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DI = Disable all interrupts (except TRAP)
EI = Enable all interrupts
Also, SIM can selectively mask RST5.5, RST6.5, and RST7.5.
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What is an 8085 interrupt?
There are 2 types interrupts in 8085 such as: 1)hardware interrupt 2)software interrupt
What does unmask mean?
were you take your mask off and show who you really are
What actors and actresses appeared in Unmask in the Dark - 2012?
The cast of Unmask in the Dark - 2012 includes: Ella Eranthis as Girl in mask
Which register is used to set priority for interrupts?
The 8085 does not have an adjustable priority interrupt schema. You can only turn interrupts off, and mask certain interrupts, such as RST5.5, RST6.5, and RST7.5. However, that said, you can implement a priority schema, of sorts, within these interrupts, including INTR, by using the SIM instruction. You can't change the basic priority but you can disable certain interrupts while others are being serviced, if you so choose.
What is the meaning of maskable hardware interrupt?
A maskable hardware interrupt is one that can be disabled, or masked, by instructions in the CPU. In the 8085, all interupts except TRAP and (software) RST N can be masked by disabling interrupts, and RST7.5, RST6.5, and RST5.5 can be individually masked with the SIM (Set Interrupt Mask) instruction. In general, you leave interrupts disabled until one instruction before returning. In the case of the RST*.5 interrupts, you can mask it during interrupt processing and then enable interrupts, allowing other levels to interrupt you again. At the conclusion of the interrupt routine, you would disable interrupts, restore the mask, enable interrupts, and return. If you use this method, you can choose the nesting priority as desired. You determine what mask to set using the RIM (Read Interrupt Mask) instruction and then do bit manipulation before using SIM.
What are the pins used to control interrupts?
The pins used to control interrupts in the 8085 are INTR/INTA, RST5.5, RST6.5, RST7.5, and TRAP.
Why do you need 8085 maskable interrupts if they can be disabled?
if u want to execute high priority interrupt,at that time of low priority running.So, we can mask the low priority interrupt and execute the high priority interrupt.
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.
Should any device be allowed to interrupt CPU while another interrupts are being serviced?
It is possible to allow nested interrupts. This is often done when there is a heirarchy of interrupts, some with higher priority than others. In order for this to work, the second interrupt must not be allowed to influence the progress of the first interrupt. We call this being "thread safe". In a nested scheme, an interrupt mask is set so that higher priority interrupts can be permitted, while blocking interrupts of the same or lower priority, and then interrupts are reenabled during the interrupt service routine. At the conclusion of the first routine, interrupts are disabled again, the mask is restored, and the normal interrupt return sequence is executed. In the 8085, this can be supported using the Read Interrupt Mask (RIM) and Set Interrupt Mask (SIM) instructions. While not strictly required, the logical priority is often INTR, RST5.5, RST6.6, RST7.5, and then TRAP, in order of increasing priority.
Difference between 8080 and 8085?
The 8085 has a single +5V power supplyThe 8085 has a multiplexed low order address busThe 8085 has extra single pin interrupts, TRAP, RST7.5, RST6.5, and RST5.5The 8085 has serial I/O pins SID and SODThe 8085 has maskable interrupts and the RIM/SIM instructionThe 8085 includes the functionality of the 8224 clock genereator and 8228 system controllerThe 8085 added several 16 bit operations
What are the applications of hardware interrupts in 8085?
The hardware initiates an interrupt when it feels that the situation requires the CPU's action.
What happens when processor is attending an interrupt if it gets another interrupt?
The response to another interrupt request during servicing of an interrupt depends on the setting of the interrupt enable flag and/or the interrupt mask. If the interrupt service routine is thread safe, it will process correctly. More probably, problems will arise so the proper procedure is to either set the interrupt mask (8085) to not allow this or lower priority interrupts before reenabling interrupt, or to leave interrupts disabled until this iteration is complete. If interrupts are disabled or masked, a subsequent interrupt will be posted but not processed until the first is completed.
