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Why might you have a resource sharing problem if you install a serial port on both COM2 and COM4?
COM2 and COM4 use the same interrupt by default (IRQ3). The same is also true for COM1 and COM3 (IRQ4).
What is irq3 used for?
IRQ Interrupt Request 3 are usually reserved for COM port (1,2,3,4) but can be assigned to anything.Interrupts are a commonly used technique for computer multitasking, especially in real-time computing. Such a system is said to be interrupt-driven.An act of interrupting is referred to as an interrupt request (IRQ
What IRQ does COM2 use?
COM2 typically uses IRQ 3. The Interrupt Request (IRQ) is a signal used by hardware devices to get the attention of the CPU. In the case of COM2, which is a communication port, it uses IRQ 3 to communicate with the CPU for data transmission and reception.
Which is a correct default combination of COM ports and IRQ?
Hi, correct combination of default combination of COM ports and IRQ is given below: 1. com1 and com3 - IRQ4 2. com2 and com4 - IRQ3 below link can easily explain the answer in details. You can even see this in device manager properties. i.e. mycomputer > properties > device manager> IDE/ATA controller > resources > irq=20 link : http://www.webopedia.com/quick_ref/IRQnumbers.asp
Why you should disable interrupts while hooking interrupt 8H?
Question_1: The following code reads port 0x21 (interrupt mask register) of PIC (Programmable Interrupt Controller), sets the 2nd bit that is mapped to IRQ1 and writes it back to port 0x21. As a result keyboard interrupt will be disabled as IRQ1 is used by keyboard. [10 marks] ; disable keyboard interrupt in PIC mask register 01 [org 0x0100] 02 in al, 0x21 ; read interrupt mask register 03 or al, 2 ; set bit for IRQ1 04 out 0x21, al ; write back mask register 05 mov ax, 0x4c00 ; terminate program 06 int 0x21 Modify instruction_03 for the following: I. set bit for IRQ0 II. set bit for IRQ6 III. set bits for IRQ1, IRQ3 and IRQ4 IV. clear bit for IRQ5 V. clear bits for IRQ2, IRQ5, IRQ6 and IRQ7Question_2: Suggest a reason for the following: [5 marks] I. We should disable interrupts while hooking interrupt 8h, i.e. while placing its segment and offset in the interrupt vector table. II. We need not do this for interrupt 80h.
What are the 12 interrupts in 8085?
An interrupt in the 8085, like in most computers, is a request to execute code out of sequence, usually by an external event, such as a signal from an IO device. In the 8085, an interrupt is almost exactly like a CALL instruction, except that the accumulator and flags register is also pushed on the stack. (Recall that the CALL instruction only pushes the return address on the stack.)This means that to return from an interrupt you must also pop the accumulator and flags, and this is done simply with the IRET instruction, as opposed to the RET instruction. In the 8085, the interrupt addresses are located in low memory, though the actual interrupt address could be anywhere if the interrupting device is capable of generating the three byte CALL sequence instead of the simpler INTx sequence, or the even simpler INTx.5 sequence.
