Interrupt generated by executing an instruction is called software interrupt. It's also called 'trap'. Software interrupts are generally used to make system calls i.e. to request operating system to perform an I/O operation or to run a new program.
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Assembly IA32:
An interrupt is a mechanism for hardware of software to interrupt the processor to go do something else. Playing music is a much higher level abstraction, and it is not valid to ask what is the interrupt to play music, partly because it depends on the specific hardware implementation.
A trap handler, also called an interrupt handler or interrupt service routine (ISR) is a program that executes when predefined events occur in a computer. There are software and hardware interrupts. An interrupt causes the computer's processor to stop running its current task and immediately run the trap handler to service the interrupt.
The lowest priority interrupt in the 8085 microprocessor is INTR, unless you also consider the software interrupts, RST 0 through RST 7, which are even lower.
RST 5.5 is level triggered interrupt & maskable also. it can be masked by using SIM intrruction. Vector address of the RST 5.5 interrupt is 002Ch
An interrupt (for example, Intel-based opcode 0xCD) causes the CPU to pause its current execution, store the state of the registers on the stack, then process a defined subroutine. When this subroutine completes, the interrupt finishes, the registers are restored from the stack, and the previous execution state resumes. Interrupts come in two basic flavors: hardware and software. A hardware interrupt occurs when a connected piece of hardware raises an IRQ signal. This mechanism tells the CPU that the hardware has information that needs to be processed. This is more efficient than polling for devices that have relatively few inputs or that have a latency that the CPU shouldn't wait for. Keyboards and mice are often interrupt-driven; the CPU only needs to know when something interesting has happened (a key was pressed or the mouse was moved, for example). Hard drives are also interrupt-driven; this allows the hard drive to locate the requested data and then return that data some CPU cycles later without the CPU having to request the status of the operation repeatedly. In contrast, a software interrupt is usually triggered by software as a means of invoking operating system code in a reliable manner. For example, in MS-DOS, a developer would call INT 0x21 in order to invoke typical DOS commands, such as reading or writing a file, obtaining keyboard input, and other basic operations. Most older operating systems running on Intel-compatible processors use software interrupts to provide a way for the program to access system functions. Newer operating systems use new opcodes that circumvent the need for software interrupts, although most platforms still provide this mechanism for legacy software.
There are 2 types interrupts in 8085 such as: 1)hardware interrupt 2)software interrupt
(Q)What are Hardware and software interrupt? draw the block daigram of 8259 interrupt controller and explain in brief..
The difference is that a hardware interrupt is a signal relayed to a system's CPU directly because of some piece of hardware, such as a keyboard or mouse. A software interrupt is a signal sent to indicate that something within a piece of software requires attention.
software interrupts
The TRAP interrupt can not be masked by software, unless there is hardware in place to allow that, perhaps by anding an output bit with the TRAP request line.
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.
Hardware Interrupt: Each CPU has External Interrupt lines(about 7). Other external devices line keyboard, Mouse, Other controllers can send signals to CPU asynchronously. Software Interrupt:is an interrupt generated with in a processor by executing an instruction . Software interrupt are often used to implemented system calls because they implemented a subroutine call with a CPU ring level change.
software
Interrupt is nothing but according to the priority of ur instruction the processor will assign memory to it and will keep the bus line busy .
The 8086 interrupt priorities are concerned ,software interrupt have the highest priority,followed by NMI ,followed by INTR.The lowest priority signals are unmaskable interrupts.
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.
The first is the real interrupt, when the external hardware interrupts the processors' work;the second is the exception, like page fault or division by zero;the third is the supervisor call (SVC) which is sometimes called interrupt (or 'software interrupt') as well.