The point of this history is, that Benjamin has grown. He has actually been promoted to captain! Todays PCs 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 success
If we look at early PCs, they are characterized by a number of features. Those were instrumental in creating the PC success.
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:
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 is a list of the PC components. Read it and ask yourself what the words mean. Do you recognize all these components? They will be covered in the following pages.
|Components in the central unit - the computer||Peripherals|
|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),
|Keyboard and mouse.
External tape station
The von Neumann Model of the PC
Computers have their roots 300 years back in history. Mathematicians and philosophers like Pascal, Leibnitz, Babbage and Boole made the foundation with their theoretical works. Only in the second half of this century was electronic science sufficiently developed to make practical use of their theories.
The modern PC has roots that go back to the USA in the 1940s. Among the many scientists, I like to remember John von Neumann (1903-57). He was a mathematician, born in Hungary. We can still use his computer design today. He broke computer hardware down in five primary parts:
Actually, von Neumann was the first to design a computer with a working memory (what we today call RAM). If we apply his model to current PCs, it will look like this:
Data exchange - the motherboard
The ROM chips contain instructions, which are specific for that particular motherboard. Those programs and instructions will remain in the PC throughout its life; usually they are not altered.
Primarily the ROM code holds start-up instructions. In fact there are several different programs inside the start-up instructions, but for most users, they are all woven together. You can differentiate between:
All these instructions are in ROM chips, and they are activated one by one during start-up. Let us look at each part.
The suppliers of system software
All PCs have instructions in ROM chips on the motherboard. The ROM chips are supplied by specialty software manufacturers, who make BIOS chips. The primary suppliers are:
You can read the name of your BIOS chip during start-up. You can also see the chip on the system board. Here is a picture (slightly blurred) of an Award ROM chip:
Here is an AMI chip with BIOS and start-up instructions:
Let us look at the different components inside the ROM chip.
Read more about the boot process and system bus in Module 2b
Read more about I/O buses in module 2c
Read more about the motherboard chip set in module 2d
Read more about RAM in module 2e
Read about EIDE in module 5b
I also recommend two books for further studies. Gunnar Forst: "PC Principles", from MIT is excellent. Also "The Winn L. Rosch Hardware Bible" from Brady covers the same subjects. Also "PC Intern" from Abacus is fine.
Links to BIOS information:
Mr BIOS FAQ
Copyright (c) 1996-2005 by Michael B. Karbo. www.karbosguide.com.