As all the peripheral of microcontroller are on single chip it is compact while microprocessor is bulky. Processing speed of microcontrollers is about 8 MHz to 50 MHz, but in contrary processing speed of general microprocessors is above 1 GHz so it works much faster than microcontrollers.

Many admins use CPU and microprocessor interchangeably, but the reality is that while a CPU is essentially a microprocessor, not all microprocessors are CPUs.

A microcontroller (MCU for microcontroller unit) is a small computer on a single metal-oxide-semiconductor (MOS) integrated circuit (IC) chip. A microcontroller contains one or more CPUs (processor cores) along with memory and programmable input/output peripherals.

Microcontrollers combine these elements into one chip, so in some sense that makes the term accurate. The reality is that most microcontrollers are nowhere near as powerful as what we call a computer, and cannot be used to replace a computer.

The 8051 IP cores are free to use. The actual microcontrollers are incredibly cheap to buy. They are smaller and consume less power than 32 bit ARM cores. These are just some of the reasons why the 8051 is still popular.

Despite the more limited features and old architecture, the 8051 is still used in some wireless communication products. The latest HC-10 Bluetooth modules are based on 8051 core. Although 16-bit or 32-bit MCUs can replace the functions offered by 8051s, the 8-bit MCU is sufficient for many product developers.

8051 is still popular in today’s world. Current 8051 intellectual property (IP) cores use modern processor design techniques to run many times faster than the original 8051 chips. 8051 IP cores implemented in ASIC and FPGAs. Its also integrated with many smart sensors in multichip packages.

Brief History of 8051 In 1981, Intel introduced an 8-bit microcontroller called the 8051. It was referred as system on a chip because it had 128 bytes of RAM, 4K byte of on-chip ROM, two timers, one serial port, and 4 ports (8-bit wide), all on a single chip.

Intel 8051 (MCS-51) The Intel MCS-51 (commonly termed 8051) is an  internally Harvard architecture  Complex instruction set computer (CISC) Instruction set  single chip microcontroller (µC) series  developed by Intel in 1980 for use in embedded systems.

It is so called because this device comprises of transistors which are small in size (micro-meter). The word micro is used in electronics and in science generally, to mean One-millionth or 10^-6. It has also used to denote something very small like a very small processor or micro controller.

4 registers

Reset

P0 port

It is bit addressable. SM0, SM1 and SM2 are used to specify the serial connection mode. There are five different modes four are shown above in the diagram.

Embedded Systems – SFR Registers

PCON Register

ANSWER: (c) 32 12) Which operations are performed by stack pointer during its incremental phase? ANSWER: (a) Push 13) Which is the only register without internal on-chip RAM address in MCS-51? ANSWER: (b) Program Counter 14) What kind of instructions usually affect the program counter?

Explanation: If RS1=1, RS0=1, then the register bank selected is register bank 3. If RS1=0, RS0=0, then selected bank is register bank 0.

Accumulator – Generation of ALU in several arithmetic & logical operations.

4. When 8051 wakes up then 0x00 is loaded to which register? Explanation: When 8051 wakes up, Program Counter (PC) loaded with 0000H. Because of this in 8051 first opcode is stored in ROM address at 0000H.

Eddy current sensors are widely used for noncontact position, displacement, and proximity measurement. Operating on the principle of magnetic induction, these detectors can precisely measure the position of a metallic target, even through intervening nonmetallic materials such as plastics, opaque fluids, and dirt [1].

eight data lines

1.085 micro seconds

Discussion Forum

The machine cycle of a system of 11.0592 MHz is 1.085 us.

In the original 8051, one machine cycle lasts 12 oscillator periods. Therefore, to calculate the machine cycle for the 8051, we take 1/12 of the crystal frequency, then take its inverse, as shown in Example 3-13.