The technical term for a PC is micro data processor . That name is no longer in common use. However, it places the PC in the bottom of the computer hierarchy:
- Supercomputers and Mainframes are the largest computers - million dollar machines, which can occupy more than one room. An example is IBM model 390.
- Minicomputers are large powerful machines. They typically serve a network of simple terminals. IBM's AS/400 is an example of a minicomputer.
- Workstations are powerful user machines. They have the power to handle complex engineering applications. They use the UNIX or sometimes the NT operating system. Workstations can be equipped with powerful RISC processors like Digital Alpha or MIPS.
The PC's success
The PC came out in 1981. In less than 20 years, it has totally changed our means of communicating. When the PC was introduced by IBM, it was just one of many different micro data processors. However, the PC caught on. In 5-7 years, it conquered the market. From being an IBM compatible PC, it became the standard.
If we look at early PCs, they are characterized by a number of features. Those were instrumental in creating the PC success.
- The PC was from the start standardized and had an open architecture.
- It was well documented and had great possibilities for expansion.
- It was inexpensive, simple and robust (definitely not advanced).
The PC started as IBM's baby. It was their design, built over an Intel processor (8088) and fitted to Microsoft's simple operating system MS-DOS.
Since the design was well documented, other companies entered the market. They could produce functionable copies (clones) of the central system software (BIOS). The central ISA bus was not patented. Slowly, a myriad of companies developed, manufacturing IBM compatible PCs and components for them.
The Clone was born. A clone is a copy of a machine. A machine, which can do precisely the same as the original (read Big Blue - IBM). Some of the components (for example the hard disk) may be identical to the original. However, the Clone has another name (Compaq, Olivetti, etc.), or it has no name at all. This is the case with "the real clones."
Today, we differentiate between:
· Brand names, PCs from IBM, Compaq, AST, etc. Companies which are so big, so they develop their own hardware components.
· Clones, which are built from standard components. Anyone can make a clone
Components in the central unit - the computer
The motherboard: CPU, RAM, cache, ROM chips with BIOS and start-up programs. Chip sets (controllers). Ports, buses and expansion slots.
Drives: Hard disk(s), floppy drive(s), CD-ROM, etc.
Expansion cards: Graphics card (video adapter), network controller, SCSI controller. Sound card, video and TV card. Internal modem and ISDN card.
Keyboard and mouse. Joystick Monitor Printer Scanner Loudspeakers External drives External tape station External modem
Key Functions of a PC:
Before looking at specific PC components, it is worth taking a few moments to consider the key functions that are performed by a computer:
Input - Entry of raw data; for example, typing names and addresses on a keyboard or transmitting a picture from a digital camera.
Processing - Manipulation of the raw data to produce useful information, the key purpose of a computer; for example, sorting or indexing the names and addresses or adding effects to the picture.
Output - Transformation of the data into information, perhaps in a non-computerized format; for example, printing mailing labels from a database or displaying the picture in a brochure
Storage - Retention of the data until it is needed; for example, filing names and addresses in a database or archiving the picture in an online library. With a basic understanding of these key functions, the role of each of the components of a PC becomes much clearer