Know your computer The FACT
It's a ritual across the globe: somewhere between sticking the kettle on and complaining about last night's match, you'll probably hit the button on your ageing company PC and wait while it slowly thinks about turning on. Rather than take it for granted, though, it's worth taking a couple minutes to realize a few of the things that your poor robot slave does without you ever knowing.
Why does that matter? Because on a flash drive, each bit of data is made up of eight separate floating gates, each comprising two physical transistors, which can basically record themselves as either a '1' or a '0'. (Want to be impressed ever further? Each floating gate actually relies on quantum mechanics to work.) That means that an 8GB iPod Touch – the one you were laughing at a minute ago for being puny – has, according to my back-of-the-napkin maths, 549,755,813,888 individual gates arrayed inside that svelte aluminium body. Mighty clever engineering indeed.
1. Bits, Bytes, and Size
Next time you complain about the pitiful memory capacity of your old 8GB iPod Touch, it's worth remember what makes up eight whole gigabytes. Computer science grads will know that in every gigabyte, there's 1024 megabytes; 1024 kilobytes in a megabyte, and 1024 bytes in a kilobyte. Breaking it down to the lowest level, you've got 8 bits in a byte.Why does that matter? Because on a flash drive, each bit of data is made up of eight separate floating gates, each comprising two physical transistors, which can basically record themselves as either a '1' or a '0'. (Want to be impressed ever further? Each floating gate actually relies on quantum mechanics to work.) That means that an 8GB iPod Touch – the one you were laughing at a minute ago for being puny – has, according to my back-of-the-napkin maths, 549,755,813,888 individual gates arrayed inside that svelte aluminium body. Mighty clever engineering indeed.
2. Everything you see or hear on the internet is actually on your computer
All your computer-whizz friends probably delight in telling you how having a 'library' of videos is so 2008, that no-one torrents any more, it's all Netflix and iPlayer and 'The Cloud', whatever that means. But, you might want to remind them: every time you stream a video or the week's latest Top 40 off the web, it's actually, technically playing off your computer.
See, every internet media file has to make a local copy of itself on your machine, first. Ever wondered what that white buffering bar means on YouTube or Netflix? It's the amount of video that's been copied to the local cache, a.k.a. the amount you can still watch if your internet decides to up and die.
By comparison, your body takes around 0.15 of a second for a signal to pass from your fingers, up your spinal cord to the brain, and back down again.
This actually translates up to a neat bit of programming trivia – in the computer science world, all counting (with the rather notable exceptions of Fortran and Visual Basic) starts at zero, not one.
It actually makes a lot more sense – ever thought about why the 20th century refers to the 1900s? It's because when historians decided on the dating system, they weren't clever enough to call the very first century (0-99AD) the 0th century. If they had, we'd probably have far fewer confused school children the world over.
Because of the complicated way a SSD works, over-writing a block of old data with some shiny new data isn't as simple as just writing the new stuff in with a bigger, thicker Sharpie. Rather, the storage drive has to do some complicated shuffling around.
In practice, this can mean that writing a tiny 4KB file can require the drive to read 2MB (that's thousands of times more data that the 4KB file you're trying to write), store that temporarily, erase a whole tonne of blocks, then re-write all the data. It's rather labour-intensive, so think before you juggle your files around next time.
The truth seems to be quite the opposite. One Quora user pointed out that buried within the source code for Java, one of the internet's fundamental bits of code, is this gem:
/**
* This method returns the Nth bit that is set in the bit array. The
* current position is cached in the following 4 variables and will
* help speed up a sequence of next() call in an index iterator. This
* method is a mess, but it is fast and it works, so don't f*ck with it.
*/
private int _pos = Integer.MAX_VALUE;
It just goes to show that even programmers rush things to get home for the next installment of Game of Thrones sometimes.
See, every internet media file has to make a local copy of itself on your machine, first. Ever wondered what that white buffering bar means on YouTube or Netflix? It's the amount of video that's been copied to the local cache, a.k.a. the amount you can still watch if your internet decides to up and die.
3. The distance data travels
A quick experiment for you: click this link, which should take you to Wikipedia. With one click, you've just fetched a bunch of data from servers in Ashburn, Virginia, about 6000km away. Your request has travelled from your computer, through a local Wi-Fi router or a modem, up to a local data centre, from there onwards (under the Atlantic Ocean, if you're in the UK), all the way to Virginia, and back again – in around 0.1 of a second, depending on how good your internet connection is.By comparison, your body takes around 0.15 of a second for a signal to pass from your fingers, up your spinal cord to the brain, and back down again.
4. Counting Starts at Zero
At a base level, every computer's just a really big, complicated calculator. But thanks to the way its intrinsic circuitry works – with lots of little logic gates that are either 'on' or 'off' – every action that takes place at a base level is happening in binary, where things are either a 1 or a 0, with no shades of grey in between.This actually translates up to a neat bit of programming trivia – in the computer science world, all counting (with the rather notable exceptions of Fortran and Visual Basic) starts at zero, not one.
It actually makes a lot more sense – ever thought about why the 20th century refers to the 1900s? It's because when historians decided on the dating system, they weren't clever enough to call the very first century (0-99AD) the 0th century. If they had, we'd probably have far fewer confused school children the world over.
5. The work that goes into a Ctrl+C, Ctrl+V
One rather under-appreciated fact about solid state drives (SSDs), regarded as the gold standard for fast, reliable storage, is the amount of copying they have to do. When you want to copy some data from one bit to another, it's not just a matter of shuffling the data from one part of the drive to another.Because of the complicated way a SSD works, over-writing a block of old data with some shiny new data isn't as simple as just writing the new stuff in with a bigger, thicker Sharpie. Rather, the storage drive has to do some complicated shuffling around.
In practice, this can mean that writing a tiny 4KB file can require the drive to read 2MB (that's thousands of times more data that the 4KB file you're trying to write), store that temporarily, erase a whole tonne of blocks, then re-write all the data. It's rather labour-intensive, so think before you juggle your files around next time.
6. Code isn't as clean as you think
The majority of us put faith in bits of technology you don't quite understand – be it committing your life to a 747, or your dirty pics to Snapchat's auto-delete. When you do you generally tend to assume that the code's been scrupulously examined by teams of caffeine-fuelled programmers, with most of the niggling little bugs found and nixed.The truth seems to be quite the opposite. One Quora user pointed out that buried within the source code for Java, one of the internet's fundamental bits of code, is this gem:
/**
* This method returns the Nth bit that is set in the bit array. The
* current position is cached in the following 4 variables and will
* help speed up a sequence of next() call in an index iterator. This
* method is a mess, but it is fast and it works, so don't f*ck with it.
*/
private int _pos = Integer.MAX_VALUE;
It just goes to show that even programmers rush things to get home for the next installment of Game of Thrones sometimes.
Use Robocopy as a Backup Solution
Just execute robocopy c:\users\tim\documents f:\backup\documents /copyall /e /r:0 /dcopy:t /mir, obviously replacing the source and destination folders with whatever you'd like to backup and where. The robocopy command with these options functions identically to an incremental backup software tool, keeping both locations in sync.
You don't have the robocopy command if you're using Windows XP or earlier. However, you do have the xcopy command, which can be used to do something very similar: xcopy c:\users\tim\documents f:\backup\documents /c /d /e /h /i /k /q /r /s /x /y.
No matter which command you choose to use, just create a script file containing the command and schedule it to run in Task Scheduler and you'll have your own custom made backup solution.
I've chosen to use the robocopy command on my personal computers as my only local backup solution because I like the level of control it gives me. Hopefully you take that as a vote of confidence in this incredibly useful Command Prompt trick.
View Your Computer's Important Network Information
Maybe just for your own information, but certainly when you're troubleshooting a network or Internet problem, you'll probably at some point need to know details about your computer's network connection.
Everything you'd want to know about your network connection is available somewhere in the Control Panel in Windows, but it's much easier to find, and much better organized, in the results from the ipconfig command.
Open Command Prompt and execute ipconfig /all. What displays on screen next is everything important about your network connection: your IP address, hostname, DHCP server, DNS information, and much, much more.
Combine this hack with Command Prompt Trick #7 and you've got a very easy way to get information about your connection to someone helping you with a problem.
Access Previously Used Command with the Arrow Keys
Another great Command Prompt trick has to be the use of the keyboard arrow keys to cycle through previously executed commands. The up and down arrow keys cycle through the commands you've entered and the right arrow automatically enters, character by character, the last command you executed.
This might not sound that interesting, but there are several situations where the arrow keys become huge time savers.
Consider this example: You've typed out 75 characters of a command and then try to execute it, only to find that you forgot to add an option at the very end. No problem, just hit the up arrow and the entire command is automatically entered in the Command Prompt window, ready for you to edit to make it work.
Automatically Complete Commands with Tab Completion
Tab completion is another Command Prompt trick that can save you lots of time, especially if your command has a file or folder name in it that you're not completely sure of.
To use tab completion in the Command Prompt, just enter the command and then the portion of the path that you do know, if at all. Then press the tab key over and over to cycle through all of the available possibilities.
For example, let's say you want to change directories to some folder in the Windows directory but you're not sure what it's named. Type cd c:\windows\ and then press tab until you see the folder you're looking for. The results cycle or you can use Shift+Tab to step through the results in reverse.
Copy & Paste Easier with QuickEdit Mode
How about an even easier way to copy from the Command Prompt? And a secret way to easily paste?
Just right-click on the Command Prompt title bar and select Properties. On the Options tab, in the Edit Options section, check the QuickEdit Mode box and then click OK.
Enabling QuickEdit Mode is like having Mark enabled all the time so selecting text to copy is really easy.
But it also enables an easy way to paste into the Command Prompt: just right click once and whatever is in the clipboard is pasted in the Command Prompt window. Normally, pasting involves right-clicking and selecting Paste.
Watch Star Wars Episode IV
Yes, you read that correctly, you can watch an ASCII version of the full Star Wars Episode IV movie right in the Command Prompt window!
Just open Command Prompt and execute telnet towel.blinkenlights.nl. The movie will start immediately. This isn't a terribly productive use of the Command Prompt, nor is it really a trick of the Command Prompt or any command, but it sure is fun!
Note: The telnet command is not enabled by default in Windows 7 or Windows Vista but can be turned on by enabling Telnet Client from Windows Features in the Programs and Features applet in Control Panel. If you'd rather not enable Telnet but would like to see the movie, you can also watch it in your browser here.
