in this video we are going to discuss about architecture of eight zero eight six microprocessor or this can also be called as our block diagram of 8086 microprocessor okay so this is nothing but architecture of 8086 microprocessor or we can call this as block diagram of 8086 microprocessor here a086 microprocessor is a 16 bit processor so 16 bit processor means 8086 microprocessor performs operations on 16-bit data in one clock cycle so here the data bus size is 16 bits whereas size of the address bus is 20 bits so 8086 microprocessor has 16 bit data bus and 20 bit address bus so the size of the physical address is 20 bits okay uh now let us see this diagram so this anti diagram so this entire diagram so that the this dashes the diagram which is placed in this dashes is called as what architecture of the 8086 microprocessor here this architecture is mainly divided into two parts the first part is called as biu the second part is called as eu biu means bus interface unit so biu stands for bus interface unit bus interface unit whereas what is the second part the second part is eu eu stands for execution unit execution unit so here this part this part is called as biu okay this part is called as biu so bus interface unit mainly contains resistance these resistors are called a segment resistance and this is nothing but adder circuit and instruction queue so bus bus interface unit mainly contains three things what is the first one segmentation register so all these resistors are called as segmentation resistance and this is called as adder circuit and this diagram is nothing but instruction queue whereas this part this down part is called as execution unit execution unit mainly contains control system and a bus arithmetic logic unit operands flags these resistors are called as general purpose registers these resistors are called as offset resistance so execution unit mainly contains these strings so general purpose resistance offset resistance arithmetic logic unit operands flags control system so this is nothing but what does an execution unit will contain and then let's see the advantage of the bus interface unit bus interface unit mainly fetches an instruction from the memory so here outside the processor we have memory so memory is not the part of the processor so on top of the processor we have memory so processor interacts with the memory so here bus interface unit fetches your instruction from the memory bus interface unit reads an instruction from the memory and then stores the corresponding instruction in instruction queue with the help of the bus we know what is a bus bus contains a set of lines through which the information is passed so bus interface unit fetches an instruction from the memory and stores the corresponding instruction in instruction queue here the size of the instruction queue is 6 bytes six bytes so totally instruction queue can stores six bytes of instructions there may be of same instructions or the instructions may be from different instructions but here totally we can store six instructions in the instruction queue here this is nothing but q we know that q works on fifo policy first in first out policy first instruction first out policy let us assume that biu fetches the first instruction the first instruction is stored here and then it fetches second instruction second instruction is stored here followed by three four five six okay so while retrieving also first instruction will be reviewed first okay because this is first in first out so first instruction will be executed first second instruction will be executed first third instruction will be executed next likewise so first instruction second instruction third four five six likewise the instructions will be executed one by one now let us see about segmentation registers so all these resistors are called as segmentation registers so let us see about segmentation by using with this diagram so this diagram is not a part of the architecture so simply for explaining segmentation concept just i am taking the help of this diagram okay so this is not the part of 8086 microprocessor this is nothing but memory main memory that main memory is divided into four parts four segments here this starting address this is nothing but code segment and this segment is nothing but stack segment this segment is nothing but data segment and the last segment is nothing but extra segment okay code segment is nothing but it points to the starting address of the first segment stack segment points to the starting address of this the segment data segment points to the starting address of the segment extra segment points to the starting address of this segment okay core segment mainly contains the program which is executed whereas stack segment contains subroutines functions all the functions are nothing but subroutines subroutines are located in stack segment and data segment and extra segment contains data on which we are performing the operation add a comma b a and b contain some data so this those data will be stored in data segment and extra segment okay here we have the first register yes cs ca stands for code segment resistor here all the resistors size is 16 bits all the register size is 16 bits why because why because 8086 microprocessor is a 16-bit microprocessor it performs operations on the 16-bit data so that's why the size of the each register is 16 bits so the first register is cs cs stands for code segment register the second register is the ss ss stands for stack segment resistor third register is ds ds stands for data segment register fourth one is es ea stands for extra segment register and the last one is ip ip stands for instruction pointer it specifies the offset okay we will discuss that here only so here we have ip ip means instruction pointer let us first let us see about what is cs ces resistor contains starting address of the code segment let the core segment address is thousand the thousand will be stored in cs next stack segment register contains starting address of the essay segment let the stack segment address is 2000 the 2000 will be stored in ss register we know that resistors are useful for holding the data here we are storing the addresses data ds stands for data segment register it contains the address of starting address of this ds segment likewise extra segment register contains starting address of yes here ces ssds esr segments various all these are resistance so these resistance contains addresses of these signals okay next here if you observe here here these four are called as offset resistors these four are called as offset resistors offset resistor means a particular location in that segment so sp means stack pointer so stack pointer points to the offset of stack segment so a particular location of the stack segment okay next one bp bp stands for base pointer base pointer also points to the address of some segment here next one is s i s a stands for source index source index points to the offset of the data segment destination index points to the offset of the extra segment extra segment segment likewise we can we can also use bp as offset to extra segment and data segment also okay so this is about resistors and corresponding instruction pointer now let us see about yadder this is called as the other here we are using the adder in order to calculate the physical address so what is the physical address the processor generated address is called as physical address okay whereas the address of hard disk is called as logical address so now we have to find out the physical address okay in order to calculate the physical address here we need two things the first address is segment address variance the second address is offset address so the formula for the physical address is physical address is equal to segment address into 10 plus offset so what is the formula for physical address physical address is equal to segment address into 10 plus offset let us assume that here we are finding the physical address for the code segment so code segment means this one let the address of the code segment is 1000 let ip what is ip ip means instruction pointer it points to the offset unless it is a thousand next instruction address is thousand one next thousand to next thousand three likewise we have several instructions here let us assume that ip means two three four five instruction pointer is two three four five we need to execute two thousand three forty five line okay so how to calculate the physical address physical address is equal to segment address into 10 here the segment is nothing but core segment what is the address of the code segment 1000 so 1000 h 1000 h address address is specified with the help of h so thousand into ten means ten thousand so ten thousand plus what is the offset here two three four five so ten thousand plus two three four five means twelve thousand three forty five so twelve thousand three forty five is nothing but physical address here we in order to calculate the physical address we are we are using this adder so we are using this adder for calculating the physical address so this is about biu bus interface unit so bus interface unit fetches an instruction from the memory and stores the corresponding instruction in the instruction queue now let us see about the duty of the the functionalities of the eu execution unit execution unit retrieves your instruction from the instruction queue and then with the help of the control system it decodes the instruction so execution unit first retrieves the instruction from the instruction queue so first it retrieves the first instruction from the instruction queue and what the control system will do this is nothing but here this control system is nothing but the part of the execution execution in it control system decodes the instruction decoding means it determines what is the type of the instruction whether it has to perform yard instruction or sub instruction or some logical instruction or shift instruction it decodes the instruction it determines the type of the instruction that is to be performed okay control system will do that thing and then what the control system will do is with the help of the bus that information that uh that is to be performed let it be add operation so that information will be transmitted to the these resistors as well as arithmetic logic unit okay with the help of the bus those things will be passed to registers as well as alu now let us see about resistors here a h a l b h b l c h c l d h d l all these resistors are called as general purpose registers all these resistors are called as general purpose registers general purpose resistors general purpose resistors are useful for temporary calculations here a h means a means accumulator b means base c means count various d means data a stands for accumulated b stands for base c stands for count various d stands for data here each register size is 16 bits so the size of the ah is 8 bits the size of the al is 8 bits so 8 plus 8 means 16 bits the combination of a h and a l is called as ax the size of the ax is 16 bits here the processor can perform operations on eight bit data also okay next the combination of bh and bl is called as bh ch and cl is called a ch bh and dl is called as dx so a x b x c x d x these four are called as general purpose registers they are useful for some temporary calculations so in order to do in order to store that result we use just the general purpose registers okay here h stands for higher order so higher order bits whereas l stands for lower order bit so accumulator higher order bits next accumulator lower order bits next base resistor higher order bits based register lower order bits next to count register higher order bits next to count register lower order bits here bhbl capacity is 88 888 okay here the accumulator here the first register is called as accumulator accumulator is called as default register why because here in order to perform the operations we are using arithmetic logic unit in short we can call you as a anu alu is the brain of the cpu alu performs any operation it may be arithmetic operation or logical operation or shift operation data transfer manipulation program control instructions likewise plenty of instructions are there any instruction is executed in the cpu in the processor with the help of alu only alu performs the operation on two operands where the first operand is from accumulator only whereas the second operand is from some other resistor so that's why this is called as default resistor why because accumulator performs operations mainly on two resistors or three resistors or four resistors but in those resistors one resistor must be from one operand must be from accumulator resistor whereas the remaining things from maybe from operands maybe from the remaining resistance okay so that's why we can call accumulator as a default register so what does ailu will do now alu will accepts the data from the corresponding resistance let the instruction is like this add add a h comma a l let the content of the ah is 123 let the content of a l is 122 okay now what the alu will do alu will yeah the content of a h and a l and the corresponding result will be stored in a h only so what is the result of 123 plus 122 so 240 245 so that is the result okay so that result that result will be stored in the bus and again the bus will will pass us that information to the segmentation register segmentation register passes that add that that result to the adder the adder will pass us the result to the memory memory okay so what is the result here 245 so execution unit executes the corresponding instruction and after that with the help of the bus execution unit passes that information to the biu bus interface unit bus interface unit will in turn passes that information to the memory so that information will be stored in the memory now here we have operands and flags let us assume that some data is in the operand so processor can accept the data from the operand and it performs the corresponding operation okay so instead of accepting the data from a l it may take data from the operand let the data is 10 so directly data will be taken from the operand operand field next year we have flags so sometimes flags maybe flag bit may be affected we have different types of flags are there carry flag parity flag overflow flag interrupt enable flag likewise several flags are there we will discuss more about flags in the flags concept in the next video so if they if there is any flag bit affected so that flag bit will also be uh passive to the bus so from the bus it will be transmitted to memory also okay so this is about bus interface unit and execution unit so bus interface unit mainly fetches the instruction whereas execution unit executes the instruction after execution it passes the result to the bus interface unit bus interface unit in turn stores that information in information in memory so why the architecture why the microprocessor architecture is divided into two parts so why we have two parts here we are here we have divided the architecture into two parts in order to implement a concept called pipelining pipelining eight zero eight five microprocessor doesn't supports pipelining whereas 8086 microprocessor supports pipelining so what is pipelining while execution unit is executing first instruction while execution unit is executing first instruction then in the mean time bus interface unit bus interface unit fetches the second instruction it fetches the second instruction third instruction fourth instruction up to five instructions it will fetch up to six instructions it will fetch so here what is happening execution unit is executing the first instruction and in the mean time bus interface unit bus interface unit is not sitting ideal it is fetching the remaining instructions from the memory so we can speed up the processing in less amount of time we can execute the instructions whereas if you take eight zero eight five microprocessor in eight zero eight five microprocessor what will happen is first instruction one will be fetched and then instruction one will be executed and after that after complete execution of the first instruction second instruction will be fetched second instruction will be executed after the complete execution of the second instruction then only third instruction will be fetched third instruction will be executed but here that problem is doesn't arise is here while the while the execution unit is executing the first instruction biu can fetches the remaining instructions from the memory so here the time is lost not wasted so in lesser amount of time the processor can execute more number of instructions so that is the reason why this architecture is divided into two parts in order to implement pipelining concept okay so here everything is explained so stack pointer we have base pointed source index destination index here all these are nothing but offset resistors okay here stack pointer base pointer instruction pointer these three are called as pointer resistors pointer resistors whereas source index and destination index are called as index registers we will discuss some more points on the resistors in the next concept that is resistor organization so this is about architecture of 8086 microprocessor or block diagram of 8086 microprocessor so this is about architecture of 8086 microprocessor