Hard Disk & Flash Memory Storage
Two Types
- Internal Hard Disks
- External Hard Disks
Almost all PCs come with an internal hard drive that is housed inside the system unit and attached to the motherboard by a special cable. Most internal SSDs are either 2.5-inch or M.2 form factor. 2.5-inch drives connect to SATA ports and can replace old-school mechanical hard drives. M.2 drives look like RAM sticks and plug into dedicated M.2 ports.
External hard drives are easy to remove and connect to another computer so for this reason they are more flexible and portable. You would not need a PC technician to remove and re-connect external hard drives. If you don't have a large external hard drive or SSD, you should get one to do full system backups.
Hard disk drive (HDD)
A hard disk drive or fixed disk is a mechanical data storage device that stores and retrieves digital data using magnetic storage. The job of a hard disk is to permanently store data and programs on your computer.
Size
Most hard disk drives reside within a 3.5inch case and is found within the system unit attached to the motherboard. Hard disks for laptops are smaller and come in a 2.5 inch case. They were introduced by IBM in 1956.
Capacity
The storage capacity of modern hard disks is measured in gigabytes and terabytes but early PCs had hard disks of just around 10 or 20 mega bytes.(GB; 1 gigabyte = 1 billion bytes).
Speed
Hard disks are much slower than internal memory. A cache or buffer is used to increase the speed at which data is written to and read from a disk.
How HDDs work
The surface of each side of a disk also called platters is covered with a magnetized substance. The disks rotate at high speeds and may have one or more read/write fixed head.
Seek Time
The time it takes the head to get to the track on which the data is stored is called the seek time.
Flash Memory (SSD)
Flash memory storage devices are designed to store data without reading or writing on rotating disks as hard disk drives. Because there are not moving parts, SDDs are much faster and more reliable than hard disks which develop mechanical problems overtime and crash.
Flash memory is non volatile where data are persisted in the memory when power is turned off. Flash memory is Electronically Erasable Programmable Read Only Memory (EEPROM). When we think of flash memory storage we should think of SSDs, USB flash drives and memory cards.
EEPROM is used in USB flash drives, MP3 players and digital cameras and SSDs.
Solid-State Drive (SSD)
SSDs store data in semiconductor cells. A solid-state storage device uses integrated circuit assemblies to store data persistently. SSDs lack the physical spinning disks and movable read–write heads used in hard disk drives (HDDs). SSDs are typically more resistant to physical shock, faster and run silently compared to HDDs. SSDs use flash memory technology.
USB flash drive
Flash drives are referred to by different names which include pen drives, thumb drives, key drives. They are easy to use, small, fast and can hold large volumes of data. Newer flash drives hold 64GB, 128GB, 256GB and even 1 TB of data. Some flash drives include password protection and the ability to run software right off the USB drive itself. Many users use them to run the Linux operating system so that they are able to dual boot into either Windows 10 or a version of Linux such as MX Linux, Linux Mint, Pop!_OS, ubuntu or manjaro to name a few.
Flash memory cards
These cards are found in many digital cameras and smartphones. They are very small, protable, have high data capacity like flash drives and have a high data transfer speed.