foundation(??) must have more than 14 billions worth of dollars--that's what Anchor's had. But they just have 2 billions worth of BTC in LFG(Luna Foundation Guard) Reserve. You can see the chart below.

CoinDesk Research, Luna Foundation Guard, Blockchair - Luna Foundation Guard Reserve Balance Over Time chart and quoted from The LUNA and UST Crash Explained in 5 Charts @ May 11, 2022 By Sam Kessler, Sage D. Young

screenshot from the CoinDesk Research, Luna Foundation Guard, Blockchair - Luna Foundation Guard Reserve Balance Over Time chart and quoted from The LUNA and UST Crash Explained in 5 Charts @ May 11, 2022 By Sam Kessler, Sage D. Young

But they didn't have that much money. So they--Luna and UST were all brankrupted.



Where those 14 billions of UST coming from? And how Anchor can afford 20% interest rate to pay?

If you try to find out about this question, you will understand why this is Ponzi scheme and fraud.

You probably have other question like this: How this 3 to 10 billions of UST came from in first place? Which will lead to quite complicated matter because it involved Luna and UST and how it works. I don't think I can explain all here because article will became too long so I will talk about it later.

Or you can read it article like this:

 - Stablecoins, explained: Why the crash of Terra and Luna has investors on edge - CNN @ May 13, 2022
 - The LUNA and UST Crash Explained in 5 Charts @ May 11, 2022
 - Why Did Luna (And The Rest Of Crypto) Crash This Week? @ May 14, 2022
 - Anchor Interest Rate, Can They Keep the 19.5% Interest Rate? @ March 14, 2022



P.S. People in reddit still saying it was an attack. So I wrote post like this - How withdrew UST from Anchor can be an attack? Anchor and UST was like--bankrupted.

Hopefully, more people understand the problem.


Thursday, February 10, 2022

Safari wasn't competitive enough. Because not open platform. -Open source is the future.


I've seen this tweet:


 I don't know much about the issue because I don't use Safari. But what I don't understand is 'fix the problem' or 'solve the problem' wasn't the fundamental issue, I thought. For example, design flaw or missing function was not the bug, right?


So I wrote about in twitter and below writing is almost same as my tweet.

I don't know much about Safari, now. But what I know is nowadays without open platform, you won't be competitive enough.

I googled about market share and I was surprised because Safari does quite good--19.84% source from Firefox only 4.18%. Chrome 63.03%.
So I thought I was wrong about what I wrote.

Web browser market share wordwide by all platform. at February 10, 2022


But that's all platform which means smartphone's web browser marketshare included.

So desktop marketshare will show I wasn't wrong.

Web browser market share wordwide by desktop. at February 10, 2022


Safari 9.85% but Firefox also similar like 9.16%. And that's not end there because Edge 9.53% which Microsoft decided to become open source. And chrome wasn't exactly open source but chromium is. So can call open platform.

I didn't google about the Safari but I remember when I was using Safari in Windows several years ago. And I never heard after that.

And Chrome and Firefox all support multiple platform. But I don't think Safari does.


screenshot of 'Safari version history - Wikipedia' src:wikipedia at February 10, 2022


And when I try to make wallet for some cryptocurrency. Many were support web browser app which call the web browser extension or addon. So I can conviniently use cryptowallet.

Oh, sure, many crypto probably have iOS and android app.

But I don't think I have seen any web browser extension app for Safari. Mostly Chrome and Firefox. Sometimes, Edge, too.


So I'm quite sure that I can say Safari('s closed platform) can't catch up with open platform like Chrome, Firefox and even Microsoft's Edge.

Here is the what I wrote in the tweets:

You can read more about it--Open source is the future. I will talk more about it--later. @ February 7, 2020


Friday, February 7, 2020

Open source is the future. I will talk more about it--later.

I thought about writing this about a year(or less) ago. And I think I did write a few pieces about it but I wasn't able to find it--I have so many text file on my hard disk drive so I didn't have enough time to check out everything.
So I will write a piece first.

You can click here to what I talked about 'open source' in my twitter.

Long ago, Microsoft as evil empire or something.

Not so long ago--or a few or a decades ago, people called Microsoft as evil empire so when people mention about the MS(Microsoft), they wrote as 'M$' or something.
When I saw that 'M$', I thought that's how abbreviation works--or slang in English. At the time, I haven't learn English so I might slightly messed up my memories.

But time has changed.

screenshot @ 1:50p.m. February 7, 2020: Number of Linux distros on Microsoft Store
You can find number of Linux in Windows 10's Microsoft Store like photo above. One of the most famous open source project is Linux. And Windows 10 support it.

So I think I can say Windows 10 started to support Linux (kind of...) natively.

screenshot @ February 7, 2020: Windows Subsystem for Linux in Windows 10's Windows features.
You probably need update Windows 10 to see the Windows Subsystem for Linux from Windows features like photo above.

Microsoft shipped full Linux kernel about last May which I tweeted about it:

It was still development stage, I think.

And that's not all.

If you are using Android smartphone, you can go to find bunch of free Microsoft apps in Google's play store. Android is open source and Microsoft made a lots of apps for it.
And number of Microsoft's Windows application like calculator made it to the open source. is software development platform. And I think it is very famous website for the 'open source software project'.
And you can find so many github project from Microsoft--you can click here to see it yourself.

I just found Microsoft has open source project website

See. I am quite sure that I can say 'time has changed'.

* I will talk more about it later. I don't know when can I write more but hopefully soon.

Monday, May 27, 2019

Huawei price shock? Where can I buy that $130 P30 Pro you mentioned?

Here is the article - Huawei Price Shock: Value Of Flagship $1150 P30 Pro Comes Crashing Down To $130 @ May 26, 2019
saying that it values $130. Because of Huawei ban.

On the same site, the Huawei P30 Pro, also in good condition, will now return just £100, less than $130. It has lost almost 90% of its value.

"Trade-in prices for the P20 Pro are now as low as £50," which quoted from U.K.'s Express newspaper--P20 Pro SHOCK as Huawei fans suffer most devastating news yet | @ May 25, 2019
Quoted from Huawei Price Shock: Value Of Flagship $1150 P30 Pro Comes Crashing Down To $130 @ May 26, 2019

This newspaper screenshot the trade-in values from MusicMagpie websites.

But as you can see from the photo, they were selling refurbished Huawei P20 Pro for £314.99 to £459.99.
So they can make £300 to £400 from cleaning the phone? Is this what people call it as "rip-off"?

Huawei price shock? Where can I buy that $130 P30 Pro or  £50 P20 Pro you mentioned?

If you can't see clearly, you can use this link--google photo link.

Trade-in company don't want to risk--because of Huawei ban. Sure, price will drop because of update issue.
But it doesn't mean secondhand price drop like £50. See above--in the photo. Even sell £350 but buy £50?
Huawei P30 Pro return just £100, less than $130??

Do some research--you don't even need to be in UK to find out--> Just google with "second hand p20 pro in uk".

If price drop like that, people will buy it form there and sell to other country--that's why a lot of people carry iPhone to sell other country--several years ago.

If I can buy P30 Pro for $130, I will surely buy it --3 or 5 of them. And P20 Pro for £50, I will go to buy 3 or 5 of them.
And if I can't sell it in my country(because almost nobody use Huawei phone), that's okay. Because I can give to all my family and friends.

* Many times, won't sell many Huawei smartphone--or Xiaomi smartphone. I know this because I did try to buy it from there. I think reason is not many people (in the USA), using Chinese smartphone. So I don't think it will impact rest of the world--I mean secondhand price of Huawei smartphone.

* Here is the list of link that I use in the photo:

Saturday, March 16, 2019

Can Raspberry Pi boot from USB flash drive? And about how to do it guide.

Simple answer is 'yes, it can' but read on....
Or skip to the "So I will write summary first:" below.
Or skip to the "Raspberry Pi 3 B+ support USB boot.  How about Pi Zero W? Or other Pi?" below.

Not everyone is beginner, I think.

When people looking for how to guide for installing the OS(operating system), they were probably beginner or very first time trying to use Raspberry Pi. If that's the case, step by step guide might be very good choice.

But even so, it is better to explain general concept, I think.

If someone already knew some computer stuff, he or she probably doesn't need that step by step guide. Because Raspberry Pi is computer that means it is same concept.
For example, someone is Windows user like me and some Windows user knew if computer--motherboard support USB booting, Windows user can simply go to the CMOS setting and do boot from the USB stick.
So I'm thinking Raspberry Pi is computer so it might support USB boot, too.

So I'd like to know whether Raspberry Pi support USB boot or not. Or I might have to do something to get USB boot.
That's what I want to know, right?

So I will write summary first:

BCM2837-based Raspberry Pis which were all the Pi 3 models include compute module 3 and Pi 2 Model B v1.2, support USB host and Ethernet boot.

So if you have any of models with BCM2837, you can follow any general install OS guide (and install to the USB flash memory stick) which you might already knew.

And if you have other models include Pi Zero and Zero W, you need single file on your micro sd card and then it will boot from USB memory stick. So you can boot from USB memory stick and also need micro sd card with single file which I will explain below.

thought about boot from SD and then USB.

I am currently using the multiboot via berryboot.

And sometimes, I felt berryboot wasn't enough what I am trying to do. So I am thinking about like that.
3 or 4 OS on SD card and then 1 or 2 OS from USB flash memory.

So I was googling about it like this:
how do i install raspbian on usb memory

And I clicked below guide:

And read this part:
Important information
This tutorial is out-dated and has been updated here: ....
So I did clicked link which is below guide:

I have a Linux machine but most of my data--Raspberry Pi image file and etc, was on Windows which is my main computer.
So I clicked Windows version tutorial--below link.

I appreciate the detail guides. But when I am trying go through this guide it made me very confusing.
See this "Step 2 – Install Raspbian to the micro sd card"
And then "Note: If you’re using a Raspberry Pi 3+, you don’t need to do step 2. Jump straight to step 3."

"Step 3 – Install Raspbian to the USB Flash Drive"
The process is exactly the same as step 2, but this time we choose the USB flash drive as.....

And here--"If you're using a Raspberry Pi 3 Model B+, you can skip step 4."

"Step 4 – Prepare the Raspberry Pi for boot from USB"

"Step 5 – Boot Raspbian from USB Flash Drive"

I realised that it is exactly same step as install Raspbian on micro sd card.

I have Raspberry Pi 3 B+ and Pi Zero W. So I already knew how to installing any OS on micro sd card.

As you can see, it took very long time to figure out.
Unfortunately, I clicked very old guide--May 2013. That probably is the reason though.

Raspberry Pi 3 B+ support USB boot. How about Pi Zero W? Or other Pi?

I am thinking newer Pi can support boot from USB memory stick but how about Raspberry Pi Zero W which I also have.

So I googling about it and found this:

This question already reveal how to do the booting from USB stick.

Quoted from the question.
The older Raspberry Pi's (Pi 1, Pi 2 and Pi Zero) couldn't boot from a USB-device, but the Raspberry Pi 3 has support for it. The Pi and Pi 2 have semi-support for it (using an SD-card with a single bootfile).

So if I wanted to boot from USB stick in Pi 1 and 2, I can place single bootfile--which I don't know it yet.

And other people answered that Pi Zero W use older chip like Pi 1 and 2.

And then I found someone wrote about that single bootfile--bootcode.bin.
And pointed to the source:
Special bootcode.bin-only boot mode section in Raspberry Pi boot modes - raspberrypi/documentation
Quoted from above link:
USB host and Ethernet boot can be performed by BCM2837-based Raspberry Pis (these are all Pi 3 models, and some Pi 2Bs). In addition, all Raspberry Pi models can use a new bootcode.bin-only method to enable USB host and Ethernet booting.

Just format an SD card as FAT32 and copy on the latest bootcode.bin.

This is useful for the Raspberry Pi 1, 2, and Zero models, which are based on the BCM2835 and BCM2836 devices, and in situations where a Pi 3 fails to boot (the latest bootcode.bin includes additional bugfixes for the Pi 3, compared to the boot code burned into the BCM2837).

If you have a problem with a mass storage device still not working even with this bootcode.bin, then please add a new file 'timeout' to the SD card. This should extend the time it waits for the mass storage device to initialise to six seconds.

I'm not 100% for sure yet. But if Raspberry Pi use BCM2837, USB host and Ethernet boot will support.

And I found all the Raspberry Pi specifications from Raspberry Pi - Wikipedia.
Screenshot of Wikipedia's Raspberry Pi Specifications section.
And as you can see, Pi 2 Model B v1.2 uses BCM2837. And all the Pi 3--3 Model A+, 3 Model B, B+ and Compute Model 3, lite, 3+.

So if you have Pi 2 Model B with v1.2, Pi 3 series and Compute Model 3 series, you can just install any OS on USB stick and remove micro SD card.

If you have other version include Pi Zero W, you can format the micro SD card and copy the bootcode.bin file.

Yes, I haven't tried it yet. But I think those are from the Raspberry Pi's official repository.
So I'm sure it will work.

Kali and Raspbian booted from USB flash drive.

I probably have to get more information about it so I just found this:
quoted from above link:
HawaiianPi wrote:
The Pi3 will check for a boot SD card first, before booting from a USB device. If no boot SD card is found in 5 seconds, then it looks for a boot USB device.

I think this is quite similar process as USB boot in PC--desktop and laptop computer.

When I read from above link, someone said some USB disk won't work. And I wasn't sure about it--If it's FAT32, why it shouldn't be.

But first I tried with quite old 8GB USB stick, it didn't work--Pi 3 B+ without micro SD card and Pi Zero W with single file on micro SD card.
So I thought I need to do something.

And I realised this could be compatibility issue. So I put my kind of new memory card read which can read SDXC format card, too.


As you can see that micro sd card slot is empty.
Kali lite booted from USB Flash memory stick in Raspberry Pi 3 B+.
That USB memory stick doesn't work with USB boot--I tried like 2+ os and also with Pi Zero W.

This time, I tried same USB memory card reader with Pi Zero W. And it worked well.
And I had to put single file in micro sd card.
Raspbian stretch booted from USB Flash memory stick in Raspberry Pi Zero W.

If you'd like to connect more than two USB stick, portable hard disk or SSD, things became quite complicated. Because Raspberry Pi doesn't know which USB drive to boot from.

So you have to search more about it.

I hope you did learn about the basic concept or process of USB boot in Raspberry Pi.

Friday, March 15, 2019

Adafruit's Portable 5 inch Monitor with HDMI DIY looked interesting. But in reality....

I've seen this video: Portable HDMI Display for Raspberry Pi - YouTube

And I thought it looks very nice and quite useful because it isn't only for the Raspberry Pi--I can use as my DSLR monitor or game console monitor as well--I have a Nintendo NES classic edition which is kind of portable console.
So I'd like to do this....

It's expensive than I expected.

But when I saw inside of it, it shouldn't be easy to do.
Building the portable monitor won't be easy, for sure--I haven't done soldering before. But it requires a lot of parts to buy, too.

And if I do this, I might learn a lot of things about Adafruit, for sure.

So I visited building guide wep page.
Overview | Portable 5in Monitor with HDMI | Adafruit Learning System

And I realised I don't only spend a lot of time, I need a lot of money to building it, too.

  • 5.0" 800x480 TFT Display $29.95
  • TFP401 HDMI Breakout $24.95
  • FPC Extension Board $4.50
  • Powerboost 1000C $19.95
  • 2500mAh Battery $14.95
  • Slide Switch $0.95
  • Tripod Screw Insert $1.50
  • Total: $96.75

I thought this is too expensive for me. I need other things like print 3D case and lots of tools to do this.

So when I go through their guide, I saw that it can powering up the screen through USB.
That means, I can simply use my smartphone powerbank.
So no need to buy Powerboost 1000C and 2500mAh Battery.
And I don't have 3D printer so I don't need slide switch and tripod screw insert, too.

So I need three parts--5 inch display, TFP401 HDMI breakout, FPC extension board.
So total $59.4.

Cheaper or even better alternative--Aliexpress.

That means I don't need to do this.
Because I can simply buy from cheap Chinese store in Aliexpress, like this:
This is screenshot of 5 inch capacitive lcd display from Livetime Store in Aliexpress.
5 inch Raspberry Pi 3 Model B+ Touch Screen 800*480 Capacitive LCD Display + HDMI Cable + USB Cable + CD for Raspberry Pi 3-in Demo Board Accessories on

This is 5 inch capacitive touch display. And it costs $38--include free international shipping.
This model was different driver board design than 5 inch resistive display so I couldn't find case for this model.
5 inch resistive display case costs $6 to $10 in Aliexpress.
I can buy 5 inch display with case for about $48.

So it's much cheaper and better(include touch panel) than Adafruit's.
I know this because I just ordered one from there. So I search the a lot of similar--5 inch lcd.

If I wanted to learn about Adafruit, I probably can invest that much time and money.
But now I'd like to more focus on Raspberry Pi--and programming.

So I will buy 5 inch capacitive touch display.

You can also buy other 5 inch screen from Aliexpress like this:

This is the screenshot of '5 inch lcd hdmi' search result in Aliexpress.
Buy 5 inch lcd hdmi and get free shipping on

This is the screenshot of '5 inch screen' search result in Aliexpress.
Buy 5 inch display and get free shipping on

When you are searching the lcd screen, it doesn't show up many items. But you can find store that specialize in Raspberry Pi or SBC(single board computer). So you probably have to check Raspberry Pi store one by one.

It looks hard to build but maybe not that much.

At first, I don't think it's easy thing to do. When I saw this link:
On/Off Switch | Portable 5in Monitor with HDMI | Adafruit Learning System
It doesn't seem to easy, does it?
But if you are thinking about portable project, I think it's worth the effort.

I saw the next page. And if I learn about soldering, I think I can do this.
TFP401 Driver | Portable 5in Monitor with HDMI | Adafruit Learning System

And next,
Display | Portable 5in Monitor with HDMI | Adafruit Learning System
This part need just connect and position the cable. After that, screen is working.

Next part is mounting to the case.

Overall, if I learn and practicing soldering, it shouldn't be so hard.

But I still don't have a 3D printer and I don't like spend that much money.
So I will buy from Aliexpress.

Many of web store like adafruit, elements14, sparkfun, pimoroni were probably based on USA or UK so shipping and currency is too expensive to my country--Korea.
And same kind of store in Korea was all imported from those countries so things were much more expensive.

That's why Aliexpress is the best choice--for me. And probably to you, too.

Saturday, September 16, 2017

Capitalism won't dominate this world.... Yet.

I haven't listen the audiobook for quite long time so I've visited LibriVox website--public domain books that people recorded.

And I found this book - The Mysteries of Paris - Volume 1 by Eugène SUE.

When I listen the chapter one, I was very and very intrigued by her lovely voice--Cori Samuel. And I found her website--To Posterity — and Beyond!.

I read a few things from there and I click the Voice services.

She said
At the moment, and for the foreseeable future, I am not accepting commercial recording requests.
Because she was so enjoy recording works for the public domain.

It's not everything is about money--commercialised.

People are so much focused on the making the money--That's how and why capitalism issue came from. Unfortunately, not many people see this side of the world--open source, public domain, wikipedia, creative commons, etc.
You can find so many websites or organisations doing those.

If you can see this side of world, you can see that we, human being's future is still bright.
We just need more people to involve and promote this open(and sharing) culture.

Wednesday, May 25, 2016

Nexus 7 2013 Marshmallow, won't allow to install app--apk file.

If you are looking for solution in forums, they will probably ask 'why you need install app without Google play store' or 'are you trying to install cracked app--illegally unlocked copyright version app'.

I tell you why I need this.
I bought secondhand Nexus 7 2013 (second generation) tablet for my sister so I don't want to do all the things like google log-in process and wasting my limited internet resources (I don't have unlimited internet access.) for downloading apps and sync the app data,
for just testing the tablet.

I just wanted to install some apps like movie play app, photo viewer app, music player app, camera app and some 3d-ish game app or copy some video file so I can check whether this secondhand tablet will work properly or not.

So I just need to install two to four apps to testing the tablet.

Here is the tablet's version info:
Nexus 7 and Android 6.0.1
Screenshot of Settings -> About tablet in Nexus 7

check 'Unknown Sources' in settings for install apk files

If you searched web for 'how to install app (apk file) in Nexus 7', you will find solution like this
Settings -> Security -> turn on 'Unknown sources'
Screenshot of Settings -> Security in Nexus 7

but this doesn't work. Because tablet still don't allow to installing the app.

Screenshot of Settings -> Storage -> Internal Storage
Screenshot of Settings -> Storage in Nexus 7

'Explore' to install the apk file.
But you will get message like this:
'Cannot open file'.
When you trying to install the apk file, you will get error message like this.

How to transfer apk file in Nexus 7.

Many of Android smartphone and tablet probably will have MicroSD memory card slot so most cases you can copy files easily. And not only that.
They will probably have USB-OTG function which you can simply put the usb memory card to the smartphone or tablet via USB-OTG cable.

But Nexus 7 don't have memory card slot. So what you can do is send file via bluetooth or NFC. Or use internet or connect PC with usb cable.

But it looked like apk file won't allow to do transfer via bluetooth or NFC. So you can do it via internet or connect PC with usb cable.

So I use send-anywhere websites to transfer apk file:
trying to send file via

and then use download app to install apk file but I've got same error 'Cannot open file'.
'Downloads' app to install apk file but same error - can't open file

I can transfer to the apk file but can't install it.

Only way to install the app is use android app development tool ADB.

I already install the Android Development Tool on my PC and this article became quite long so I will not explain how to get and use the tool.

You can follow one of these articles:

You don't need install whole Android Development Tool to get ADB file. You can find only ADB file and Android USB Driver for Windows(or possibly your system already have it).

You need to turn on 'USB debugging' option in 'Developer Options'. That means it must turn on 'Developer Options' via clicking 7 times in Settings -> About tablet -> Build Number.
* detail guide is here How to enable developer settings on Android 4.2 | Android Central

Connect tablet to PC and then Window+R to type 'cmd' to enter 'Command Prompt' console mode.
install apk file in Nexus 7 via ADB tools - Windows

Make things easier, copy the apk file in the same directory as ADB file is in, and change apk filename short like this because Windows Command Prompt won't easy to handle long filename.
For example here is 'adb install es.apk'.

Finally, install the apk file via ADB from PC.

So install the File Explorer app like ES File Explorer should be better choice. Because this app will allow to install apk file like this:

install app from ES File Explorer in Nexus 7

install app from ES File Explorer in Nexus 7

installed app from ES File Explorer in Nexus 7

If you need more detail guide about use ADB, you can do similar like this: [GUIDE] How to install APK Files on your Nexus Player | xda-developers forum
This guide is for Nexus Player but most of Android smartphone and tablets were all the same.

P.S. I'm quite confusing because I did this(install apk files) many times with variety of Android smartphone and tablet. Most of times, I just sent apk file via bluetooth and installed easily with turn on 'Unknown sources'.
So this is probably Marshmallow problem. Or Google probably blocked 'Unknown sources' option.

Tuesday, May 24, 2016

How to switch or select OS(operating system) in Teclast X98 dual boot tablet.

I bought secondhand Teclast X98 Air ii and I couldn't find any way to enter Windows OS(operating system).

So I googled it and I found that

to enter OS selection screen in Teclast dual boot tablet.
'Volume Up' button + 'Power' button will enter the OS selection screen.

How to switch or select OS(Operating System) in Teclast dual boot tablet.

Easy way to do this is first press 'volume up' button and then press 'Power' button.

How about other dual boot tablet?

Many other tablets like Chuwi, Cube has dedicated Windows application and Android system app so you can use this application or app to change to desired OS.

And Teclast X98 Air 3G also had this app. But Teclast X98 Air ii doesn't have this app--maybe there has but my tablet doesn't have.

If you have Teclast X98 Air 3G and would like to install os-switch app, you can check this link:

Details about OS selection process in Teclast dual boot tablet.

When you enter the OS selection screen,
Teclast X98 Air ii - OS selection (Android, Windows) screen

you can either choose from top left corner check-box:
  • boot up OS without OS selection screen
  • or boot up OS with OS selection screen in 10 seconds.

Teclast X98 Air ii dualboot tablet- OS selection (Android, Windows) screen explained

So if you remove that tick in check-box, you won't see this OS selection screen. So if you need to change OS, you have to Volume Up and Power button together to see this screen.

And choose whatever OS (Android or Windows) you desire, and touch 'choose OS' button.

When you changed OS, you will see message like this:
Teclast X98 Air ii - when the os selection was changed.

Thursday, May 19, 2016

Teclast X98 Air ii, dual boot tablet - how to change memory size for android.

Is it possible without reinstalling the system?

Answer looks like 'no' at the moment.

I am trying to reduce the Android memory size and increase the Windows hard disk size.
What I have found so far, I can delete whole Android system or delete whole Windows system.
It looks like quite hard(or impossible) to reduce the Android size because Android uses 7+ partition which you can see the below photo.

So it should better to install one by one--Windows 8.1 and then Android. Or vice versa. During installation, I think it can allocate partition size--I haven't found out yet so it was just my guessing.

First, how much space on the 64GB hard drive is assigned to Android and Windows?

I bought secondhand x98 air ii 64gb so I'm not sure about whether it is factory setup or not.
But mine was 39gb(include 5gb for windows recovery) for Windows and other remains--22gb(it seems) for Android.

Here is partition allocation table from Windows' disk management.
Teclast X98 Air ii 64gb - default partition allocation - Windows 8.1's disk management

Here is Android's memory size from storage menu in settings.
Teclast X98 Air ii 64gb - default Android memory size - Storage menu in Settings.

Second, what is the optimal partition size for Android and Windows?

I think there hasn't any optimal partition size because it's all depend on usage.
I don't like installing so many apps on Android and Windows. So in my case, 8gb is surely enough for my Android--I have a 16gb android tablet and half was empty so I can manage with that size. And I can put data(ebooks, songs, videos, etc) on micro-sd memory.
And I don't need big memory on Windows but sometimes, some software need big size--mostly games, so I'd like to have more space on Windows.

I'm thinking about upgrade to Android 5.0 from 4.4.4. So during that process, I hope to reduce the partition size.

This is one guide that delete Android and then those Android's memory allocate to Windows so without reinstalling the os--operating system.

* Koko Pudja's guide: How to delete Android and merge partitions in Windows for more space
Same tutorial but with photos to help much easy to follow.

I think this guide is apply to all the dual boot tablet such as Chuwi, Teclast, (Onda, Cube?) which had two operating system, Windows and Android.

Tuesday, November 25, 2014

This is why Wikidpad has so much potential in it.

WikidPad - wiki notebook for Windows/Linux/Mac OS

wikidPad is a Wiki-like notebook for storing your thoughts, ideas, todo lists, contacts, or anything else you can think of to write down.

What makes wikidPad different from other notepad applications is the ease with which you can cross-link your information. Links in a wiki are created by typing in WikiWords.

Donationcoder forum's user CWuestefeld explained about Wikidpad @ January 31, 2008

I would suggest to read from the link.

These are the quotes from CWuestefeld:
"... its parent. But a wiki allows any node (page) that relates to another to offer a link to it, leading eventually to a very densely packed structure."

"if you're consistent about the way you name things in a wiki, you'll find that the interconnectedness arises all on its own. You don't need to intentionally create a link; the link manifests itself based on the usage of similar terms."

"It's very gratifying when working in a wiki to discover that you've already done something that you forgot about. As you're describing a related concept leading up to another page, you find that the link is already populated; simply by thinking descriptively and consistently, you've created a knowledge web that not only holds together, but reinforces itself."

When I read about it, I also understand why wikipedia made whole different internet-era.

It's an idea that matters most. Isn't it?

Tuesday, November 5, 2013

Unfortunate happen in human society…farewell to the

Unfortunate happen in human society. So I should say #farewell to the #isoHunt. (this link is wikipedia article of isoHunt) #p2pSearchEngine #BitTorrent

Why? Because Knowledge became more powerful than ever in digital age which develop more and more society divided issues. #moneymakesmoney

These lawsuit will bring down these things and poor people will never get chance to improve themselves. Who cares about poor people, right?

Tuesday, October 15, 2013

Possibilities of revert to old Nokia.

It's pointless to saying these kind of things now. But I will just write it for record. So I will just write some steps only, not details.

Let people make aware of Nokia was back.

Workers in the company sue Board-of-directors and Stephen Elop and others who intentionally plan to sell Nokia (with bargain price, more specifically a penny).

Workers didn't plan to join Microsoft, they were joined for Nokia which means include Symbian.

Actually, it wasn't important step but this can make people to aware about the Nokia.

Other stunt which related to next step, is Nokia should trying to buy HTC.

I will explain why.

Nokia should make Symbian handset. But not only that.

Nokia should make devices for Symbian and Meego again. And Android, too.

But that's not all. Even make Windows phone. Why not?

HTC doing that. Samsung doing that. LG doing that. So why not?

And Symbian and Meego is open source and open platform(I know there has some issues but still..) and Android is open source and open platform.

So what's the problem with make all the open platform, right?

And one good thing is that Stephen Elop made Nokia to OEM Nokia manufacturer–This is why Microsoft can buy Nokia for a penny. You can read details here: Conspiracy is just conspiracy. Are you sure? @ September 6, 2019

So Nokia has really advantage for this step.

Nokia already became OEM manufacturer so why not buy other similar company like HTC, right?

And if Nokia tries to buy HTC, people will aware that Nokia is back.

Of course, meanwhile Nokia should support Symbian and Meego to grow.

Symbian and Meego are open platform so they should open for other handset maker.

Symbian did that last time but Nokia was dominated whole Symbian market so Symbian doesn't need other handset maker.

Now it changed everything. So this is the time that Symbian and Meego can go their own and open the platform to all the handset maker.

Whether you believe it or not. Symbian(and Meego) still has their own strength.

I wrote this article about three years ago. And I've played with newer version of Android.

And it reminds me that I can't use Android phone as my primary phone after two years of upgraded Android OS. Because what I've mention in the article.

My phone is Nokia N8 and I didn't upgrad it to Belle which is newer version OS because I am satisfying with not-so-newer-OS.

You can read it here: Nokia could do far better with their customer. (Part 1 of ..) @ February 12, 2011

This is a good thing to customers, too. Because people can have variety of choices for open platform.

Diversity is a good thing in human society. That's what I believe.

I know…

there has so many issues and it's too late.

I can see Android platform has huge potential but interesting thing is Symbian and Meego, too.

Because I believe majority of people can't be a geek. And even if it did, it doesn't matter because people don't want to wasting time playing with the phone.

P.S. Nokia released Android phone with Lumia 520 hardware.

The new Nokia X family – Your Fastlane to Android™ apps

This is Nokia X: Android and Windows Phone collide By Tom Warren on February 24, 2014
- wrote at February 24, 2014 at 8:44 pm

Wednesday, September 25, 2013

Why Google Chromebook doesn't much attract?

I am using the catch website which can keep personal memos and notes. Mostly, I am using this app from Android phone.

And I just thought that this app might have Chrome browser's app so I can make notes without internet connection, I thought.

This is a screen shot of catch app in Google Chrome's webstore.

What this app does is just open the website of catch. Nothing more.

So this is an app or just a bookmark?

I know some people might need bookmark as app but if Chromebook can't use with internet connection, how can you sell the product to the country with not-so-good internet connection and people who living in outside city-I don't think most country has very good internet infrastructure in countryside.

Oh, I forgot to mention that not only catch app did this.

I have seen a number of apps did this, too. And even google apps.

Anyway, that's why I wrote review with this comment:
Nowadays, bookmark became app. How clever!

Wednesday, June 5, 2013

This is the reason internet is the future and it will bring equality to human society.

Public domain, open source project, creative commons, etc. These kind of things I will talk about here, too.

That's what I believe.

Here May Clipart Be Used Comparison – Openclipart

Their cliparts which were made by people who believe in public domain, are all freely use.

You can read further from here

Thursday, April 14, 2011

This is the reason why I liked Nokia but….

Symbian is open platform and Nokia always trying to help local community especially developing countries. And there has so many other reason that why I like Nokia.

For example, Nokia cares about environment like this Putting a ban on conflict metals @ August 26, 2010 by Saara and was supporting this kind of event Conspiracy For Good.

But Nokia gave up the Symbian platform.

But Nokia threw away the Symbian platform. And it seems to me that Nokia strategic changed to go after money only. It calls 'profit'.

So I was not interested in Nokia phone anymore.

It's time to move on.

So I have to choose other platform from WebOS, Android or Meego because I am not interested in closed platform like iPhone or Window Phone 7.

What choice do I have? I thought about go for Meego (or WebOS) platform but it wasn't ready yet. So I choose other open platform-Android.

So I have bought Milestone smartphone and Enspert's Identity Tab E201 which was Android tablet.

So I'll probably talk about the Android vs. Symbian later on.

Friday, October 15, 2010

Rome was just made up within one day?

It was an issue so I thought about to write at my tumblr What really Nokia need.
But this post's main theme was important for this blog, too. So I will write it here.

Image via Wikipedia

There have too many speculation about MeeGo. Why?

MeeGo was merge project from Nokia's Maemo project and Intel's Moblin project. I know it was already progress a lots but it still need a lot of time.
And open source project can't just get good result like FireFox project or OpenOffice project within one year. It will take much of time.

I found that OpenOffice project was starting around July 2000 which Sun's StarOffice source code was released. So how long does it take to the commercial stage?

MeeGo was starting around in this February or later. MeeGo's welcome post was Welcome to MeeGo @ February 15, 2010 by Imad.
So it was just 6 or 7 month in development and people are crying and crying (especially who?) about Nokia wasn't release the MeeGo device.

So this very reason Nokia will not officially support MeeGo to N900 because commercial device can't support to "Beta stage's operating system". It's that simple.

MeeGo's official blog was posted this: MeeGo calling – on N900 @ October 13, 2010 by Harri Hakulinen.
I haven't read whole thing but I noticed that MeeGo was open source project so if many people join and want to do something, MeeGo will support it. Because that's what open source is all about.
But I don't think people notice about it. That's why some people thought that MeeGo official blog says MeeGo will support N900 which means Nokia must support officially N900 on MeeGo.

So some people asked to Nokia whether Nokia N900 will support MeeGo.

Here is what I've got tweet from @thenokiablog
UPDATED: Nokia N900 dual boot will not be an option to consumers
about 20 hours ago via Echofon

That tweet's link is this: Nokia N900 PR 1.3 Update Coming Soon With Dual Boot to Meego @ October 13, 2010 by Mark Guim

Don't confuse about this, please.

I am not saying it was people's fault. I am saying Nokia didn't properly telling to the people about MeeGo. That's what this all kind of rubbish speculation was came out.

What if Nokia was telling people like this "commercial product can't sell with Beta Stage of Operating System like MeeGo" and other things like "open source project usually takes a time for out of beta stage".
Don't you think people will understand better?