Generally segment register is used to store the upper. The most prominent features of a 8086 microprocessor are as follows. Unit2 8086 assembly language programming ece department microprocessors and microcontrollers page 5 to this type of instructions. Both of these first microprocessors were complete cpusonachip and had similar characteristics. Alu, control unit, instruction register, flag or status register. The term 16bit means that its arithmetic logic unit, internal registers, and most of its instructions are designed to work 16bit binary words. As technology has progressed, microprocessors have become faster, smaller and capable of doing more work per clock cycle. Status register reflects the over all operation of the coprocessor.
It was the first 16bit processor having 16bit alu, 16bit registers, internal data bus, and 16bit external data bus resulting in faster processing. The general purpose registers can be used as either 8bit registers or 16bit registers. The 8086 had eight more or less general 16bit registers including the stack pointer, but excluding the instruction pointer, flag register and segment registers. The 8086 microprocessor is a16bit, nchannel, hmos microprocessor. We say that a set of gates is logically complete if we can build any circuit without using any other kind of gates. A structure that stores a number of bits taken together as a unit is a a. Assembler directives, simple programs, procedures, and macros. The arithmetic instructions affect all the conditional code flags.
Features of 80186, 80286, 80386, 80486 and pentium family processors 18nov2009 roshan fernandes, dept of cse 1 80186 basic features the 80186 contains 16 bit data bus the internal register structure of 80186 is virtually identical to the 8086. Unlike, 8085, an 8086 microprocessor has 20bit address bus. Flag register of 8086 microprocessor geeksforgeeks. In this article, we are going to discuss the architecture of the 8086 microprocessor. The eu accesses instructions from the output end of the instruction queue and data from the generalpurpose registers or memory. The first four registers are sometimes referred to as data registers. B register structure the 8086 processor contains three.
It is the set of instructions that the microprocessor can understand. Microcomputer a computer with a microprocessor as its cpu. The 8008 processor contains two register files and four 1bit flags. Microprocessor and interfacing notes pdf mpi notes pdf.
The 8008 processor contains two register files and four 1 bit flags. The microprocessor services it by executing a subroutine called interrupt service routine isr. Register organization of 8086 intel 8086 microprocessor. Depending upon the value of result after any arithmetic and logical operation the flag bits become set 1 or reset 0. On these lines the cpu sends out the address of the memory location that is to be written to or read from.
The operands are either the registers or memory locations immediate data depending upon the addressing mode. The intel 8088, released july 1, 1979, is a slightly modified chip with an external 8bit data bus allowing the use of cheaper and fewer supporting ics, and is notable as the processor used in the original ibm pc design. Therefore, the power of the microcomputer is determined by the capabilities of the microprocessor. Flag register contains information reflecti ng the current status of a microprocessor. Where the hmos is used for highspeed metal oxide semiconductor. It is the number of bits processed in a single instruction. Microcomputer architecture, programming, and system. Registers 4 segments in 8086 code segment cs data segment ds stack segment ss extra segment es prof. The 8086 8088 does not have general purpose registers which are common in todays microprocessors and most of the registers have specific function which can only be performed with them. B register structure the 8086 processor contains three files of four 16 bit from none at university of nairobi.
These objective type 8086 microprocessor questions are very important for campus placement. The 14 registers of 8086 microprocessor are categorized into four groups. The four general purpose registers are the ax, bx, cx, and dx registers. As discussed earlier, the 8086 microprocessor consists of two main blocks. We will first see a block diagram explaining the layout of the components of the microprocessor and will then explain the diagram briefly describing each of its components. A microprocessor is an integrated circuit with all the functions of a cpu however, it cannot be used stand alone since unlike a microcontroller it has no memory or peripherals 8086 does not have a ram or rom inside it.
Intel 8086 is built on a single semiconductor chip and packaged in a 40pin ic package. Most of the registers contain datainstruction offsets within 64 kb memory segment. Introduction of registers of 8086 microprocessor youtube. Addressing modes of microprocessors and interfacing 2e, hall, 1974, computer interfaces. The major parts are the central processing unit or cpu, memory, and the input and output circuitry or io. In 1978, intel introduced the 16 bit microprocessor 8086 and 8088 in 1979. Physically, m emory is implemented as two independent 512 kbyte banks. Words will be stored in two consecutive memory locations. Accumulator register consists of two 8bit registers al and ah, which can be combined together and used as a 16 bit register ax. The address bus consists of 16, 20, 24, or more parallel signal lines. Eight of the registers are known as general purpose registers i. Al in this case contains the loworder byte of the word, and ah contains the.
An over view of 8085, architecture of 8086 microprocessor. Features of 80186, 80286, 80386, 80486 and pentium family. Description of general data registers,segment registers and pointers and index registers of intel 8086 microprocessor and brief introduction of flags. Hardware interruptthese interrupts occur as signals on the external pins of the microprocessor. Deshmukh, skncoe, comp segment segment register offset register code segment csr instruction pointer. Basic concepts of microprocessors differences between.
The register set of 8086 can be categorized into 4 different groups. Best 8086 microprocessor objective questions and answers. It has a 16bit alu with 16bit data bus and 20bit address bus. And an 8086 microprocessor is able to perform these operations with 16bit data in one cycle. The intel family of microprocessors is quite diverse.
An 8086 is interrupted by some condition produced in the 8086 by the execution of an instruction. A maskable interrupt is an interrupt that the microprocessor can ignore depending upon some predetermined upon some predetermined condition defined by status register. However, it has internal registers for storing intermediate and final results and interfaces with memory located outside it through the system bus. Registers of 8085 microprocessor a microprocessor is a multipurpose, programmable, clockdriven, register based electronic device that reads binary instructions from a storage device called memory, accepts binary data as input and processes data a.
General purpose registers in 8086 microprocessor geeksforgeeks. The intel 8086 is a 16bit microprocessor intended to be used as the cpu in a microcomputer. It determines the number of operations per second the processor can perform. It has an instruction queue, which is capable of storing six instruction bytes from the memory resulting in faster processing. An overview of 8085, architecture of 8086, microprocessor, special functions of general purpose registers, 8086 flag register and function of 8086 flags. The 8086 also called iapx 86 is a 16bit microprocessor chip designed by intel between early 1976 and june 8, 1978, when it was released. Intel 8086 microprocessor is the enhanced version of intel 8085 microprocessor. From this diagram, we see that it includes fourteen l6bit internal registers.
But because the 4004 was designed for serial bcd arithmetic while the. Generally segment register is used to store the upper 16bits of the. The registers of 8086 are categorized into 5 different groups. Unit1 introduction to 8086 ece department microprocessors and microcontrollers page 2 iv address bus. The complete 1 megabyte memory is divided into 16 logical segments. Which of the following sets are logically complete a. By nikhil kumar nirt ec 5th semester 0511ec111056 register organisation of 8086 2. Ibm selected the intel 8088 for their personal computer ibmpc. Register structure the 8008 processor contains two register files and four 1bit flags. There are 8 general purpose registers in 8086 microprocessor. It also contains informat ion which controls the operation of the microprocessor. Interrupt structure of 8086 interrupt vector table 8086. February 10, 2003 intel 8086 architecture 6 8086 instruction set architecture the 8086 is a twoaddress, register tomemory architecture.
It had an improved internal structure making it around 50% faster with a comparable. The register flies are referred to as the scratchpad and the address stack. Dear readers, welcome to 8086 microprocessor objective questions have been designed specially to get you acquainted with the nature of questions you may encounter during your job interview for the subject of 8086 microprocessor mcqs. Unlike 8085, the 8086 addresses a segmented memory. Introduction to microprocessors the microprocessor is one of the most important components of a digital computer. The flags register it is a 16bit register, also called program status. Interrupt structure of 8086 supports a special instruction, int to execute special program. Registers in 8086 microprocessor all the registers of 8086 are 16bit registers. The 8086 microprocessor has a total of fourteen registers that are accessible to the programmer. At the end of the interrupt service routine, execution is usually returned to the interrupted program. There are four segment registers such as code segment register cs, data segment register ds, extra segment register es and stack segment register ss. General 16bit registers the registers ax, bx, cx, and dx are the general 16bit registers. Pdf multiple choice questions on 8086 microprocessor.
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