 I am Mr. S.S. Shakhapure, Assistant Professor, Department of Computer Science and Engineering, Vulture and the Institute of Technology, Solapur. My today's discussion topic is types of 8086 interrupts. My learning outcome at the end of this session to understand and analyze the types of interrupts and access of interrupts when interfacing IO devices. What is interrupt? The interrupt is to break the sequence of operations. Or we can say it is a temporary hold during the execution of a particular process and again written back to the main operation. And an interrupt is used to cause a temporary hold. An interrupt is either a hardware-generated call or we can say a software-generated call. A hardware-generated call is nothing but it generates externally from peripheral devices and a software-generated interrupt is a program instruction which is added or insert in the execution of any particular program. So if you are looking, the types of interrupts can be divided into two different parts. One is hardware interrupt and another one is software interrupt. About the hardware interrupt, if you are looking, the hardware interrupts, we can count in a maskable type and one is in a non-maskable type. In the maskable type of the programmers can choose to mask specific interrupts and re-enable them later. That means here in the maskable interrupts, we can able to control the interrupts which we are going to generate in the execution of the program and about the non-maskable interrupts where the programmers cannot control when a non-maskable interrupt is served. So this indicates here we could not able to manage or control on the interrupts if once it gets generated and the processor has to stop the main program to execute such a non-maskable interrupt. Now about the software interrupts, there are software interrupts like INTN and these are total 256 different types of software interrupts is available about the hardware interrupt. Hardware interrupt is caused by any peripheral devices by sending a signal through specified pin to the microprocessor. Now what exactly the specified pin? The 8086 has two hardware interrupt pins that is NMI and INTR. NMI is non-maskable interrupt and INTR is a maskable interrupt having lower priority. One more interrupt pin associated is INTA called interrupt acknowledgement. So if you are observing here, now in the hardware interrupt we are majorly focusing on NMI and INTR. If you are observing 8086 IC about the maskable interrupt you can able to see pin number 18 as INTR and about the pin number 17 here you can able to see the non-maskable pin NMI hardware interrupts. In the 8086 interrupt pins INTR that is interrupt request is activated by peripheral device to interrupt the processor and this INTR is a level triggered activated with a logic 1 and about the INTA it is interrupt acknowledgement is activated by the processor to inform the interrupting device to the interrupt request when it is accepted and it is a level triggered activated with a logic 0. Now in the second of the hardware interrupt pin NMI it is a non-maskable interrupt is used for major system faults such as parity errors and power failures that means once it generated it will not be able to control by the programmers so it is as triggered activated with the positive edge transition must remain at logic 1 until it is accepted by the processor and before the 0 to 1 transition NMI must be at logic 0 for a list 2 clock cycles and this one is no need for interrupt acknowledgement so about the think and write I have a question and this question is based on our previous discussion please check it out the INTR interrupt may be I have the 4 options please think a question on this the options are maskable, non-maskable, maskable and non-maskable and then of the mention so your answer is A the INTR that is interrupt request is maskable or we can say it can be disabled now we are moving the second part of the types of interrupt that is software interrupts software interrupts here some instructions are inserted at the desired position into the program to create interrupts and these interrupt instructions can be used to test the working of various interrupt handlers and it includes INT interrupt instruction interrupt instruction consisting with different type of numbers what exactly these different type of numbers we will check it out so software interrupts it is a 2 byte instruction and first byte it provides the opcode and the second byte provides the different type of type number which we mentioned so here the total 256 different kinds of interrupt type number under this group its execution includes the following steps flag register value is pushed onto this tag cs value of the written address and the ip value of the written address are pushed onto this tag and the ip is loaded from the content of the word location that is type number into 4 and the cs is loaded from the contents of the next word location interrupt flag and trap flag are reset to 0 so these are what different steps which we are including while executing the software interrupt in the program now about the software interrupts all 8086 processors provide the following instruction related to interrupts so my interrupt instruction is like INTNN that is interrupt a particular type number and these runs the ISR pointed by vector number so I have some important instruction that is one example like INT0 is reserved for the divide error like this INT1 is reserved for single step operation next like INT2 is reserved for the NMI pin INT3 is reserved for setting a breakpoint INT4 is reserved for overflow and the interrupts from type INT5 to 255 they are like reserved for the advanced kind of microprocessors now about the summary section a general purpose computer depends on its ability to interact with IO device attached to it and the devices requires a prompt response from the CPU when various event occurs even when the CPU is busy running a program so for these about different kind of requirement we need a mechanism for a device to gain CPU attention and this can possible with the help of requesting different kind of interrupts generating in the program so interrupts provides a way doing this that is an interrupt is a special condition that arises during the working of a microprocessor and the microprocessor services it by executing a subroutine called ISR and through this or through circuit we can check behavior and consideration of devices and these are what my references which I use thank you