Microprocessors and Interfacing

The programming model for a microprocessor shows the various internal registers that are accessible to the programmer.   The Following Figure is a model for the 8086. In general, each register has a special function. In the programming model there are -           4 General Purpose registers( Data Registers) -           4 Segment registers -           2 Pointer registers -           2 Index registers -           1 Instruction Pointer register -           1 Flag register General purpose registers: AX Register (Accumulator):  This is accumulator register. It gets used in arithmetic, logic and data transfer instructions. In manipulation and division, one of the numbers involved must be in AX or AL. BX Register (Base Register):  This is base register. BX register is an address register. It usually contain a data pointer used for based, based indexed or register indirect addressing. CX Register (Counter register):  This is Count register. This serves as a loop co

  8086 fetches instructions and data from memory. The process of instruction execution is as follows. - The BIU outputs the contents of the instruction pointer register (IP) onto the address bus, causing the selected byte or word to be read into the BIU. -   Register IP is incremented by 1 to prepare for the next instruction fetch. -   Once inside the BIU, the instruction is passed to the queue. -   Assuming that the queue is initially empty, the EU immediately draws this instruction from the queue and begins execution. -           While the EU is executing this instruction, the BIU proceeds to fetch a new instruction. -           Depending on the execution time of the first instruction, the BIU may fill the queue with several new instructions before the EU is ready to draw its next instruction. -           The BIU is programmed to fetch a new instruction whenever the queue has room for two additional bytes. There are three conditions that will cause the EU to enter a

a)      The 8086 microprocessor is a 16 bit microprocessor.   The term “16 bit” means that its arithmetic logic unit, internal registers and most of its instructions are designed to work with 16 bit binary words. b)        The 8086 microprocessor has a 16 bit data bus. It can read data from or write data to memory or ports either 16 bits or 8 bits at a time. c)         The 8086 microprocessor has a 20 bit address bus, so it can directly access 220 or 1,048,576 (1M) locations. d)      The 8086 microprocessor can generate 16 bit I/O address; hence it can access 216 or 65536 ports. e)      It is possible to perform bit, byte, word, and block operations in the 8086 microprocessor. It performs the arithmetic and logical operations on bit, byte, word and decimal numbers including multiplication and division. f)        The 8086 microprocessor is designed to operate in two modes, the minimum mode and the maximum mode. When only one CPU is used in the system, the 8086 mic

1. In 8051 what are special function registers? Name any four SFRs. 2. Explain on-chip RAM structure of 8051. 3. Draw and explain the architecture of 8051. 4. What is the difference between timer and counter? 5. Differentiate between microprocessor and microcontroller? 6. What is a microcontroller? Mention few applications of it. 7. What is the difference between LJMP, AJMP and SJMP? 8. Explain about following pins. (1) EA’   (2)   PSEN’   (3) ALE 9. What are alternate functions of Port-3 ? 10. Explain about structure of four ports with neat diagrams. 11. Explain about different modes of operation of timer. 12. Write a program to generate 1KHz waveform on P1.7 (Assume XTAL = 11.0592MHz) using timer-0 13. Write a program to generate two waveforms with 5KHz and 25KHz simultaneously on P1.7 and P2.7 respectively.(Assume XTAL=22MHz). Use interrupt method. 14. Write a program to find number of zeros in register R6. 15. Write a program to complement lower nibbl