![]() Masking or unmasking has to be done using the SIM instruction. Note that they are not used for masking or unmasking. Mask status of interrupts: The LS 3 bits of the accumulator are used to provide mask status of interrupts. The meaning of the various bits of the Accumulator after RIM is executed is shown in the following figure – Thus, it is essential to look into the Accumulator contents after the RIM instruction is executed. The contents of the Accumulator after the execution of the RIM instruction provide this information. Through this RIM instruction, 8085 can know which interrupt is masked or unmasked, etc. To get the status information about the interrupt system, RIM instruction provides status information about interrupt system and this instruction can be used for serial input of data. To check whether RST7.5, RST6.5, or RST5.5 interrupts are pending or not To check whether interrupts are enabled or not To check whether RST7.5, RST6.5, and RST5.5 are masked or not It is a 1-Byte multi-purpose instruction. In 8085 Instruction set, RIM stands for “Read Interrupt Mask”. Masking of interrupts: Only the LS 4 bits of the accumulator are used for masking or unmasking of interrupts. Note that except bit 5, which is a don't care bit, the other bits of the Accumulator decide the effect of executing the SIM instruction. The meaning and purpose of the various bits of the accumulator when SIM is executed has been depicted below – So before executing the SIM instruction, it is mandatory to initialize Accumulator with the required value. Naturally, these operating systems have registries. ![]() The most familiar of these are Windows XP64, Windows Vista64 and Windows 7 X64. For a 64 bit computer to function it needs to be running a 64 bit operating system. When SIM instruction is executed then the content of the Accumulator decides the action to be taken. Another of the 64 bit troubles many of us are encountering is keeping the registry free of corruption. Masking/unmasking of RST7.5, RST6.5, and RST5.5 When SEL1 input B is connected to the output Z. When SEL0 input A is connected to the output Z. It is 1-Byte instruction and it is a multi-purpose instruction. This 2:1 MUX has two data inputs (A,B), one output (Z) and an input (SEL), selecting which one of the two data inputs should be connected to its output, as defined by its truth table shown in the bottom of figure 3. In 8085 Instruction set, SIM stands for “Set Interrupt Mask”. In 8085 Instruction set, SIM (Set Interrupt Mask) and RIM (Read Interrupt Mask) instructions can perform mask and unmask RST7.5, RST6.5, and RST5.5 interrupt pins and can also read their status.
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