A hard disk is a device that is used to store large amounts of data in a computer system. Hard disks differ from other memory because they are non-volatile; they retain the data even when they do not have power.
The data, which can be either just informational data, or executable programs, is written onto a spinning disk by making magnetic pulses very near the surface of the disk which make magnetized spots on the disk. The data is comprised of places which either are, or are not magnetized, yielding ones or zeros. The coils which make the magnetic field are on movable structures which "fly" above the disk, in that they are spring loaded to force them toward the spinning disk, but since actual contact would destroy both the coil and the disk, the structure is shaped like an airfoil (airplane wing), so that the relative wind from the spinning disk forces the coil structure just a small distance away from the disk.
Serial ATA (SATA) is a computer bus interface that connects host bus adapters to mass storage devices such as hard disk drives, optical drives, and solid-state drives.
To store information
My computer has all of your drives in your computer in the My Computer files. This can be accessed by going to start, my computer. Then you should see different drives like your hardware drives. Here you can access your program files and any floppy or USB drives you put into your computer.
In the computer's HARD
Computer storage devices are hardware components that store and retrieve data in a computer system. They function by saving data in a way that can be accessed quickly and efficiently by the computer's processor. This allows users to store files, programs, and other information for later use. Common types of storage devices include hard drives, solid-state drives, and USB flash drives.
It houses the motherboard, hard drives, power supply unit and other components.
The most common problem with large hard drives is computer crashes.
Assuming that when you say system unit of a computer you mean the computer case A.K.A. the tower, then no, hard drives are not always installed internally. Hard drives can be in external enclosures, hard drive docks, and even network attached devices.
The best place to visit about purchasing computer hard drives is an online website. A person can go on Amazon, Ebay, Newegg, or Bestbuy website to find the best place to visit about purchasing computer hard drives.
hard drives
The space inside the computer for DVD/CD/Floppy(who uses these anymore?) Drives and also Solid State Drives (SSD) and Hard Drives.
Depending on what computer you got but they are found inside the computer or tower.