The Brain Behind The Computing: Technology

The Brain behind the Computing
The advent of semiconductor electronics can be traced baxck to 1947 when three young
scientists from Bell telephone labs invented the first semiconductor transistor (short for
transfer resistance). That started the cycle of miniaturization in electronics and today
what we have is an explosive growth in this technology. A growth that enables us to
manufacture microprocessors – an indispensable part of any automation industry.
Microprocessor is a highly integrated electronic chip that is an integral part of a computer

system. This chip is made of millions of small transistors etched on to a single silicon
wafer. Intel in late eighties was the first to come out with a microprocessor for a Japanese
calculator manufacturing company Busicom, which had asked Intel to build 12 custom
chips for their calculators. The engineers at Intel thought of integrating all the 12 chips
into one and they came up with Intel 4004 family of microprocessors. Thereon, Intel
never looked back and went on to make microprocessors we know as Pentiums. The Intel
8008 family was the first to make it to the home computers.
The technique used in making of a microprocessor has also come of age. When Intel
8008 was put together it was an 8-bit processor with 6000 integrated transistors whereas
today’s Pentium 4 is a 32 bit processor with 42 million integrated transistors on a single
silicon wafer.
Technology
Today the market offers a variety of microprocessors as per one’s need integrating the
latest cutting edge technologies. Despite all this, the manufacturers still manage to keep
the cost down.
As aforementioned, a microprocessor is an integrated circuit that is manufactured by

etching millions of transistors on a single silicon wafer. The width between these gates or
transistors is given in terms of unit called Micron, which is one-millionth of a meter. Intel
and AMD have released CPUs using 0.18 micron and Intel has re-introduced Pentium III
and Celeron using 0.13 micron chips. The advantage of using the small integration
technique is that only a small amount of charge is required to activate the gates. The low
power consumption ensures that the amount of heat dissipated is less. Theoretically, one
more significant advantage would be reduction in time required for data to flow from one
gate to another. This increases the overall speed and efficiency of the microprocessor.
How microprocessor works
The entire working of a processor can be divided into two parts – the software part and
the hardware part. The modules – that the microprocessor is made of – carry out the work
in a synchronized manner. This synchronism is provided by an external Clock Generator,
which generates clock signals for the CPU and other peripherals. And these modules are
made up of digital logical element blocks that carry out the calculations.
Software
We know that the application programs are written in higher-level languages like C, C++,
Visual Basic etc. The microprocessor is not capable of decoding these languages directly
and needs a translator to translate the program code into machine-level language i.e. the
binary language. This language is the native language of the CPU and consists of a string
of zeroes and ones for every instruction that the CPU understands. But as we humans
can’t remember all the series of codes for these instructions, an assembly level language
is used to give English like form – called Mnemonic form – to the instructions. For
example, the instruction for addition is given as ADD in assembly language whereas SUB
is for subtraction these are also called Operational Codes or Op-codes, which tell the
processor what action is to be performed on the data.
Hardware
All microprocessors irrespective of their manufacturing techniques have the same basic
building blocks and they are the digital logic circuits called logic gates., All these gates
require a minimum of one transistor. The output of these transistors can be either zero or
one, and the output depends on various combinations of inputs to these transistors. Hence
they can perform various logical operations based on Boolean algebra defined by Georgre
Boole. The main Boolean operators are AND, OR, Not, NAND etc. But during the
manufacturing of the processor, discrete transistors are not used. Instead, all these are
etched on a single silicon wafer using extreme ultra violet light.
Main components
The different parts and their functions of a CPU are as follows (see the diagram:
Functional blocks of a CPU):
Core: This is the central part of the Cpu, which houses the execution unit where all the
arithmetic logical unit and registers to store the instructions and operational data.
Floating Point Unit: This is the part of the CPU that does all the floating – point (non-
integer) operations. This unit determines the number crunching strength of a CPU.
Microcode and Pre-fetch Unit: The microcode is basically a decoder that decodes the
OIP-codes and tells the CPU what operation to be performed. All processor in the 80X86
family have a ‘Pipelined’ architecture that works on the First In First Out )FIFO) basis
and they line up the instructions ahead of its execution, the pre-fetching of the
instructions before they are executed.
Branch Processing Unit: This unit predcits the outcome of a conditional branch
instruction like a loop or a jump- and determines which code will be executed next so that
the pre-fetch unit can acquire the needed data in advance.
Cache: Today every processor has a small amount of high speed SRAM memory on the
chip used to store the instruction and data. This memory is called the L1 (level 1) cache.
Apart from L1 cache, the processor today contains an L2 cache which is often specified
by the manufacturers. It varies from 256KB to 512KB.
Bus and Bus Interface: Bus refers to the lines connecting the various internal blocks.
When these lines are connected to external devices like the main memory, they use a
buffer – acting as an interface. Thus it’s called bus interface.
Clock: It is the basic timing circuit of a computer system. It is generated by an external

clock generator chip and brings about synchronization between the various devices in the
CPU and the peripheral devices. The CPU basically goes through four stages when
performing any operation on the data: Fetch, Decode, Execute and Halt. In the Fetch
mode the CPU gets the required instruction and the data in the register. During the
Decode cycle it decodes the loaded instruction using the microcode unit and loads the
data to the execution unit. In the Execution cycle, the CPU performs the required
operation on the data and stores the result in the register or the main memory. After this
the CPU ‘halts’ and waits for the next fetch cycle.
Today every processor manufacturer provides a software utility to identify the processor
type, its speed and the various other multimedia extensions it supports. If you are using
an Intel processor then you can download a utility from Intel’s website clicking on
www.support.intel.com/support/processors/tools/frequencyid/downlaod.htm. If you are
using an AMD processor then you can download the utility from www.amd.com/us-
en/Processors/TechnicalResources/0,,30_182_871_2364~4563.html. Both utilities works
under Windows environment. Just install and run the program, and it will display the
summary of the processor.

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The Brain behind the Computing

Microprocessor is a highly integrated electronic chip that is an integral part of a computer

As aforementioned, a microprocessor is an integrated circuit that is manufactured by

How microprocessor works

Clock: It is the basic timing circuit of a computer system. It is generated by an external

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