Pin Diagram – 8085 Microprocessor – Microprocessor

Pin Diagram – 8085 Microprocessor – Microprocessor


Hello Friends, In this video We are going to study about the pin diagram of eight zero eight five Microprocessor So let us first draw the pin diagram of a eight zero eight five. As eight zero eight five it is a 40 pin, IC so there are 40 pins in it. Starting from 1 to 40 we will start from 1 to 3 till 20 and 21 will start from here, so this in this way we have the numbering of the pins Now 21 we’ll start from here So this was the for tipping I see now This Name all the pins that put these pins are representing the first and the second pin They are X 1 and X 2 Then third pin let us first draw then we will study over one bag on all the pins what they are represented So this is the pin diagram of a 0 8 5 the first and the second pin are X 1 and X 2 Third pin is reset out for so s OD + v this aside in 6 we have trap rst 7.5 rst 6.5 rst 5.5 int are int a bar then LD not 81 82 83 84 85 86 87 These are the address and the data buses multiplexed with each other then we have V s s a8 a9 10 a 15 the higher order address bus s not LD WR bar Rd bar is one I not an M bar that is input output and memory operation ready reset in clock out h lda hold and VCC, so these are the 40 pins representing various signals of the 8 0 8 5 Now we will study each of the pins one by one so first the pin 1 2 and 37 these three pins they are related to the clock pulse of the 8 0 8 5 x1 and x2 the crystal which is providing the clock frequency to the 8 0 8 5 These are the two connections of the crystal X 1 and X 2 and the output or the? Clock frequency clock pulse it is provided at the 37th pin that is that is written here clock out from here the clock pulse will be given to the 8 0 8 5 So we have pin 1 2 and 37 So the clock frequency at which the 8:08 five books it is three megahertz Approximately it is three megahertz so this 8:08 five it is a specifying limits on the clock frequency the minimum frequency is 500 kilohertz and the maximum frequency is three point one two five Megahertz now, let’s see the connections of the crystal at pin one and do So the crystal which is generating this clock frequency the crystal is connected at pin 1 into This is one in two and this is our crystal It’s connections are X 1 and X 2 now this internal structure of this pin 1 & 2 is like here We have an inverter and this inverter is providing the signal to the JK flip-flop And this flow it produces two outputs one is 5 and second is Phi 2 Phi 1 is Representing the clock pulse, and Phi 2 is representing the reverse of it suppose here. We are getting 1 then It will give us 0 and this output clock pulse It is given to the thirty-seventh pin so this pin is mark as clock Now this flip-flop it will divide the frequency of the crystal by 2 so here we are using the crystal of frequency six megahertz and This JK flip-flop it is going to divide it by 2, so We have flip-flop Divides the crystal frequency by two so we have the crystal frequency In the range from one to six point two five megahertz So when the flip-flop it is dividing it into two so we are getting the output as 0 We are getting the output as 500 kilo Hertz to three point one two five megahertz and These are the capacitors connected here and these capacitors are of the range ten to twenty Pico farad’s And the clock signal which is coming out of the pin 37 it is used to drive the peripheral chips Peripheral means the input/output devices so the input/output devices connect to it to the eight zero eight five they are drive using this clock pulse Next in the pin diagram it comes pin number three so pin number three is Next we have the pin number three so this pin three in The pin diagram it shows the three set out This pin number three is showing the signal we set out It is an active high signal It means that if there is active and its value is equals to one so when this reset out signal it is high it indicates that the Microprocessor it has been reset so all its conditions all the resistors They are bring back to the position zero and all the flag registers They are also again reset so all the components and the register they are being Bring back to their original Conditions initial conditions. They are bring back so when reset out is high So when the signal is high it indicates that the microprocessor is being reset that is all the registers and the flagged register program counter instruction register all are being reset to Zero, so it has bring it to the initial conditions now when you first start the microprocessor then the whole system including the microprocessor CPU ALU unit have the control unit all the chips of the eight zero eight five they are in the reset conditions now while processing if you want to again bring back the microprocessor to its initial conditions Then just press the switch or reset out signal And then the microprocessor is again bring back to its initial conditions So when you first start up the microprocessor the 8 0 8 5 is CD set or Initialized and this reset out signal is high and when this reset out signal It comes to know that its value becomes 0 then the processing of the CPU starts so if you want to start the processing of CPU this reset out signal should be low and then it is high the Microprocessor is in the reset condition Now next in the pin diagram We have the pin number 4 and 5 these are the SID and the sword signal So let’s study about pin number 4 & 5 Sit and saw The full form of these signals are serial input data and serial output data These two signals are used in when the microprocessor is used in the serial input output communication So when this signal is high it means that the serial the data Which is available? It is an input data, and when this signal is high. It means the data. Available is the output data Next we have pin number 6 – pin number 11 From pin number 6 it Is trap then we have rst seven point five six point five five point five and I dri NBA These signals from pin number six to eleven. They are used in the interrupt process of the a zero eight five So for the interrupt controlling these pins are used Trap rst. Seven point five two are sto five point five and int e these are the interrupts various types of interest trap and restart signals and int R Is the interrupt request and int a is the interrupt acknowledge signal? This int a bar it is our active low signal int R is an active high signal these signals We are going to study, and we will study about the interrupts process of eight zero eight five So these things are used for the interrupt control unit six to ten pins They are the input pins for the interrupts and pin eleven is an output signal called the interrupt acknowledge signal which is an active low signal and it is active when its value is equal to 0 Then we have pin number 12 – pin number 19 from pin number 22 pin number 19 We have the address and the data bus the lower order address bus multiplex with the data bus In about twelve to nineteen Next we have pin number 20 Pin number 20 is VSS that is ground so when the voltage supply the five volts power supply Is connected to 8 0 8 5 then this ground is connected to pin number? 20 and the positive sub-point is connected to pin number 14 so pin number 20 is the system ground Pin Then we have pin number 21 to pin number 28 21 to 28 we have the higher order address bus Starting from a 8 to a 15 and the lower order address bus it was present at pin number 12 – 19 Multiplexed with dateable so it is represented as ad not to a d7 These are the eight bits and these are the eight bits combined reforming the sixteen bits of the address bus now pin number twenty nine and We have pin number 33 On pin number 29 we have s not and on pin number 33. We have s1 This s1 is not these are the status signals These status signals define that what type of operation is being performed by the microprocessor so this is not an s-1 It can be 0 0 0 1 1 0 and 1 1 So when s not an s-1 they both are 0 then It is a halt to state when s naught is 0 s 1 is 1 it is read right and fetch So the status of these signals Zero zero zero one it is defining that what type of operation microprocessor is performing whether it is reading writing or fetching an instruction Or it is at hold is stable. Okay, that is for the state. It is not performing any of the operations right now Then we have pin number Forty Pin number thirty is a li a remains address latch enable This signal it is an active high signal And it is used when we want to be multiplex the address and the lower Data, bus we have the address and data bus multiplex like a Dino 287 so when we want to separate it out that we want a not to a seven and we want D not to d7 Then this address latch enable is used when the signal is high it means that on this Bus the data, which is available it is the address of a memory location or an input device So whenever this is high it means that addresses are available on these lines ad not 287 then we have pin number 31 32 and 34 Pin number 31 is right 32 is read and 34 is input output and memory operation Rd bar means that the microprocessor is performing the read operation WR bar means it is performing the right operation and input/output, I hope means it is an input-output operation and M bar means it is a memory operation So the microprocessor it will either perform the read operation of the memory or the Input/output, or it is it will perform the right operation on the memory or the input/output input/output it is an active high signal an M bar WR bar and RD bar These are the active low signals so when this line i/o and M bar it is high it means that The input/output operation is being performed and when it is low it means a memory operation is being performed Next comes the pin number 35 pin number 35 is ready pin. Okay, so we have Pin number 35 it is ready signal This ready signal it is an active high signal Sometimes we have to connect the microprocessor to various types of Devices and the working of the microprocessor it can be slow Or it can be fast with respect to the other devices May be the device which we have connected with the microprocessor it is slow in its operation or maybe it is fast in its operations so to Synchronize the working of the microprocessor with that device we have to apply a signal We have a signal ready signal so Microprocessor when it is connected to that device it sends a signal ready? So it means that that device is ready to be connected to the microprocessor or to synchronize with that? Microprocessor so whenever this signal is high It means that the different device which is connected to the microprocessor. It is ready for its operation So when the peripheral device it sends the ready signal then The microprocessor it gets an idea then the peripheral device. It is ready for its connection Then we have reset in pin number 36 Reset in This is an active low signal so when the signal is low it The microprocessor gets an idea that it has to reset the program counter, and it has to bring it to its initial conditions so it is used to reset the Program counter Then pin number 37 we have already Discussed it is the clock out signal then we have pin number 38 and 39 It is the hold of knowledge and volt signals pin number 38 and 39 Hold and hld These two signals are used to when the microprocessor 8:08 five it is connected to D mmm That it memory SS. When this is connected to DMA chip Then these two signals are used this we are going to study in detail When we will study the DMA operation and h08 five Then we have pin number forty Here it is the source the +5 volts power supply It is connected it is the VCC point So these are the 40 pins of the eight zero eight five represented in by the different signals again We have pin number one into the crystal is connected. Then we set out sword and set for the serial input-output data communication then we have the interrupt signals We have the lower order address and the data bus VSS ground pin Then the higher order address bus s not in s1 the status signals read/write and input output M bar these are the read/write and the input/output memory operations early address latch enable ready signal for the peripherals which are slow in their operation Resetting to reset the program counter to bring the program counter to its initial conditions clock out is for the output clock pulse a Hold and hota are used for the DMA operation and VCC is the +5 volts power supply connection? so in this video we studied the pin diagram of a 0 8 5 4 describing all the pins of the IC so I hope this video is clear to you, thank you

4 thoughts to “Pin Diagram – 8085 Microprocessor – Microprocessor”

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  2. U are just saying the full forms of pins.. For example I/O and M pin is Deir. we are using it active low for memory u said.. Dat is which memory from where it is taking for Wat purpose.. Ur aren't saying all these..

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