Computers exist in a wide range of sizes and power. The smallest are embedded within the circuitry of appliances, such as televisions and wristwatches. These computers are typically pre-programmed for a specific
task, such as tuning to a particular television frequency, delivering doses of medicine, or keeping accurate time. They generally are ìhard-wiredîóthat is, their programs are represented as circuits that cannot be reprogrammed.
Mini Computers (Laptop, Notebook Computers and Desktop PCs) are typically used in businesses and at home to communicate on computer networks, for word processing, to track finances, and for entertainment. They are equipped with a keyboard; a mouse, trackball, or other devices; and a video display monitor or liquid crystal display (LCD) to display information.
Laptop and notebook computers usually have similar hardware and software as PCs, but they are more compact and have flat, lightweight LCDs instead of television-like video display monitors. If equipped with a cellular phone, they can connect to worldwide computer networks to exchange information regardless of location.
Workstations are similar to personal computers but have greater memory and more extensive mathematical abilities, and they are connected to other workstations or personal computers to exchange data. They are typically found in scientific, industrial, and business environmentsóespecially financial ones, such as stock exchangesóthat require complex and fast computations.
Mainframe computers have more memory, speed, and capabilities than workstations and are usually shared by multiple users through a series of interconnected computers. The most powerful mainframe computers, called supercomputers, control businesses, industrial works, scientific research and process complex
and time-consuming calculations, such as those used to create weather predictions. Large businesses, scientific institutions, and the military use them. Some supercomputers have many sets of CPUs. These computers break a task into small pieces, and each CPU processes a portion of the task to increase overall speed and efficiency. Such computers are called parallel processors. As computers have increased in sophistication, the boundaries
between the various types have become less rigid.