Architecture and Programming model of 8086

Architecture and Programming model of 8086 Intel 8086 is a 16 bit integer processor. It has a 16-bit Data bus and a 20-bit Address bus. Since 20-bit address lines are available that provide up to 1MB of storage. It consists of a powerful instruction set which makes it possible to carry out different operations easily.It supports 2 modes of operation, Maximum (multiple processors can be used) and Minimum (Single processor is used).Architecture of 8086 The internal architecture of 8086 is divided into 2 units, Bus Interface Unit (BIU) and Execution Unit (EU).A diagram of the architecture is shown below.Bus Interface Unit (BIU)BIU takes care of all data and address transfers on the buses for the EU like sending addresses, fetching instructions from the memory, reading data from ports, writing data into the memory ports and lastly it also generates the memory addresses. The EU and the BIU are connected by the Internal Bus.The BIU has the following functional parts: Instruction Queue- the BIU uses the concept of pipelining. This means while the current instruction is being executed the BIU gets up to 6 bytes of the next instruction (prefetching) and stores them in the instruction queue. Once execution is complete, the instruction queue is ready to provide the next instruction set which is simply read and executed. This results in increased execution speed. Instruction Pointer- It is a 16-bit register used to hold the address of the next instruction to be executed. Segment Register BIU has 4 segment buses, i.e. CS, DS, SS ES. It holds the addresses of instructions and data in memory, which are used by the processor to access memory locations. CS It stands for Code Segment. It is used for addressing a memory location in the code segment of the memory, where the executable program is stored. DS It stands for Data Segment. It consists of data used by the program and is accessed in the data segment by an offset address or the content of other register that holds the offset address. SS It stands for Stack Segment. It handles memory to store data and addresses during execution. ES It stands for Extra Segment. ES is additional data segment, which is used by the string to hold the extra destination data. Execution Unit (EU)EU gives instructions to BIU stating from where to fetch data, decode it and finally execute it. Its function is to control operations on data using the instruction decoder and ALU (Arithmetic Logic Unit). The data on which the operations are performed is brought in using the BIU.The EU has the following functional parts: ALU- It handles all arithmetic and logic operations, like +, -, Ãâ€", /, OR, AND NOT. Flag Register- It is a 16-bit register that behaves like a flip-flop, i.e. it changes its status according to the result stored in the accumulator. It has 9 flags and they are divided into 2 groups Conditional Flags and Control Flags. Conditional Flags It represents the result of the last arithmetic or logic instruction executed. These flags are listed below: Carry Flag- This flag is set to ‘1’ when an addition causes a carry or a subtraction causes a borrow. Auxiliary Flag- This flag is set to ‘1’ when an addition causes a carry while moving from a lower nibble to the upper nibble in BCD addition. Parity Flag- This flag is set to ‘1’ if the low order 8 bits of the result contain an even number of ‘1’s. Zero Flag- This flag is set to 1 when the result of arithmetic or logical operation is zero. Sign Flag- This flag holds the sign of the result, i.e. when the result of the operation is negative, then the sign flag is set to 1 else set to 0. Overflow Flag- This is set to ‘1’ if the result is out of range or when the system capacity has exceeded. Conditional Flags These control the operations of the EU and can also be used by the user. These flags are listed below: Trap flag It is used for single step control and allows the user to execute one instruction at a time for debugging. If it is set, then the program can be run in a single step mode. Interrupt flag It is an interrupt enable/disable flag, i.e. used to allow/prohibit the interruption of a program. It is set to 1 for interrupt enabled condition and set to 0 for interrupt disabled condition. Direction flag It is used in string operation. As the name suggests when it is set then string bytes are accessed from the higher memory address to the lower memory address and vice-a-versa. General purpose register- There are 8 general purpose registers, i.e., AH, AL, BH, BL, CH, CL, DH, and DL. These registers can be used individually to store 8-bit data and can be used in pairs to store 16-bit data. The valid register pairs are AH and AL, BH and BL, CH and CL, and DH and DL. It is referred to the AX, BX, CX, and DX respectively. Their functionalities are listed below: AX register- It is also known as accumulator register. It is used to store operands for arithmetic operations. BX register- It is used as a base register. It is used to store the starting base address of the memory area within the data segment. CX register- It is referred to as counter. It is used in loop instruction to store the loop counter. DX register- This register is used to hold I/O port address for I/O instruction. Stack Pointer Register- It is a 16-bit register which holds the address from the start of the segment to the memory location, where a word was most recently stored on the stack.

Change Project Essay Example | Topics and Well Written Essays - 250 words

Change Project - Essay Example Emotion or  affect  is the  method  in humanistic psychology that recognizes feelings and the  consideration  that results to transformations in performance and  cognition. A person realizes the need to change when something happens. This is a practical  proof  that works for individuals, healthy  family  growth  and couples. There are several behavioral forms. Change of behavior  is widely investigated  and  is applied  for parenting method. A person should  cease  the behavior and begin to work directly on  transformation. Regarding thoughts  technique, there should be  motivation  that originates from the inside because the  secret  to  achievement  is within each and  everyone. If a person has  positive  faith and  devotion  to what they do,  subsequently  things work out in a positive way. In system technique, a person needs to be  optimistic  to  attain  what he wants. Support from family is  essential  for a persons’  achievement  because  system  change involves the whole system and not just an  individual. Culture plays a crucial role when initiating change. Working against  predominant  customs will make attaining  transformation  harder, but working with it and identifying fundamental forces can  aid  ease  change. Reaction to  modification  when change  is forced  is  constantly  difficult  (Whitbourne, 2010).Reference Whitbourne, S. K. (2010). Beginnings: Psychological Perspectives on Four Types of Change. Retrieved October 19, 2011, from Psychology Today:

Politic papers Essay Example | Topics and Well Written Essays - 1750 words

Politic papers - Essay Example Wars have raged in these regions for several years and the devastation brought about these wars has been tremendous. To be specific, the Iraq War had cost so much destruction of lives and properties. For the next five years, the destruction of lives and properties will most likely continue. On the other hand, the aftermath of the war could take a great toll on the economy and stability of the area for the next 20 years. The implications of the war in Iraq on the lives of the people and the security of the area are so great that the United States should address this problem more fully. I fully understand the position of the United States on the issue of terrorism but the point is that there are other ways of address terrorism other than counter-violence. We all know that violence begets violence and if the United States does not take concrete moves to end the violence in the area once and for all, this situation will not be resolved in the next several years. I believe that a solution of the problem would be a shift in foreign policies in Iraq. Instead of focusing on counter-terrorism and supporting the armed conflict in the area, the United States government should focus its attention more on the rehabilitation and rebuilding of Iraq through education, economic development and political participation by the people. We must understand that as long as the people in the area feel oppressed and deprived, they will be more prone to violence. Due to the presence of oil in this region, most of us are lead to believe that the economy in these parts of world is doing well. Unfortunately, that is not the case. Although some of the oil rich countries in these areas are dong really well, many of them are struggling to against poverty and deprivation. According to the report of the World Bank in 2006, about one in every five persons in the Middle East and North Africa Region can be