Hard Disk Drive
Hard Disk drive is a secondary storage device used to store data permanently . It is non-volatile storage device which means it will retain data when computer is turned off . It is also known as hard drive. It is electro mechanical storage device which stores or retrieves data on coated magnetic plates . A ready/write head charges the disk ‘ surface with positive or negative charges , this is how binary 1 or 0 represented . Typically hard disk drive capacities are measured in Terabytes ( TB ) .
Applications of Hard Disk Drives
- Desktop computers
- Laptop computer
- Tv and satellite recorders
- Servers
- Mainframes
Advantages of Hard Disk Drives
- Large capacity
- Faster than optical disk like DVD
- Persistent storage
- Easily replaced and upgrade
Disadvantage of Hard Disk Drives
- Relies on moving parts
- Disk surface can be damaged
- Heavy power consumption
- Noisy
- Slower read and write speed than RAM
Solid State Drive (SSD)
Solid state drives are non-volatile storage devices capable of holding large amounts of data . It is new generation of storage devices . SSD uses flash based memory which is much faster than traditional Hard Disk . SSD has increased the speed of computer systems because it can access data rapidly as compared to magnetic plates . SSD is connected to computer using standard IDE or SATA connection .
Applications of SSD
- Smartphones
- Tablet computers
- Latest laptop
- Two drive desktop solutions
- HD video cameras
Advantages of SSD
- High speed
- More durable
- More noise
- Low power consumption
Disadvantages of SSD
- Expensive
- Less storage space than HDD
- Limited life span
- Data Recovery is near to impossible
USB Flash Memory
USB is also non-volatile solid state storage devices . It is plug and play device which means we don’t need to run a USB device . Its storage capacity is up to 1 TB .
Applications of flash memory
- USB memory stick — saving and transferring documents etc
- Memory cards in digital cameras
Advantages of USB Drive
- Cost effective
- High speed
- Suitable size
- Less noise
- Plug and play
Disadvantages of USB drive
- Source of spreading malware
- Limited life span
- Security threats
- Risk of losing
Control unit
Control unit ( CU ) manages the entire functioning of the computer system . It is one of the most essential components of the computer system . The Control Unit collects the data entered using the input unit , leads it on for processing and once that is done , the output is presented it to the user . It can be considered the center of all processing actions taking place inside a computer device .
Basically , the instructions taken , interpretation of entered data , issuing signals to execute the data and finally retrieving the data is all done in the Control Unit .
