Those would be software interrupts. Interrupts initiated by the hardware would be hardware interrupts. While the socket a mouse is plugged into would use a hardware interrupt, a mouse driver would use a software interrupt.
interrupt is a disturbance ,and request to do various jobs unusually while executed to be in current process in a system
interrupts in 8085 are basically classified into two types: 1.Maskable 2.Non maskable maskable interrupts are those which can be delayed.This is done by masking off the interrupts which are not required. Maskable interrupts are:RST 7.5,RST 6.5,RST 5.5 and INTR <decreasing order of priority>
interrupt handling is the process of handling a break or interrupt called by a program where as exception handling is for handling some exceptional conditions that'll occur when a program is running
Memory mapped IO uses a portion of RAM to handle IO requests. In this manner, instructions the CPU uses for reading and writing memory can also be used for IO, reducing the circuitry needed. This makes the CPU simpler, cheaper and more effecient.
1.Programmed IO is the process of IO instruction written in computer program , where Interrupt Initiated IO is done by using interrupt and some special command. 2.The advantage of Interrupt Initiated IO is ,it is a time consuming process than Programmed IO. 3.In Programmed IO technique to transfer data,required constant motoring on peripheral by CPU,once data transfer is initiated, CPU have to wait for next transfer. In Interrupt Initiated IO once data transfer initiated ,CPU execute next program without wasting time and the interface keep monitoring the device. When the interface determines that the device is ready to transfer data, it generate an interrupt request,CPU stop the current task,execute the transferring process,and then return to the previous on-processing task.
disadvantages of interrupt
software
Interrupt signals initiated by programs are called software interrupts. A software interrupt is also called a trap or anexception. A signal informing a program that an event has occurred. When a program receives an interrupt signal, it takes a specified action (which can be to ignore the signal). Interrupt signals can cause a program to suspend itself temporarily to service the interrupt. Interrupt signals can come from a variety of sources. For example, every keystroke generates an interrupt signal. Interrupts can also be generated by other devices, such as a printer , to indicate that some event has occurred. PCs support 256 types of software interrupts and 15 hardware interrupts. Each type of software interrupt is associated with an interrupt handler -- a routine that takes control when the interrupt occurs. For example, when you press a key on your keyboard, this triggers a specific interrupt handler. The complete list of interrupts and associated interrupt handlers is stored in a table called the interrupt vector table , which resides in the first 1 K of addressable memory.
Those would be software interrupts. Interrupts initiated by the hardware would be hardware interrupts. While the socket a mouse is plugged into would use a hardware interrupt, a mouse driver would use a software interrupt.
It does not require the continuous checking of I/O port by the computer . The computer checks the port only when an I/O interrupt is encountered . It saves processing time.
A hardware interrupt is initiated from a hardware event, such as a byte received from a serial port. It is asynchronous to the running program, i.e. it can occur at any time. An internal, or software, interrupt is initiated by the running program, thus it is under the control of the running program. In the 8085, for instance, the RST instructions are software interrupts. Note, however, that external interrupts can initiate a software RST instruction, so the two events can appear to be the same kind of event. The biggest difference is the handling of the interrupt enable (IE) flag. In the hardware interrupt, the IE flag is turned off when processing the interrupt, and it is turned on right before the interrupt service routine executes the final return instruction. The software interrupt, on the other hand, has nothing to do with IE. As a result, the code must be able to tell the difference.
An interrupt is generally initiated by an I/O device, and causes the CPU to stop what it's doing, save its context, jump to the appropriate interrupt service routine, complete it, restore the context, and continue execution. For example, a serial device may assert the interrupt line and then place an interrupt vector number on the data bus. The CPU uses this to get the serial device interrupt service routine, which it then executes as above.A trap is usually initiated by the CPU hardware. When ever the trap condition occurs (on arithmetic overflow, for example), the CPU stops what it's doing, saves the context, jumps to the appropriate trap routine, completes it, restores the context, and continues execution. For example, if overflow traps are enabled, adding two very large integers would cause the overflow bit to be set AND the overflow trap service routine to be initiated.
Blocking IO: The program will pause and wait until the IO operation is complete before resuming. This technique can lead to inefficiency if there are multiple IO operations. Non-blocking IO: The program continues to run while waiting for the IO operation to complete. This allows for better efficiency when handling multiple IO operations simultaneously. Asynchronous IO: The program initiates the IO operation and continues executing, without waiting for the operation to complete. A callback function is usually provided to handle the result once it is available. This allows for better performance in handling large numbers of IO operations.
Maybe you have seen something called an interrupt as you work on your computer. These Interrupt Requests come from processes or devices that want to use resources. It's all very orderly.
An interrupt is a request to execute different code, initiated usually by a hardware condition such as data-ready or operation-complete, but also sometimes initiated by the running program. The processor saves its immediate state, IP and Flags, on the stack and loads a new IP value, effectively doing a CALL sequence to some interrupt service routine. The routine does whatever processing is required, and returns, restoring the running program. Under normal conditions, the interrupt response sequence disables further interrupts, so that recursive entry does not occur. The service routine reenables interrupts just before returning, so that pending or further interrupts can be processed. If multiple interrupt levels are to be supported, such as in the 8085, the interrupt service routine can set the interrupt mask, blocking the level in progress, and then reenable interrupts. This way, a second interrupt on a higher level can be processed while the first interrupt is being processed. On return, the lower level interrupt disables interrupts, restores the mask, and then reenables interrupts prior to return.
Polling checks constantly the status of de I/O device, wasting CPU cycles. However with Interrupt driven I/O the device sends a request to the CPU to indicate that it needs attention. So, in some cases, Interrupt driven I/O will be better than polling, because doesn't waste CPU cycles checking when the device needs attention.