Hard disk belongs to external memory and is not a necessary part of computer boot (boot here does not mean entering Windows operating system). The computer can be turned on without a hard disk, and the self-test should pass. After the self-check, if there are no other storage devices that can be started, the screen will prompt that the startup device cannot be found and report an error.

If a bootable U disk or CD is inserted at this time, the computer can run the operating systems and programs in these memories.

Memory is a necessary part of computer startup. If no memory is installed, the motherboard will continue to give out a "beep" alarm sound after booting, and the screen will not light up.

Extended data:

hard disc

English: Hard disk drive, abbreviated as HDD, is a nonvolatile storage device based on the rotation of the hard disk on the computer. It stores and retrieves digital data on a flat magnetic surface. Through the magnetic head close to the magnetic surface, the electromagnetic current writes information to the disk, and the information can be read in the opposite way.

For example, when the reading head passes the recorded data, the magnetic field causes the change of the electrical signal in the coil. The hard disk is read and written randomly, so the data in the hard disk can be read in any order [2]. The hard disk includes one or several disks rotating at high speed and a magnetic head placed on the cantilever of the actuator.

The storage medium of the early hard disk was replaceable, but today's typical hard disk uses a fixed storage medium, and both the disk and the magnetic head are encapsulated in the body (except for a filter hole to balance the air pressure difference caused by the heat generated during work).

Hard disk was used by IBM in 1956 [3], and became the main auxiliary storage device in general-purpose computers in the early 1960s. With the development of technology, hard disk also became the main component of servers and personal computers.

director

English: display? Device, an output device (output? Device) for displaying video and color. Common monitors are computer and TV screens. The earliest display was the cathode ray tube (CRT) of 1922.

Apple? I first brought the concept of monitor to the computer, not just a big box full of signal lights. Now it has developed to liquid crystal display and so on.

The screen size is calculated according to the diagonal of the screen, usually in inches. At present, the mainstream sizes are 17 ",19", 2 1 ",22", 24 "and 27", which refer to the diagonal length of the screen. Commonly used monitors include standard screen (narrow screen) and wide screen. The aspect ratio of the square screen is 4:3 (there are also some small ratios of 5:4), and the aspect ratio of the wide screen is 16: 10 or 16:9.

When the diagonal length is constant, the closer the width-height ratio is to 1, the larger the actual area will be. Wide screen matches the shape of human visual field.

References:

Computer Hard Disk-Baidu Encyclopedia

Display-Baidu Encyclopedia