Can I charge a computer through its USB port ?

Benjamin SchollnickNo Comments

I\’m aware of no computer that can be charged using the USB port.
Part of the reason for this, is that the power capacity of a USB connection is only up to 100 mA (milli-Amperes) at 5 volts, or half a Watt, or about 1/30 the power needed to actually run a typical laptop these days. Even the high Voltage ports on a Macintosh only
supply up to 12 Volts, and 1 Amp.
A Laptop charger typically supplies 19 Volts, and 4.5 Amps, or roughly 90 Watts….
As you can see, a dedicated laptop charger is significantly more powerful then the output of a USB port. And trying to feed that amount of power through a USB port would damage or destroy a USB port…
So, the answer would have to be that there are no laptops that can charge through the USB ports…

In the Limelight

Benjamin SchollnickNo Comments

You have heard the phrase \”In the LimeLight\”, but have you ever realized where it came from?
A Limelight, or Calcium light, is a type of stage lighting that used to be used in the live theatre.  The light is created when an oxyhydrogen flame is directed onto a piece of quicklime.  The quicklime can be heated up to 2572 degrees C before it will melt.
This obviously heats the quicklime to be white high, which produces the light…
Thus, when you are on stage, you were in the light from the limes.  limelight.

can\’t open the terminal? illegal value for shell? can\’t open /private/etc/sudoers?

Benjamin SchollnickNo Comments

One issue I have heard about, involves the /etc/ folder permissions being set to an \”bad\” value…
For example, if you set /etc/ to 755, Mac OS X will not allow a shell session (terminal) to be opened…  It will report \”The Administrator has set your shell to an illegal value\”.  If you try an sudo command, you will see an error (\”sudo: can\’t open /private/etc/sudoers: Permission denied sudo: no valid sudoers sources found, quitting\”).
What\’s the easiest way to resolve this?
If you are running 10.7, restart your system, and hold down the option key.  This will bring up the boot device list, choose your recovery partition (\”Recovery HD\”).  The \”Mac OS X Utilities\” menu will appear, highlight \”Disk Utility\” and hit Continue.   From the Disk Utilities left side bar, choose your hard drive (e.g. \”Macintosh HD\”).  In the \”First Aid\” pane, click on \”Repair Disk Permissions\”.
Repair Disk Permissions should repair the permissions issue, and allow you access to the Terminal / Shell sessions.
 

Job Seekers Getting Asked For Facebook Passwords

Benjamin SchollnickNo Comments

What would you think of an interviewer if they asked for your Twitter, Facebook, or LinkedIn account passwords?
Sounds far fetched doesn\’t it?  It isn\’t though.

Since the rise of social networking, it has become common for managers to review publically available Facebook profiles, Twitter accounts and other sites to learn more about job candidates. But many users, especially on Facebook, have their profiles set to private, making them available only to selected people or certain networks.
Companies that don\’t ask for passwords have taken other steps — such as asking applicants to friend human resource managers or to log in to a company computer during an interview. Once employed, some workers have been required to sign non-disparagement agreements that ban them from talking negatively about an employer on social media.

Read the rest of the article, at Job Seekers Getting Asked For Facebook Passwords

WebKit Limit on [iPad] Retina JPG Image Display

Benjamin SchollnickNo Comments

Evidently there is a limitation with the new iPad (nee iPad 3), which can cause JPEG images to be resampled, when viewed through Webkit (mainly Mobile Safari, but other applications can use Webkit).
These have to be huge images though….  For example, 2000×1000…. So these aren\’t your normal run of the mill images…  Progressive Scan JPegs, and PNG\’s don\’t seem to be vulnerable to this.  Just Classic Jpegs…
Take a closer look over at Duncan Davidson\’s blog for more information….