Week 2:
Computer basics

Just enough information to get along with.

Note: In general, the information below applies both to Macs and PCs

 

When you want to acquire a passing acquaintance with computer systems, it is useful to divide the information available into three categories:

 

The stuff in the box

CPU (Central Processing Unit)
The CPU is the microprocessor that "runs" the computer. Everything that happens on the machine is overseen by the CPU

Memory
This is fast-access storage connected to the CPU. The calculations that happen in real-time when you are using software on your computer happen in the memory. This is why some software that carries out a lot of heavy-duty calculation, such as video software, requires huge amounts of memory. The main chunk of memory, and the one that effects the speed of your computer is RAM (Random Access Memory). Only data to do with the work the computer is carrying out currently is kept in RAM, which is then emptied, ready for use again.

Sometimes, very frequently used data is stored in another area of memory called a Cache, so that it is possible to access it even more quickly.

Hard Drive(s) or Hard Disks
Hard drives are storage areas for data and software. The CPU cannot access these storage areas as quickly as the memory.

Virtual Memory
This is not actually physically part of the memory chip in the computer. It is a part of the hard drive that can temporarily be used as memory for calculations that require more processing space than is available in RAM.

Photoshop, and many other programs that require a lot of memory, use virtual memory (scratch disks). When you set the scratch disks (Edit/Preferences/ Plug-ins & Scratch Disks) this "permits" Photoshop to use some space on the specified hard disk as memory when necessary. If you get an error message in Photoshop that says your scratch disks are full, it means that there is so much data stored on the hard drive that the area you agreed to make available as virtual memory from time to time is now full of other stuff. This in turn means that Photoshop has not now got enough memory available to perform the operation you requested.

 

Operating System
The basic software that allows the user to interface with the computer. Operating systems provide the user with a metaphor for understanding how to work in the computer environment. The metaphor of the desktop is so familiar to us that we sometimes forget that it IS a metaphor.

The operating system on a PC is Windows. The operating systems on an Apple is the Mac Operating System. They both use the desktop metaphor and the idea of storing data in folders or directories, but they have implemented it in slightly different ways.

Software
Computer programs designed to help you to achieve certain tasks.
e.g. MS Word is Word Processing software
Adobe Photoshop is Image Manipulation software.

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The stuff hanging out of the box

Input/Output devices
The hardware that you use to communicate with the computer.

The key types are

  • Screen (output)
  • Keyboard (input)
  • Mouse (input)
  • Printer (output)
    Removable storage (can be both input and output)
    • Floppy Disk
    • Zip disk
    • CD
    • DVD
    • Memory stick/Flash memory/USB key

 

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A whole pile of boxes connected together

Network

A LAN (Local Area Network) is a group of computers, usually in a single building or organisation, which are linked together to allow them to communicate with each other.

The IADT LAN is based on the Client/Server model. The machines we work on are Clients - they provide some functionality, such as locally installed software and Internet access, but the main storage areas for the network are on dedicated machines called Servers, to which the users of the network have no physical access.

When you log in to a machine in college, you connect to a particular Domain (INSTITUTE). This is a particular area of the network to which you are entitled to have access.

On the INSTITUTE domain, you have a dedicated storage area. When you log in to any machine, it "recognises" who you are from your ID and password, and "shows" you your own storage area, which physically resides on one of the server computers in the network. The beauty of the LAN is that you can see your own space from any machine. This means that if you create a document or an image on a machine in the library, say, and save it to your own space, you can retrieve your work from any other machine.

Each student’s storage area on the network is set to a fixed maximum size. If you exceed that amount of data, you will get error messages when you try to save anything new. You will have to delete some data from your storage area to make room for more.

A WAN (Wide Area Network) is a group of connected computers distributed over a wide geographical area. The Internet is the world’s largest WAN.

Firewall
A network firewall protects a computer network from unauthorized access. Network firewalls may be hardware devices, software programs, or a combination of the two.

Network firewalls guard an internal computer network (home, school, business intranet) against malicious access from the outside. Network firewalls may also be configured to limit access to the outside from internal users.

The IADT firewall may prevent activities such as uploading files to the Internet or downloading files from the Internet.

 

Further reading

For more details, visit
How Stuff Works