8bit, 16bit, 32bit, what this numbers really mean..?

Most of us might already hear the term 32bit processor, 8 bit processor, AMD64, IA32, etc
We probaly know that the bigger the bit number, the better the performace of the microprocessor. But do we actually know what these bits number really mean and how it effect the overall performace of a processor..?

Processor communicate with the memory either internaly or external through what is call as address bus and data bus. The bigger the size of address bus, the bigger the memory size it can access. Example:- 16bit memory bus of 8052 microcontroller can access up to 65KB of memory.

Data bus on the other hand, is the bus that hold the data that will read or write from memory.
8bits data bus means that, at one particular read or write instruction cycle, only 8bits or 1byte can be transfer at one time.

Bits number of a processor represents the width or size of data bus

Below are list of processor or microcontroller that fall under 8bits processor:-
Intel 8088, Microchip PIC16F84A, Atmel AVR, Motorola 6800, etc

Basically it's conclude that, the bigger the data bus width, the faster the processor become because the huge number of bytes can be transfer at a time.

Microprocessor vs Microcontroller

This article will explain the different between microprocessor and microcontroller. Rather that we go straight to formal definition of both, it much easy to understand by looking at the example.
Below are names of microprocessor:-

Intel 8086, 8088, 80486, Pentium, Motorola 68000, AMD64

Below are names of microcontroller:-

Microchip PIC16F84A, Motorola MC68HC11, TI MSP430, Atmel AVR

Firstly, we describe what both have something in common. Both have a basic operations of a microcomputer. It has central processing unit, that fetch, decode, execute and writeback of machine instructions. It could be a simple loading data from memory and store to another locations. Or complex math operations to work on vector data.

The different between microprocessor and microntroller is the amount of peripheral that is put on a single IC (integrated circuits). The microprocessor IC alone wont make much use by itself. Other peripheral such as memory, video controller, ethernet,etc will make it become useful. With all this peripheral or support device connected together it will then become a router, PC, thin client,etc. Familiar stuff that we all see in our everyday life.

Microcontroller on other hand, have most of the peripheral put on the single IC. It has both volatile and non volatile memory, serial transceiver, general purpose IO, etc. By having all the peripheral inside, it will make the final device more compact, portable and low power. You could still design a blood pressure monitor or digital camera using a microprocessor but you will not get the shape and size that you see today on the device.

Why not make everything a microcontroller..?
Microprocessor is design in mind to do best in pure processing. It will have a very big data bus (32bit, 64bit), high clock speed, pipeline architecture, big instructions sets, etc. Much of silicon area on the IC are for this purpose, pure processing. In order to communicate with the outside, it has memory and data bus where all the peripheral can connected to. That's why the computer you are using able to run Microsoft Windows, open a word document, internet explorer and all sort of multitasking stuff.

Microcontroller is design to be as compact as possible. If you want to use a microcontroller as a digital camera, it has peripheral built into it for that purpose. By doing that, it will reduce the component count for the product. It also manage to make power consumption low and suitable for being portable and battery operated.

Embedded system example "Washing Machine"

In order to explain what is embedded system, it's easy to describe an everyday product that become and embedded system. For this I choose washing machine. Below is a sequence of activity of process that makes a typical washing machine (WM):-

1. Once finish loading all the dirty laundry inside, push START button
2. WM will measure the weight of the laundry to determine the load
3. WM will open the inlet valve to let the clean tab water into the WM
4. Once the water level reach certain level, base on the load measure in step 2, the inlet valve will close.
5. the rotating drum of the WM will move to start washing
6. once finish wash cycle, the outlet valve will open to release the dirty water
7. sensor will detect once all the dirty water been flush out to close the outlet valve
8. the inlet valve turn on to let clean water in for the rinse cycle.
9. once the water reach certain level, the inlet valve will close
10. the rotatiting drum of the WM will move to start rinse cycle
11. once finish rinse cycle, the outlet valve open to release the dirty water
12. sensor will detect once all the dirty water been flush out to close the outlet valve
13. step 8 - 12 will be repeated few times depend on the program setting
14. the rotating drum will move to start spin cycle
15. end of spin cycle, the WM process end. FINISH

All the above mention steps can be done manually but it will defeat the whole purpose of living in this century. The whole process can be fully automated, thank to embedded system. It transform our life to be very very efficient. Time save!!