4. Has a rigid cell wall made of peptidoglycan (except for the mycoplasma). This cell wall is thick in Gram-positive bacteria and thin in Gram-negative bacteria. It is the thickness of the peptidoglycan that accounts for the ability/lack of ability to retain the crystal violet used in the Gram stain.
Computer hardware is the physical parts or components of a computer, such as the monitor, mouse, keyboard, computer data storage, hard disk drive (HDD), graphic cards, sound cards, memory, motherboard, and so on, all of which are physical objects that are tangible.
(1) A group of related components that interact to perform a task. (2) A computer system is made up of the CPU, operating system and peripheral devices. All desktop computers, laptop computers, network servers, minicomputers and mainframes are computer systems. Most references to computer imply the computer system.. See computer system.