Introduction to the PC

Introduction to the PC

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:
Mainframes are the very 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.

  • PC's are the Benjamin's in this order: Small inexpensive, mass produced computers. They work on DOS, Windows, or
    similar operating systems. They are used for standard applications.

The point of this history is, that Benjamin has grown. He has actually been promoted to captain! Today's PC's are just as
powerful as minicomputers and mainframes were not too many years ago. A powerful PC can easily keep up with the
expensive workstations. How have we advanced this far?
The PC's

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, itconquered the market. From being an IBM compatible PC, it became the standard.

An illustrated Guide to Motherboards. If we look at early PC's, 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 simpleoperating system MS-DOS.
Since the design was well documented, other companies entered the market. They could freely copy the central systemsoftware (BIOS) and the ISA bus, since they were not patented. Slowly, a myriad ofcompanies developed, manufacturingIBM compatible PC's and components for them.

The Clone was born. A clone is a copy-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 anothername (Compaq, Olivetti, etc.), or it has no name at all. This is the case with "the real clones." Today, we differentiate between:
Brand names, PC's 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.
Since the basic technology is shared by all PC's, I will start with a review of that.
The PC construction
The PC consists of a central unit (referred to as the computer) and various peripherals. The computer is a box, which contains
most of the working electronics. It is connected with cables to the peripherals.
On these pages, I will show you the computer and its components. Here is a picture of the computer: Here