Ports are of different types and are of different shapes and sizes
A few examples are:
Main Processing Unit Devices - Modem
Modems can be External (connected by a lead to a Port) or Internal (fixed to a slot on the Motherboard)
A modem allows a computer to send and receive data through a telephone line.
Modems transmit data at different speeds known as Baud Rate.
Speed is measured in Bits per Second or bps.
It is common for modems in the home to transmit and receive data at 56 Kbps.
External modems are becoming less common because most new computers come with an internal modem already fitted to the Motherboard.
Modems are a common way to connect to the Internet.
Other methods include Cable and ISDN, however this is an area of computing that is constantly changing as new technologies become available.
Main Processing Unit - Network Interface Card
It is possible to link computers together so that data can be transferred between them and so that other devices such as printers can be shared.
Network Interface Card
To connect computers together the computers each need a network interface card (NIC) like the one above.
There are different types of network cards for different types of networks!
The card plugs into a slot on the motherboard. It has a port which allows for a suitable connector and cable to then connect the PC to a network device.
Storage Devices - Floppy Disk
These are cheap ways of storing things but can only hold 1.44 Mb of data.
Inside the plastic casing is a small disk which has a surface which can store magnetic patterns.
When inserted into the computer, the metal sleeve slides across to reveal a part of the disk to a read/write head. The disk spins round within its casing and the head can move back and forth.
Casings come in different colours but the most common are black and blue.
Most computers have a floppy disk drive and this means the floppy disk is a cheap way of moving or copying small amounts of data from one computer to another. They can also carry computer viruses between computers so BEWARE!
Storage Devices - Hard Disk
Hard Disks have the capacity to store lots of data.
The one in the picture above can store 10Gb.
Hard Disks have a smooth surface which, like floppy disks, can be magnetised so they can be used to store data over and over again.
Hard Disks are usually fixed inside the computer and are connected to the Motherboard with a ribbon cable. The Hard Disks rotate and as they do so read/write heads move back and forth across the surfaces to store and retrieve the data.
External Hard Disks can be attached to an appropriate port.
This makes them more portable but takes up space.
Most modern computers have at least one Hard Disk.
Usually, application software such as Word, Excel and Access are stored on the Hard Disk.
If a computer has more than one Hard Disk then one must be designated as the
'Master' and any others as 'Slaves'.
Storage Devices - CD ROM
CD ROMs store a large amount of data.
Most computer games are now purchased on CD ROMs.
Data is stored optically which means that it is read by using a laser.
The CD ROM is placed inside a drive and the disc rotates at high speed.
A laser light and sensor moves back and forth as the disk rotates in the drive.
A standard CD ROM can hold 650Mb of data but it is possible for some CD ROMs to hold up to 1Gb of data. On average one CD ROM can hold as much data as could be held on 450 3.5" Floppy Disks!
The surface of the disk appears smooth but in fact it is quite uneven and it is the depth and distribution of marks in the surface which the computer reads as coded information.
The quality of the laser and the speed at which the disk rotates affects the performance and speed with which data can be retrieved. Information is only held on one side of the disk.
It is now popular to connect a CD Writer to your PC so that you can save data to your own CDs. This can include images, documents, spreadsheets etc. Copyright of material and pirate copying has become a big issue as a result of this technology being so commonly available.
Once produced or 'pressed' a standard CD ROM cannot be overwritten.
CD ROM shares the same technology as Audio CDs so an Audio CD can be played in a computer CD ROM Drive. Data CD ROMs should not however, be used on Audio equipment.
A DVD ROM is able to store a massive amount of data, typically about 4.3Gb.
This is roughly the same as about 6 or 7 CD ROMs!
DVD ROM technology was originally designed to hold high quality video.
DVD ROMs store data optically. Once placed in a DVD ROM Drive the DVD rotates and a laser light moves back and forth to read the information. Information can be stored on both sides of the disk unlike CD ROM which can only store information on one side.
DVD drives operate at different speeds which means the speed at which data can be retrieved varies.
The quality of the laser also affects the performance.
DVD ROMs often hold information like movies in an encrypted format.
This is to try and stop pirate copies of copyright material being made.
Many DVD ROM Drives are fitted inside the casing of the Main Processing Unit with a cable connecting the drive to the Motherboard.
Once 'pressed' with new data DVD ROMs cannot be erased and refilled with different data.
It is generally accepted that DVD ROM technology will replace CD ROM technology in the next few years.