There are different types of storage devices available, these include…

Magnetic storage devices, that can be fixed or removable.  Removable storage devices allow the user to disconnect the device and physically transport data from one one computer to another.  Examples of magnetic storage are shown in the image below.

The speed of magnetic storage has improved, with hard disks being used everyday internally and externally in computer usage.  Early disks used to have about 3000 revolutions per minute but now it is not uncommon to see hard disks reaching speeds of up to 5400rpm or even better 7200rpm.

Capacity of hard disks have improved tremendously also in the last 10 years.  From a mere 10Mb in the 80’s to 8Gb on many of today’s pc’s.

NOTE: Remember when writing about capacity that mb = megabits & Mb = megabytes!

Optical storage devices are used commonly everyday, be it in video games or music cd’s we have all used optical storage at least once.  The most common optical storage device is the CD-ROM (Compact Disk Read-Only Memory), which is a read only format which, once written to, cannot be altered.  When writing to optical storage, the process is called burning.  A high power laser is used to do this.  To read the disc however, a low power laser is used – an infrared light is shone onto the disc which contains a long spiral curled round it containing all the data.  When the infrared light finds data it reads it and trys to make use of the data.

Here are some examples of optical storage:

CD-ROMs have been overcome by the creation of writeable CDs, called CD-RW.  The capacity of CD-ROMs are typically 650Mb. DVDs typically 4.7Gb and Blu-Ray 25Gb all when based on single layer.

Optical storage is usually read only.

Solid State Storage Devices (SSSD) are made up entirely of electronic parts, meaning they have no moving parts.  Also known as RAM disks, they can take the place of a magnetic disk as a mass storage device.  They can be in the form of a plug-in card or cartridge containing memory chips.  SSSD run on Static RAM or Electrically Erasable Programmable ROM.  SSSD are ideal if portability is needed as USB is widely used in all formats of computer and memory cards are used to save space in small devices such as digital cameras.  Here are some examples of SSSD:

SSSD is great for capacity as it is very cheap.  USB flash drives with a 2Gb capacity can cost as little as £3 and external harddrives with up to a terrabyte of space can cost only £50 in some shops.

We began the lesson by talking about writing good blogs which should include graphics, examples, etc. To put images onto the blog you must first download them, and then upload them directly from your PC and do not use URL’s as if the source website changes that image your blog post will also change. Another improvement to blogging is to re enter your blog and tag it so other users will be able to find relative information to their query. We got told that the documentation is very important in software development and that we need to write about every stage in detail as it is needed to gain a good mark. All the course notes were given out last week and if you didn’t receive them you should contact your computing teacher. These are also needed to have good preparation for the upcoming prelim after the Christmas break. Also the course work task is coming up in about 3 week’s time. We finished off interfacing but will come back to it at any opportunity as it is touched on in many SQA Higher Papers. We also discussed the USB and USB2 interfacing in addition to this. This relates to Apples FireWire which is a copyrighted part of their business. We then started on wireless networking, talking about mobile networking in the past, blue tooth (a personal area network that works within 10 meters of the device) and Infrared etc. A wired network is much more secure than a wireless network as hackers can simply connect to a wireless network easily if it is not password protected whereas a wired network would require a cable into the system. Different devices operate on different frequencies to stop interference thus radio stations need to buy their frequency to stop two stations being the same so you can select which one you want to listen to without hearing the rest. As many people have Bluetooth the two devices that are wanted to interact with each other must be synced. Since they are synced they can change their frequency often (lots of times a second) to avoid interference with other devices. Notes on advantages of blue tooth can be found in topic 4.6.8 on page 100. There is a chance of interference in devices connected wirelessly so keyboards, mouse’s, etc are more secure if wired especially if in use in schools, offices and other crowded places with lots of computers. After this we searched the internet for wireless devices that uses clever interfacing and ways of connecting. Some found were wireless headphones, keyboards, mouse’s, phones and various devices.
Homework was issued and is available on the Glow Scotland website.

You should now have the following core notes.

Software Development

• Topic 1 Getting started
• Topic 2 Strings and Branches
• Topic 3 Loops (revision)
• Topic 4 1-D Arrays (revision)
• Topic 5 User-defined functions
• Topic 6 Sub-programs and parameter passing
• Topic 7 Standard Algorithms
• Topic 8 Real-world Programming
• Topic 9 Programming tools

Computer Systems

• Topic 1 – Data representation
• Topic 2 – Computer Structure
• Topic 3 – Computer Performance
• Topic 4 – Peripherals
• Topic 5 – Networking
• Topic 6 – Using Networks
• Topic 7 – Systems Software
• Answers
• Glossary

Today we learned about interfacing which is making the appropriate connections so that two pieces of equipment can communicate or work together effectively.

The example shown was a Kinect.

The types we learned about were serial interfacing where data is sent individually and parallel where it is sent in multiple bits.
We also discussed analogue and digital interfacing.

We were then handed out the rest of the notes.