Most of the equipment used by a microcomputer is tightly integrated within a single case, although some equipment may be connected at short distances outside the case, such as monitors, keyboards, mice, etc. In general, a microcomputer will not get much bigger than can be put onto most tables or desks. By contrast, bigger computers like minicomputers, mainframes, and supercomputers may take up some portion of a large cabinet or even an entire room.
Most microcomputers serve only a single user at a time, but some, in the form of PCs and workstations running e.g. a UNIX(-like) operating system, may cater to several users concurrently. The µP does most of the job of calculating on and manipulating data that all computers do. Along with the CPU, a computer comes equipped with two types of data storage, a very high-speed, volatile device known as RAM, and lower-speed non-volatile devices known as disk drives.
Other devices that make up a complete microcomputer system include its power supply, and various input/output devices that are used to convey information to and from a human operator (printers, monitors, human interface devices).
The world's first commercial microprocessor was the Intel 4004, released on November 15 1971. The 4004 processed 4 binary digits (bits) of data in parallel; in other words, it was a 4-bit processor. At the turn of the century 30 years later, microcomputers in embedded systems (built into home appliances, vehicles, and all sorts of equipment) most often are 8-bit, 16-bit or 32-bit. Desktop/consumer microcomputers, like PCs, are mostly 32-bit, while some science/engineering workstations as well as database and financial transaction servers are 64-bit (with one or more CPUs).
The first generation of microcomputers, for engineering development and hobbyist personal use, was launched in the mid-1970s; the MITS Altair being the most well-known example. 1977 saw the introduction of the second generation, known as home computers. These were considerably easier to use than their predecessors, whose operation often demanded thorough familiarity with practical electronics. It was the launch of the VisiCalc spreadsheet (initially for the Apple II) that first turned the microcomputer from a hobby for computer enthusiasts into a business tool. After the 1981 release by IBM of their IBM PC, the term Personal Computer became generally used for microcomputers compatible with the IBM PC architecture (PC compatible).