Five Hardware Interrupts in 8085

• TRAP

• RST 7.5

• RST 6.5

• RST 5.5

• İNTR

SID and SOD Pin 4 (Input) and Pin 5 (Output)

• SID (Serial Input Data):
  • It takes I bit input from serial port of 8085.
  • Stores the bit at the 8th position (MSB) of the Accumulator.
  • RIM (Read Interrupt Mask) instruction is used to transfer the bit.

Maskable Interrupts

• Maskable interrupts are those interrupts which can be enabled or disabled.

• Enabling and Disabling is done by software instructions.

List of Maskable Interrupts:

RST 7.5

RST 6.5

RST 5.5

INTR

Non-Maskable Interrupts

• The interrupts which are always in enabled mode are called non-maskable interrupts.
• These interrupts can never be disabled by any software instruction.
• TRAP is a non-maskable interrupt.

Vectored Interrupts

• The interrupts which have fixed memory location for transfer of control from normal execution.
• Each vectored interrupt points to the particular location in memory.

List of vectored interrupts:

RST 7.5

RST 6.5

RST 5.5

TRAP

• The addresses to which program control goes:

• Absolute address is calculated by multiplying the RST value with 0008 H.

Non-Vectored Interrupts

• The interrupts which don't have fixed memory location for transfer of control from normal execution.
• The address of the memory location is sent along with the interrupt.
• INTR is a non-vectored interrupt.