THE PRESENT - COMPUTERS AS WE KNOW THEM

 

 

Personal computers were made possible by two technical innovations in the field of microelectronics:-

arrow21_R.gif the integrated circuit, 1958

 

arrow21_R.gifand the microprocessor, which first appeared in 1971

 

 

Move mouse cursor over the picture below, of a modern day integrated circuit, to see one of the first IC's ever made. .

chip.jpg

Developed, in part, by Jack Kilby, Texas Instruments, 1958, Nobel Laureate in Physics 2000, it was fabricated on a single piece of Germanium (approximately 5 x 11 mm) with protruding wires and glued to a glass slide.

 

 A microprocessor – also known as a CPU or central processing unit – is a complete computation engine that it fabricated on a single chip. The first microprocessor was the Intel 4004, introduced in 1971. The 4004 was not very powerful – all it could do was addition and subtraction, and it could only do that 4 bits at a time. Although, what was amazing at this time, was the fact that everything was on one chip

 

There are three very basic features of a microprocessor:-

die01b.gif    It can perform mathematical operations like addition, subtraction, multiplication and division. Modern microprocessors can perform extremely sophisticated operations on large floating point numbers.

die02b.gif    It can move data from one memory location to another.

die03b.gif    It can make decisions and jump to a new set of instructions based on those decisions.

 

Generally this is a small, thin piece of silicon onto which the transistors making up the microprocessor have been etched. A chip might be as large as an inch square and can contain tens of millions of transistors. Simpler processors might consist of a few thousand transistors etched onto a wafer of silicon just a few millimetres square. The below pictures show how small modern day silicon chips can be.

 

These chips are most usually made from a substrate of Si or GaAs, in the form of many thin layers of these semiconducting materials. The electrical properties of each and every layer is precisely controlled. The different layers are then etched to give the different components of the circuit. The various elements are then linked by a conducting layer e.g. aluminium alloy.  This ultimately leads to the production of wafer thin silicon chips, containing millions of transistors, which make up a computer’s microprocessor.

 

As manufacturing processes and materials advance the sheer number of transistors that can be etched onto a silicon chip rapidly increases in accordance with Moore’s Law. However THE FUTURE has in store much more than “x” number of transistors...