Microprocessors

How many of us have come across the term, microprocessor based technology written on washing machines, or dishwashers etc. They are there almost everywhere, from toasters to microwave ovens to aircrafts and satellites. But what is a microprocessor, well in layman terms; it is central core vital element for a system to get functioning. Celeron, Pentium, Sparc, Power Pc etc are a few names of some microprocessors.


HISTORY OF MICROPROCESSORS:

When a microprocessor was first introduced, it was called as a Central Processing Unit or a CPU. The technology behind this that makes Microprocessors so special is that the entire unit is based on one single chip. Intel was the first company to have introduced the world to the technology of microprocessors; they had named this budding baby Intel 4004. At that time the basic functions that it could compute was just addition and subtraction. The year was 1971, and this was the time that electronic calculators were much in use, but they were all transistors which were wired one at a time, and assembled together, so to have the entire system working with just one chip was just amazing.
And then as time progressed, then came Intel 8080, and this was the first time that it was used in a home computer. This was a 8 bit chip. Then came in so many more 8080 to 8086 to 8088 to 80286 to 80386 to PI to PII to PIV. And with each new version, the speed only increased. Survey records have shown that PIV is 5000 times more faster that the 8088.

The following are a few terms that are always found when referencing to microprocessors and they are
Chip
IC or Integrated Chip is also a synonym for a chip
It has a number of transistors loaded on to it.
The chip usually is a thin strip that is usually made up of silicon and they carry the transistors, which have been fixed on to them
In size they may vary from a few square millimeters to an inch

Transistors
These are the number of PNP or NPN circuits on the chip.

3. Microns
· It is a unit of measurement of the width of the smallest wire that is based on the chip. The lesser the number of microns, the more the space available for the transistors.

4. Clock Speed:
· it is the rate at which a chip can be timed.

5. Data Width Data
· It is the width of the number of bytes. That is whether the chip is 8 bit or 32 bit, thus implying that the more the width, the more the manipulations.

6. MIPS
· "millions of instructions per second" that gives a general idea about the performance of a CPU


HOW DO MICROPROCESSORS WORK


The basic components of a typical microprocessor are
Address Bus: This is a bus that sends address to memory. It may be 8/16/32 bit.
Data Bus: This is a bi directional line that sends data to memory or vice versa. It may also be 8/16/32 bit
Read Line/Write Line: It tells the memory whether to set or to get the addressed location
Clock Line: Sets up pulses for the processor for the clock to be sequenced.
Reset Line Used to reset Program Counter to start or 0
Registers they are simple latches that are made out of flip flops.
Microprocessor Memory RD/ WR are the lines that are connected RAM / ROM or both
ROM is also known as Read Only Memory and as the name suggest, it only reads.
RAM is Random Access Memory Since information stored on this is valid only for one session till the power unit is on; the data is then usually stored on ROM
The ROM is also called as the BIOS in a PC (Basic Input/Output System).

A microprocessor basically understands only MLL or Machine Level Language.
The most common activities are the ALU (Arithmetic Logic Unit) Operations, else floating point operations as in little high qualified microprocessors, moving of data from one location to another , making decisions, jumping, timing etc.


Microprocessor Instructions

The following are the set of instructions that are common to almost all microprocessors

LOAD A mem - Load register A from memory address
LOAD B mem - Load register B from memory address
CONB con - Load a constant value into register B
SAVE B mem - Save register B to memory address
SAVE C mem - Save register C to memory address
ADD - Add A and B and store the result in C
SUB - Subtract A and B and store the result in C
MUL - Multiply A and B and store the result in C
DIV - Divide A and B and store the result in C
COM - Compare A and B and store the result in test
JUMP addr - Jump to an address
JEQ addr - Jump, if equal, to address
JNEQ addr - Jump, if not equal, to address
JG addr - Jump, if greater than, to address
JGE addr - Jump, if greater than or equal, to address
JL addr - Jump, if less than, to address
JLE addr - Jump, if less than or equal, to address
STOP - Stop execution


Decoding

Decoding is about decoding the opcodes into a sequence of signals that make the components in the microprocessor function. Example is the ADD instruction, which is explained below
First the Program Counter is set,
The Rd line is activated
The data in buffer is set
The Add instruction is decided by setting the counter to addition operation in the ALU
The O/P is latched to the O/P register generally C
Program Counter is increased.


Well today microprocessors do follow so many architectures, they have 1 GB RAM, too many transistors to increase the pipelining, they follow the MMX instruction sets, thus are alls et to take the world in their stride and are definitely here to race time