Auxiliary Devices
Hello guys, if you are a computer operator. Then you know about the Auxiliary devices which are used in the Computer system. What type of secondary device is used in the computer system, and what are the required external devices for the computer system? This topic will find out on this page. So let’s get started to discuss auxiliary devices that are used in the computer operating system.
what is the auxiliary device?
It is also called auxiliary storage of computer systems, secondary storage on the computer, secondary memory for the computer or external memory, which is a non-volatile memory in the computer system( does not lose stored data when the device is powered down) that is not directly accessible by the CPU because it is no accessed via the input/output channels (it is an external device)
The auxiliary device is used to store a large amount of data at a low cost per byte than primary memory, secondary storage is two orders of magnitude less expensive than primary storage.
Magnetic storage of Auxiliary Devices
Magnetic Tape
- It is the type of magnetic storage device used in the computer system to store data and information.
- Commonly used secondary storage medium
- Used in a larger computer like a mainframe where a larger volume of data is stored for a long time
- Available in form of cassettes, reel
- Inexpensive
- Coated with magnetic material
- It is coated by plastic material on one side with also used iron oxide that can be magnetized
- Can be erased and reused
- 12.5 mm to 25mm in width and 500m to 2400 m long.
Advantages of magnetic tape
Compact ( much data stored per length)
Economical
Fast (coping data)
Long-term storage and reliability
Easy to handle
Disadvantages of magnetic tape
Affect by dust, heat, and humidity
Can’t be accessed by a human directly
Floppy Disk
- It is also a magnetic storage device.
- Generally used as secondary storage and backup storage media in microcomputer systems.
- Small, removable
- Popularly called diskettes are very thin flexible hence they are called floppy.
- Made of a thin film of plastic coated with a metallic oxide, kept in a square protective cover made of thin plastic called a jacket.
- Disk rotate freely in the jacket.
- Different size
- 5.25-inch diameter (1.2 MB)
- 3.5-inch diameter (1.44 MB)
- Cheaper
- Portable
Advantages of the floppy disk
- Random access processing is simple
- Easier to search for data
- Quick to data processing
How do work a hard disk in a computer system?
- Commonly used as secondary storage media in microcomputers and large computers.
- It is made of a metallic disk coated with metallic oxide ( iron oxide ) on both sides.
- Data are stored as magnetized spots arranged in concentric circles (tracks) on disk, each tack divided into sectors.
- A hard disk uses, a flat disk called platters, which are packed together and mounted on the common drive to form a disk pack.
- Platters are mounted by cutting a hole in the center and stacking them onto the spindle, platters rotate at high speed, driven by a special motor connected to the spindle.
- Special electromagnetic read and write devices called are mounted onto sliders and used to either record information onto the disk or read from it.
- The disk drive unit has more than one access arm, each access arm has two reads and Write head, on top of the platter and another on the bottom, so a hard disk with 3 platters with six surfaces and six heads, and each platter has its info recorded in concentric circles called tracks each track breaks down to smaller pieces called a sector.
- It is manufactured with a higher degree of precision.
- Isolated from outside air because of no contamination on platters which causes damage to the read and write heads.
- Lubricate is used to protect the hard disk in the inner track
- Speed of rotation about 3600 rpm
- Large storage capacity in GB, TB
- Have different sizes 8 inch, 5.25, 3.5 inches.
Optical Storage
Optical Storage is low storage memory. Which is used to store less amount of data on the computer. It is also an important device to store data and information. The optical storages areas Compact Disk Read Only Memory (CD-ROM)
- Stands of (CD-ROM)=Compact Disk Read Only Memory
- Is optical ROM which enables prerecorded data to be read.
- Is made of resin it is coated with (aluminum) material
- Data is permanent and can be any number of times, but CD ROM cannot be modified.
Read and write
A laser beam is used to write into or read from CD ROM. To write on disk 25 MW of laser ray, to read 5 MW of laser ray while writing high-density laser beam from tiny pit along the surface, the reflected laser is sensed by a photodiode which is known as a reading of data.
- Very high storing capacity
- Standard CD ROM can store up to 700 MB of data, 14500 tracks per inch.
- The diameter of cd 12 cm, weight 18 gm, 1 mm height
- CD ROM can read data 150 KB per sec.
- Three-dimensional pictures, videos films, graphs, animation, texts, numbers can be stored.
Advantages of CD ROM
- High storing capacities
- Less expensive
- Long life
- Can remove from the drive
- Reliable
The disadvantage of CD ROM
Access time is longer as compared to hard disk
It cannot edit data once written
DVD
- Stands for Digital Versatile Disk
- Higher capacity than the CD
- Same dimension as CD ROM
- DVD is double sides, Cds are single
- The capacity of DVD range from 4.7 to 17 GB.
How does it work?
- An optical disk mainly made of plastic, data is stored on a layer inside the polycarbonate plastic, metal layer reflects the laser light back to the sensor.
- To read data on disk, laser light shines through the polycarbonate and hits the data layer, the reflected light is absorbed is read 1 or 0.
- DVD has two data layers, can access the data from both sides.
- A double-sided DVD can hold 4 times more data than a single-sided one.
Flash memory
- Flash memory chip that holds its content without power.
- Derived from EEPROM technology
- Can be erased, less expensive
- Often called a flash drive, Pendrive.
Pen drive
- a flash memory device for storing and transferring audio, video, animation, photos, and data files from a computer.
- Often considered as an improvement of floppy and other Compact disk.
- As long as the desktop or laptop has a USB port, and the pen drive is compatible with the operating system, it should be easy to move the data from the hard disk to the device -and to another computer -in a matter of minutes.
- And they are small enough to fit into a pocket. Other names include a flash drive, a jump drive, and a thumb drive.
- Speed is in megabytes per second (MB/sec)
- Can be able to read and write
- Can move anywhere
- Storage capacities 2GB, 4GB, 8GB, 16GB, 32GB, 64GB, 128GB, 256GB are used.
