Are 8259 and 8259A same?

The 8259A is upward compatible with 8259. The main difference between the two is that the 8259A can be used with Intel 8086/8088 processor. It also includes additional features such as level triggered mode, buffered mode and automatic end of interrupt mode.

How many ICWs are available in 8259A and in what sequence they are issued for 8259A initialization?

The 8259 Programmable Interrupt Controller can be initialized with four ICWs; the first two are compulsory, and the other two are optional based on the modes being used. These words must be issued in a given sequence.

What is microprocessor EOI?

EOI – (End Of Interrupt) : When the microprocessor acknowledges an interrupt request by sending the first INTA signal, the 8259 sets the corresponding bit in the In Service Register (ISR). This starts the service of the interrupt. When this bit in the ISR is cleared, then it is known as the end of interrupt (EOI).

What is the maximum number of 8259 that can be interfaced to a microprocessor?

When more than one 8259s are connected to the microprocessor, it is called as a cascaded configuration. A cascaded configuration increases the number of interrupts handled by the system. As the maximum number of 8259s interfaced can be 9 (1 master and 8 slaves) the maximum number of interrupts handled can be 64.

How many interrupts can be handled maximum by cascading?

64 interrupt
We can increase interrupt handling capability upto 64 interrupt level by cascading further 8259 PIC. Clock cycle is not required.

What is the role of 8259A?

This block is used to communicate between 8259 and 8085/8086 by acting as buffer. It takes the control word from 8085/8086 and send it to the 8259.

How many address input pins are available in 8259A?

28-pin
Intel 8259 is designed as a 28-pin-programmable IC available as a package named DIP (Dual inline package). Its physical and functional pin diagrams are indicated below. It is the Power supply and ground pins. +5V power supply isused in this chip.

How many interrupts can be connected 8259?

8 interrupts
8259 combines the multi interrupt input sources into a single interrupt output. Interfacing of single PIC provides 8 interrupts inputs from IR0-IR7. For example, Interfacing of 8085 and 8259 increases the interrupt handling capability of 8085 microprocessor from 5 to 8 interrupt levels.

How many interrupts lines are in pic?

The 8259 is known as the Programmable Interrupt Controller (PIC) microprocessor. In 8085 and 8086 there are five hardware interrupts and two hardware interrupts respectively.

How many interrupts can 8259A handle?

Intel 8259 is designed for Intel 8085 and Intel 8086 microprocessor. It can be programmed either in level triggered or in edge triggered interrupt level. We can mask individual bits of interrupt request register. We can increase interrupt handling capability up to 64 interrupt level by cascading further 8259 PIC.

What is the maximum number of interrupts that can be handled by 8259A?

We can increase interrupt handling capability upto 64 interrupt level by cascading further 8259 PIC.

What is the use of 8259 in microprocessor?

If 8259 is enabled, and the other microprocessor Interrupt flag is high then this causes the value of the output INT pin high and in this way 8259 responds to the request made by other microprocessor. It stores all the interrupt level which are requesting for Interrupt services.

What is the 8259A interrupt controller?

The 8259 combines multiple interrupt input sources into a single interrupt output to the host microprocessor, extending the interrupt levels available in a system beyond the one or two levels found on the processor chip. The 8259A was the interrupt controller for the ISA bus in the original IBM PC and IBM PC AT .

What is an Intel 8259A IRQ chip?

Closeup of an Intel 8259A IRQ chip from a PC XT. The Intel 8259 is a Programmable Interrupt Controller (PIC) designed for the Intel 8085 and Intel 8086 microprocessors. The initial part was 8259, a later A suffix version was upward compatible and usable with the 8086 or 8088 processor.

What is the 8259A PIC used for?

The 8259 Programmable Interrupt Controller (PIC) is one of the most important chips making up the x86 architecture. Without it, the x86 architecture would not be an interrupt driven architecture. The function of the 8259A is to manage hardware interrupts and send them to the appropriate system interrupt.