Basics of 8051

Microcontroller VS Microprocessor

In Embedded System field the question which often arise in our mind, that what is the difference between Microcontroller and Microprocessor?

Microprocessor is meant the general-purpose microprocessor like x86 family (8086, 80286, 80386, 80486, and the Pentium) or Motorola’s 680x0 family (68000, 68010, 68020, 68030, 68040, etc.). These microprocessors contain no RAM, no ROM, and no I/O ports on the chip itself. For this reason, they are commonly referred to as general-purpose microprocessors.

A system designer using general-purpose microprocessors such as Pentium or the 68040 have to add RAM, ROM, I/O ports, and system timers externally to make them functional. Although the addition of external RAM, ROM, I/O ports makes these systems bulkier and much more expensive, they have the advantages of versatility such that the designer can decide the amount of RAM, ROM, and I/O ports needed to fit the task at hand.

But a Microcontroller has a CPU (a microprocessor) in addition to a fixed amount of RAM, ROM, I/O ports, and timers all in a single chip.

Now come to 8051 Microcontroller, which is the well-known microcontroller in educational and industrial field. If we want to learn Embedded System, then first we have to learn 8051 very carefully and consciously. Let’s start……………………………………………………………

8051 Microcontroller

History of 8051

In 1981, Intel Corporation introduced an 8-bit microcontroller called the 8051.This microcontroller had….

RAM à 128 bytes

On-Chip RAM à 4K

No. of Timers à 2

No. of serial ports à 1 (each 8-bits wide)

Total No. of I/O Ports à 4 (each port have 8 pins)

Total No. of pins à 40

Interrupt sources à 6

Although the 8051 can have a maximum of 64K bytes of on-chip ROM, many manufacturers have put only 4K bytes on the chip. This will be discussed in more detail later…..

There are many members in 8051 family like 8052, 8031, etc. but in this we will discuss about 8051 only..

There are so many chips in 8051 series like AT89c51, AT89s52, AT89c2051 etc. , they have different values of RAM, ROM and have different numbers of pins and ports.

In the next topic we will discuss about coding. How to code for a microcontroller.

                If you have any doubt about this topic, don’t hesitate to comment. See you in next topic…