Freeze ! I´ll save your state.

When you click on the "Close" button of your virtual machine window (at the top right of the window, just like you would close any other window on your system), VirtualBox asks you whether you want to "save" or "power off" the VM. (As a shortcut, you can also press the Host key together with "Q".)

The difference between these three options is crucial. They mean:

• Save the machine state: With this option, VirtualBox "freezes" the virtual machine by completely saving its state to your local disk. When you start the VM again later, you will find that the VM continues exactly where it was left off. All your programs will still be open, and your computer resumes operation. Saving the state of a virtual machine is thus in some ways similar to suspending a laptop computer (e.g. by closing its lid).
• Send the shutdown signal. This will send an ACPI shutdown signal to the virtual machine, which has the same effect as if you had pressed the power button on a real computer. So long as the VM is running a fairly modern operating system, this should trigger a proper shutdown mechanism from within the VM.
• Power off the machine: With this option, VirtualBox also stops running the virtual machine, but without saving its state.

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Blogging safety guidelines

This post article is intended to students about to open their blogs to the web and student´s parents. Blogging is a thrilling activity, many enthusiast and professional bloggers describe the experience as "life changing". For that experience to be safe, there are a number of considerations you should know about, which I´ll share with you in this post. The following content is a compilation from a variety of sources, such as experts web sites, government regulations and some schools disclaimers.

Eight safety tips for blogging (English). Download.

(Post under construction)

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Create your first VM

See the following two screencasts to learn how to create a simple VM.

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Introduction to VMs

The techniques and features that VirtualBox provides are useful for several scenarios:

Running multiple operating systems simultaneously. VirtualBox allows you to run more than one operating system at a time. This way, you can run software written for one operating system on another (for example, Windows software on Linux or a Mac) without having to reboot to use it.

Easier software installations. Software vendors can use virtual machines to ship entire software configurations. For example, installing a complete mail server solution on a real machine can be a tedious task. With VirtualBox, such a complex setup (then often called an "appliance") can be packed into a virtual machine.


Testing and disaster recovery. Once installed, a virtual machine and its virtual hard disks can be considered a "container" that can be arbitrarily frozen, woken up, copied, backed up, and transported between hosts.

Snapshots and saved machine states. On top of that, with the use of another VirtualBox feature called "snapshots", one can save a particular state of a virtual machine and revert back to that state, if necessary. This way, one can freely experiment with a computing environment. If something goes wrong (e.g. after installing misbehaving software or infecting the guest with a virus), one can easily switch back to a previous snapshot and avoid the need of frequent backups and restores.

Infrastructure consolidation. Virtualization can significantly reduce hardware and electricity costs. Most of the time, computers today only use a fraction of their potential power and run with low average system loads. A lot of hardware resources as well as electricity is thereby wasted. So, instead of running many such physical computers that are only partially used, one can pack many virtual machines onto a few powerful hosts and balance the loads between them.

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Scratch project nro. 1

Lets create a maze ! Numerous mazes of different kinds have been drawn, painted, published in books and periodicals, used in advertising, in software, and sold as art.

A maze is a tour puzzle in the form of a complex branching passage through which the solver must find a route. The pathways and walls in a maze are fixed, and puzzles in which the walls and paths can change during the game are also categorized as tour puzzles. The Cretan labyrinth is the oldest known maze.

Creating a maze game on Scratch is easier than you might think. You only need the following instruction set for a basic gaming experience:

• One character to go through the maze. I suggest you replace the cat with another funny character. 
• To control your character movements, I suggest two options: add four arrows pointing in up, down, right and left directions; or control your character using the arrow keys on the keyboard. For more advanced users, try to develop both options.
• Insert a maze image in your stage. Depending on whether option to control your character you selected, a blank space on the stage will be needed. 
• If your character touches any wall, you loose. If your character reaches the exit, you win. 

Some blocks you´ll need

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Intro to Scratch Part 1

Scratch projects are made up of objects called sprites. You can change how a sprite looks by giving it a different costume. You can make a sprite look like a person or a train or a butterfly or anything else. You can use any image as a costume: you can draw an image in the paint editor, import an image from your hard disk, or drag in an image from a website. 

You can give instructions to a sprite, telling it to move or play music or react to other sprites. To tell a sprite what to do, you snap together graphic blocks into stacks, called scripts. When you double-click on a script, Scratch runs the blocks from the top of the script to the bottom.

Lets create a few initial projects, see the following videos to learn the basics:

Move your character

 Add sprites to your project

 

See more videos at: Tech Ed channel

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