0
Want this question answered?
Be notified when an answer is posted
Add your answer:
Earn +20 pts
What is rim in microprocessor 8085?
RIM is Read Interrupt Mask. It is used to access the interrupt mask register, which contains the status of the three interrupt masks and the serial input data pin.
A CPU generally handles an interrupt by executing an interrupt service routine?
By checking the interrupt register at fixed time intervals
When an IRET instruction is executed what action takes place?
By ABDULLAH ABID Secretary Info & IT GLOBAL PEACE COUNCIL PAKISTAN. http://h.1asphost.com/gpcp/org The Interrupt-In-Service-Flag is set at the beginning of an interrupt-acknowledge cycle. It is reset by the IRET (Interrupt-RETurn) instruction. When IIS is set, interrupts are disabled. When the Status-register is read, IIS always reads as '0'.
What is interrupt mechanism?
At the beginning of each FDE cycle, each bit in the interrupt register is checked in turn. This register is a special register in the CPU that takes note of when an interrupt has happened. Each bit in the register represents a different kind of interrupt. If a bit has been set, that would indicate an interrupt has happened! The CPU has to decide whether to service the interrupt immediately, or leave it till later. For example, if 2 interrupts have happened at the same time, one of them has to wait! Which one? That depends upon which one is the least important! Some interrupts are more important than others and so need to be done before others. What about the situation where one interrupt is currently being serviced by the CPU and another happens? Again, it depends on how important the new interrupt is compared to the one already being done. If it is more important, then the cpu will want to service it immediately. When the CPU decides to service an interrupt, it stops processing the current job, 'pushing' the contents of its registers onto the stack. This would include, for example, the contents of the Program Counter and the accumulator. The CPU is now free to work on another piece of software but can return to what it was doing after the interrupt has been serviced because it has saved where it was. It then transfers control to the interrupt handling software for that type of interrupt using the vectored interrupt mechanism. When it has finished servicing the interrupt, the contents of the stack are 'popped' back into the appropriate registers and the CPU continues from where it left off before the interrupt happened.
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 is the difference between context switching and interrupt handler?
they're not totally indistinguishable, they overlap as one is needed for the other. context switching is the process of storing and restoring the state of a process. when a interrupt handler interrupts a program, the context switch is enacted. the current programs status is saved and then once the program interrupt is finished, then program interupted is restored. the program interrupting is the computers way of responding to outside stimuli. in simple terms it saves the programs status, deals with what ever the interrupt is, then restores the programs status (what ever said program happens to be).
Can you still register a vehicle when it is in repossession status?
not possible. sorry
What are the two hex address locations of the Status Register?
o3h,04h
What are the different steps to invoke ROM bios function?
the following steps are required to invoke a rom-bios function 1)make an interrupt to occur 2)find out the number of the interrupt that has occurred. 3)obtain from IVT,the address of the ISR which services this interrupt. 4)push the current values of CPU register onto the STACK
What is difference between vectored and non vectored interrupts?
Vector interrupt --> when processor directly call the respective isr when interrupt occurs so, address of respective isr is usually save in register. Non interrupt Vector --> In this case when interrupt occurs the processor calls a generic isr and in generic isr uaer has to call respective isr by checking status register.
What is psw of 8086?
Flag Register (PSW)Status is indicated with individual bits: 0 - CF - Carry Flag2 - PF - Parity Flag4 - AF - Auxiliary carry Flag6 - ZF - Zero Flag7 - SF - Sign Flag8 - TF - Trap Flag9 - IF - Interrupt Flag10 - DF - Direcetion Flag11 - OF - Overflow Flag
Why there is a need for disabling interrupts in 8085?
Interrupt are automatically disabled on interrupt entry (except for TRAP, which is non-maskable) so that interrupts do not, by default, nest. You would also disable enterrupts surrounding a critical section of code that, perhaps, manipulated an interrupt register. It is possible to re-enable interrupts during an interrupt service routine. Typically, you would have a hierarchy, such as RST7.5, then RST 6.5, then RST 5.5. Initially, at interrupt entry, all interrupts are disabled. You could then manipulate the interrupt mask using the RIM and SIM instructions and enable further interrupts, allowing a nested architecture. At interrupt exit, then, you would disable interrupts, reset the mask, enable interrupts, and return from interrupt.
