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.
Before we talk about different types of computers, let's talk about two things all computers have in common: hardware and software. 1  Hardware is any part of your computer that has a physical structure, such as the keyboard or mouse. 2  Software is any set of instructions that tells the hardware what to do and how to do it.