Chapter 1. The PC, history and logic

However, the technology is basically the same for all PC’s ?regardless of the manufacturer. And this common technology is the subject I am going to expound.

Finally, I just want to mention the term servers. They are special PC’s built to serve networks. Servers can, in principle, be built using the same components that are used in normal PC’s. However, other motherboards and a different type of RAM and other controllers are often used. My review will concentrate primarily on standard PC’s.

Bit width

The very first microprocessor Intel produced (the model 4004, also discussed on page 26) was 4 bit. This meant that in a single operation, the processor could process numbers which were 4 bits long. One can say that the length of a machine word was 4 bits. The Intel 4004 was a 4-bit processor with a 4-bit architecture. Later came processors which could process 8 bits at a time, like the Intel 8008, 8080, and not least, the Zilog Z80 (a very large number were sold). These were used in a large number of 8-bit computers throughout the 1970’s and well into the 1980’s.

The PC (in the 1980’s) was initially a 16-bit computer. With the development of the 80386 processor, there was a change to the 32-bit architecture which we are still using today.

Now there is a 64-bit architecture on the way, both from Intel (with the Itanium processor) and from AMD (with various Athlon 64 processors). But it is still too early to predict the extent to which the 64-bit architecture will spread into normal, Windows-based PC’s.

Width	Processor	Application
4 bit	4004	Pocket calculators
8 bit	8080	Small CP/M based home computers
16 bit	8086, 8088, 80286	IBM-compatible PC’s running MS-DOS
32 bit	80386 - Pentium 4	32 bit versions of Windows (Windows 95/98/2000/XP)
64 bit	Athlon 64 Pentium 4 Itanium	Server software 64 bits versions of Windows, Linux etc.

Fig. ?. Today’s PC’s use mostly 32-bit architecture.

The pre-history of computers

Our PC’s have “spiritual roots?going back 350 years. Mathematicians and philosophers like Pascal, Leibnitz, Babbage and Boole laid the foundations with their theoretical work.

The Frenchman, Blaise Pascal, lived from 1623-1662, and was a mathematical genius from a very young age. As an 18-year-old, he constructed a calculating machine, and his mathematical theories have had enormous significance to all later scientific research.

The Englishman, George Boole (1815-1864), was also a natural talent. He grew up in very humble surroundings, and was largely self-taught.

Another Englishman, Charles Babbage, began developing various mechanical calculating machines in 1823, which are today considered to be the theoretical forerunners of the computer. Babbage’s “analytical machine?could perform data calculations using punched cards. The machine was never fully realised; the plan was to power it using steam.

Fig. ?span style='mso-element: field-separator'>6. A construction drawing for one of Babbage’s calculating machines, which consisted of several tons of brass machinery.

However, it was only in the 20th century that electronics advanced sufficiently to make practical exploitation of these theories interesting.

In the 1930’ies Atanasoff was a professor of mathematics and physics at Iowa State University in the USA. Here he used the existing tools like the Monroe calculater and IBM tabulator for his calculations, but he found these machines too slow and inaccurate. For years he worked on the idea that there should better machines for calculation. His thought was to produce a digital machine, since Atanasoff had concluded that mathematical devices fell into two classes, analog and digital. The term digital was not invented, so he called this class of devices “computing machines proper?/p>

In the winter of 1939 Atanasoff was very frustrated from his lack of progress. After a long car ride (Atanasoff was fond of fast cars) he found himself drinking whisky in a bar (he was fond of scotch as well). Suddenly he had the solution. A machine built on four principles. It should work on base-two (binary) numbers instead of base-10 and use condensers for memory. Atanasoff teamed up with a brilliant young electrician Clifford Berry and later the 700 pounds machine called Atanasoff-Berry Computer was developed. This was the first digital computer.

Another pioneer was the German Konrad Zuse (1910-1995). He was only 18 when he constructed his own mechanical binary computer called Z1.

During the Second World War Zuse’s computer Z3 was used in the German aircraft industry. It was the first computer in the world to be programmed with software. It is interesting, that Zuse’s computers were developed entirely independent of other contemporary scientists work.

During the war, the Germans also used an advanced code machine (Fig. 8), which the English expended a great deal of effort on “hacking??They were successful, and this contributed to laying the foundation for the later development of computing.

An interesting piece of trivia: In 1947, the American computer expert, Howard Aiken, stated that there was only a need for six computers in the entire USA. History proved him wrong.