Category Archives: 1. Computer Systems

1. Computer Systems, Computing Higher

Scanners

OK, I admit it I went on a little about this 🙂

Here is a good post on the working of a scanner and in researching it I found that the video (below) in question was correct for colour CCDs.

[kml_flashembed movie="http://www.youtube.com/v/ZTWQbeE82HU" width="425" height="344" allowfullscreen="true" fvars="fs=1" /]

We will look at CCDs in more detail in next weeks lesson.

Here is a take apart that shows a LED scanner in more detail 🙂

[kml_flashembed movie="http://www.youtube.com/v/AuMkpaenqm8" width="425" height="344" allowfullscreen="true" fvars="fs=1" /]

1. Computer Systems, Computing Higher

Computer Structure – Main Memory

OK I may have went a little overboard on EEPROM 🙂 but it is very very useful. Some of you might think that EEPROM and flash memory is the same thing but you would be wrong. Have a look at this from webopedia

Pronounced double-ee-prom or e-e-prom, short for electrically erasableprogrammable read-only memory. EEPROM is a special type of PROM that can be erased by exposing it to an electrical charge. Like other types of PROM, EEPROM retains its contents even when the power is turned off. Also like other types of ROM, EEPROM is not as fast as RAM.

EEPROM is similar to flash memory (sometimes called flash EEPROM). The principal difference is that EEPROM requires data to be written or erased onebyte at a time whereas flash memory allows data to be written or erased inblocks. This makes flash memory faster.

1. Computer Systems, 3. Multimedia, Computing Higher, Revision

A couple of questions from today

Jonathan asked me a couple of very good questions today and I thought I would share my answers.

What is the difference between a linear CCD and a Array CCD?

  • A linear CCD is used in scanners and consists of a row of CCDs that moves down the document.
  • A CCD array is used in digital cameras and consists of a grid of CCDs as shown in this picture

Is it just CCDs that are used in digital cameras.

  • Some cameras use cheaper CMOS sensors, these sensors are not as fast and do not produce the same quality as a CCD. Wikipedia has this to say.

What does WRL stand for

  • This has taken a fair bit of research and the answer was on the blog the whole time… “World Description Language”. Personally I take the view of a lot of the websites WRL is the file suffix for VRML files and stands for WoRLd.

So with all this on the blog I updated the Multimedia Glossary, after all what else did I have to do.