8051 Microcontroller

Comparison of 8051 with the well known Pentium processor A quick comparison of 8051 with the well known Pentium processor A modern PC is powered by a Pentium processor (or equivalent), which is really a very powerful microprocessor. Where the 8051 microcontroller represents the low end of the market in terms of processing power, the Pentium processor is one of the most complex processors in the world. Figure 1.3 shows a simplified block diagram of the Pentium processor and a simple comparison between the 8051 and the Pentium is given in the table below. FEATURE 8051 PENTIUM COMMENT Clock Speed 12Mhz.  typical but 60MHz. ICs available 1,000 MHz. (1GHz.) 8051 internally divides clock by 12 so for 12MHz. clock effective clock rate is just 1MHz. Address bus 16 bits 32 bits 8051 can address 2 16 , or 64Kbytes of memory. Pentium can address 2 32 , or 4 GigaBytes of memory. Data bus 8 bits 64 bits Pentium’s wide bus allows very fast...

8051 reset circuit.  The 8051 has an active high reset input must 0 high for two machine cycle when power is first applied and then goes to low. The simple RC circuit used to supply system voltage(VCC) to the reset pin until the capacitor charge. At a threshold of about 2.5v, the reset input reaches a low level and the system begins to run. The reset button enables the user to reset the system with out having to turn power off and on. 8051, 8051 reset circuit, clock circuit of 8051., mazidi, microcontroller 8051 basics, 

Block diagram and pin diagram of 8051 microcontroller with description. ALU: Arithmetic & Logical Unit (ALU) is capable of opertating on byte level and bit level.ALU performs arithmetic functions like addition,subtraction,multiplication and division.It is also capable of performing logical functions normally called Boolean functions. Register A: The register A is also called as accumulator.It is Used for many Operations,particularly mathematical and logical operations,and Boolean bit manipulations.The register A is also used for all data transfers between the 8051 and any external memory. Register B: The register B is used with the A register for multiplication and division operations and has no other function than data storage. Program Counter(PC):             The 8051 contain a 16-bit register called as Program Counter,which is used to hold the address of a byte in program memory.The PC is automatically incremented after every instructi...

Clock circuit of 8051 The 8051 has on chip oscillator pin XTAL1 and XTAL2 are provided for connecting a resonant network to from an oscillator crystal frequency ranges from 1 MHZ to 24 MHZ. Ceramic resonators may be used as a low-cost alternative to crystal resonators but due to decrease in frequency stability and accuracy, ceramic resonators are not preferred for high-speed serial data communication with other system. The oscillator formed by the crystal, capacitors, and on chip inverter generates pulse train at the frequency of the crystal as shown in fig. The clock frequency & establishes the smallest interval of time within the microcontroller, called the pulse, p, time. The smallest interval of time to accomplish any simple instruction, or part of a complex instruction, however, is the machine cycle. The machine cycle is made up of six states. A state is the basic time interval for discrete operations of the microcontroller such as fetching on encode byte decodin...