hi everyone architectural operating systems we are in week 14 and in this video i'm going to explain more about is computer which i introduced in the previous pick so what we did last week was uh talking about the computer architecture and computer organization computer architectures talks about those attributes that have a direct impact on the logical execution of the program and computer architecture refers to operational units and their interconnection that realize the architectural operation so as you see here for example these two cars have got the same architecture the logical design of them but in terms of the interconnection and the components they are different so to come to architecture it talks about the logical execution organization talks about how the different parts are interconnected then we discuss about the computer functions the main four functions and three levels of computer structure and also we talked about van neumann architecture or ias machine the computer functions that we discussed was data processing data storage data movement and data control and we discussed that for data movement data processing and data storage we need to have this control mechanism at the heart of this orchestra also we discussed the computer structure in three layers in the top layers you've got input output device like printer keyboard screen we've got main memory cpu and we've got interconnection tool system between them which we call them bosses system boss that send and receive the data between these three parts and also we looked at inside the cpu and i showed you that we've got alu which is called arithmetic logic unit something that we discussed in first teaching block how to create a circuit how computer works based on binary numbers we've got registers that i'm going to explain today we've got control unit that controls all the operations sending the signals and also they've got internal bosses which send and receive the data between these three elements inside the cpu so we discussed about distort program concept in van neumann architecture or ias machine in the inioc the first machine that was developed in 1946 they used wired and vacuum tubes to program it means that manually they put these logical gates let's say together they create a circuit that we did in the first stitching block for example for adding two numbers they did that one manually and then they loaded it by the data and got the results but it wasn't quick enough it wasn't efficient and van noiman in ies machine proposed something new that they can store both data and instruction which means the program on the machine the task of entering and altering programs for enoch was extremely tedious but suppose a program could be represented in a form suitable for storing in memory alongside data then a computer could could get the instructions by reading them from the memory and a program could be set or altered by setting the values of a portion of a memory so that was the main difference between ios machine and the one developed before so that could store both program and data on the machine this is the proposal or architecture of iis machine that it's got four parts main memory input output devices alu arithmetic logic unit alu and control unit this call this is called cpu and in this machine this architecture we store both program and data on the memory we do the operations in alu we know how that happens we know uh actually logical circuit we know optimization to actually make a very efficient operation and it's this part program controlling it controls how that works and the rest and also we know that we can get the data from input devices like keyboard and output like printer for example so this is the architecture of the is machine that even today we are using the same architecture but with different organization and different components in this machine is via store i said that it's a store program concept it means that we store both data and instruction on the machine on the memory so what how is the memory in the is machine they had 1 000 locations in the memory 1000 location both for data as you see 39 bits for the number one bit for the sign we know that very well from the first teaching block and then we've got words or four tip bits for instructions in each instruction in this machine they have two one left action instruction and right instruction in each part in each instruction we've got op code and address what it means for example we want to say store to add two numbers for example you write a program x equal to y equal five z equal x plus y x equal to we'll go and see here in one of the word it's addressable it's got a location for example in location one you store x in location two or five ten whatever you store the second number which is five so next one you've got to add numbers what number for example number one with number five i mean the location one location five so we've got to give the address this is the program that you write you've got to have address and also we've got to tell the machine that you've got to add them we use opcode 8 bits to show that to say that okay now we want you to add these two numbers so the op code that i'll show you the list of the is up codes 21 actually upgrades that what happens so the computer gets these up codes interpret that and then execute this so they've got two types of words number words and instruction word in uh ias machine so here venom in architecture i said that we send receive data between them but we need temporary storage between each of these between every two of these machines even between these two we've got some direct links but they should have capability of restoring parts or storing bits let's say so what's up called the car register so registers or the temporary storage between here inside the cpu that they can store the data temporarily between different components of this architecture we've got several type of storage registers nowadays very quick memories they are but here i just tell you the most important font that are used for ias machine so this is our is architecture we've got input output this is the main memory this is the alu and this is our program control unit here as you see here guys they are or register pcma or ir i b or mbr all of them are registered they are temporary writable memories the first one is memory buffer register as you see memory buffer registered send and receive the data to the input output equipment it send and receive data from main memory there is a link between them you can write on the memory from here and you can read from here it's a buffer and also it said when he gets it but it gets an instruction it send the instruction to the cpu and then it gets it then there is a data here it send it to the alu because it's a store program concept machine so we've got both data and um instruction so what happens send both data and instruction data here instruction to the cp the first one is memory the second is memory address register imagine that we read the data which is um an instruction goes to the mbr in mbr it realized that that's instruction so it send it to the cpu to understand what it is as i showed you here each instruction has got address and up code so this mar specifies the address inside the memory the next one is ir it uh it's actually decode the up code so we break the instruction here into address and op code address goes and specifies the address that you want inside the memory up code understand what it is and send it to the control circuit to send the signal to the alu i will explain that in more details instruction buff register is here usually in is machine they use the left instruction but if they got a right instruction here the right instruction will go to the ibr and then the op code will go to the ir and the address will go to mar so instruction buffer as you said it's a buffer for instruction for the right instructions on the 40 bits word and program counter specifies the next instruction that should be fetched or or executed that should be read or should be done so it shows the next line of the program that should be done accumulator and multiple questions here then are actually an operation is undertaken in alu in a circuit so the 14 most significant bits will go inside the ac and the 40 less significant bits goes to mq generally speaking the result will go and save here and then they can be stored on the memory or then can go to present as an output so these are the most important registers that they have how computers use them in two cycles fetch cycle and execute circuit in the fetch cycle or reading cycle we read the instruction it means that we start because the computer works line by line in the memory it is start reading from for example a specific place like 250 start reading and going down line by line in the sequential fashion so first of all we read in the reading cycle we call it fetch circuit we read it we read the instruction go to mbr then send it to the mar and ir the address will go to mar the op code will sit in ir this is called reading cycle or fixed circuit in execute cycle we understand what op code is and then we start doing that operation adding subtracting whatever so when the ir gets the op code it goes and to the interpreter and it's been it's been interpreted and send the right signal for example the opcode is for adding two numbers sen actually goes to the control circuit in interpreter here and we said okay now send a signal to alu you've got to add these two numbers that are coming you've got to subtract it it depends on the outcome what numbers mar will tell us where to go and find that so mar sorry fetch circuit talks about reading execute is about executing computer works in first execute cycle and all the operations happens yeah of course that i told you look 21 up codes exist in a ias machine for example adding two numbers zero zero zero zero zero one zero one it's about adding add mx to ac and this description and this is the symbol for that subtract zero zero one one zero multiplication one zero one one as you see we have 21 up codes here that ias machine used to do the operations so this is is machine we've got three main concepts which are very important first of all single read write memory we can both read and write data and instruction on the memory it's a stored program concept the memory is addressable it's very important because we should know where to store the data where they read the instruction from and execution occurs in a sequential fashion from one instruction to the other one so when you write a program for example your program starts from the location 125 100 2500 26 127 so it goes line by line in the memory and goes down in a sequential fashion unless explicitly modify for example an intro puppets we'll discuss that later so these are the most important or key concepts in the ias machine or random man architecture two things first of all programming in hardware in anyak what happened that i said that they used hardware they used voyer hard hardware to actually create arithmetic logic unit or function for example we did that using logically create a circuit so we used programming in hardware so you create your circuit manually by hand then load the data and you get the result so what we did in the first glock was all about programming in hardware because manually we created the circuit this is not happen this is not efficient in the store program concept oh i'll tell you but look this is a circuit for example that students designed for a burger or arm system so using logically put all these gates together to be able to create a very armed system the other one the picture is a actual hardware pro a hard programming hardware or hardware and you actually tool that they use for programming but programming is software is different what happens i said that each instruction has got an upgrade to opcode it goes to the control circuit or inter instruction interpreter so it goes and read it from the table okay this op code is for adding it into it's interpreted here and then send the control signal to the general purpose arithmetic and logic unit imagine that i want to add two numbers i've got a single other subtractor circuit when you want to add so you've got a specific up code for adding so the instruction interpreter understand that's the adding send the signal to the general purpose other substrate that we have that okay this is idea this is adding operation you need to turn the external switch off so that happens and then you get the data from the memory because you can both store the data instruction on the memory from the memory and then load it with the data you get the results if you want to subtract two numbers the instructor op code is about subtraction so use the instruction interpreter understand that says subtraction send the signal to the general purpose other subtractor that we have and says okay now based on this this is the signal and you need to turn the external switch on the one that we have i'll show you in other subtractor when you turn that external switch on it means that you've got to you have subtraction so then you know the data and you get the result so inside the alu what happens is that we've got a general purpose arithmetic logic functions and based on the signals that we get from the instruction interpreter we actually form a new circuit the one that we want to use inside the machine this is called programming in software the opcode comes interpreted send the signal to frame the alu to create the right circuit for us and then load the data and get the results this is called programming in software that what you are doing on our machines so where does it go it is here interpreter and all of them will sit here the instruction and the data sits on the memory so we get them from here interpret that send the signal to here and then oops and then give the result back to input output device so this is how computer works in ias architecture top level view of that we've got the cpu and sorry we've got the cpu with all the right registers that we have and also we've got execution units or alu that we discussed we've got input output modules we've got different we've got buffers here we've got places here ports for example you've got different ports for uh printer for monitor for whatever we've got main memory which is addressable as you see from zero till the last one for iis we've got 1000 location we've stopped both instruction and data we know that instructions can be interpreted by the interpreter and send the signal to the execution unit between these three units what we have is system boss that will discuss that later inside the cpu we've got internal posts that again will discuss it so this is the top level view of the computer components in ios machine chapter 23 if you want to read that it's available on the library you can borrow that next week instruction fetch and execute i'll go in more details of how exactly computer works thank you much guys