Microcontroller PIC16F84 recognizes there are 4 kinds of source of interrupt. In general every source of the interrupt is alliances 2 interrupt bit. Firstly to enable interrupt and other detects the happen of interrupt. Side that is there is 1 public bit named by bit GIE (Global of Interrupt Enable bit).
Bit GIE very useful when program writing, because this bit is entitled to don't permit the happening of all interrupts at specified period causing execution at program key parts is not annoyed. When GIE is reset (GIE="0"), all interrupts will not be permitted. But, if this bit specified its the value becomes 1 interrupt will be considered. At the time of an interrupt is processed, bit GIE is cleaned so that existence of supplement interrupt will not be served.
Microcontroller PIC16F84 has existence of 4 source of interruption, that is:
1. External Interrupt at pin RB0/INT.
2. TMR0 does interrupt because timer overflows.
3. Interrupt at RB4, RB5, RB6 is at port B.
4. When writing of data at EEPROM completed.
