Set Interrupt Mask (SIM) :
In 8085 Instruction set, SIM stands for “Set Interrupt Mask”. It is 1-Byte instruction and it is a multi-purpose instruction.
The main uses of SIM instruction are –
- Masking/unmasking of RST7.5, RST6.5, and RST5.5
- Reset to 0 RST7.5 flip-flop.
- Perform serial output of data.
Read Interrupt Mask (RIM) :
In 8085 Instruction set, RIM stands for “Read Interrupt Mask”. It is a 1-Byte multi-purpose instruction.
It is used for the following purposes –
- To check whether RST7.5, RST6.5, and RST5.5 are masked or not.
- To check whether interrupts are enabled or not.
- To check whether RST7.5, RST6.5, or RST5.5 interrupts are pending or not.
- To perform serial input of data.
Difference between SIM and RIM instructions in 8085 microprocessor:
|Sr. No.||Sim Instruction||Rim Instruction|
|1||SIM stands for Set Interrupt Mask.||RIM stands for Read Interrupt Mask.|
|2||It is responsible for masking/unmasking of RST 7.5, RST 6.5 and RST 5.5.||It checks whether RST 7.5, RST 6.5, RST 5.5 are masked or not.|
|3||It resets to 0 RST 7.5 flip flop.||It checks whether interrupts are enabled or not and to check whether RST 7.5, RST 6.5 or RST 5.5 interrupts are pending or not.|
|4||The content of the Accumulator decides the action to be taken. So before executing the SIM instruction, it is mandatory to initialize Accumulator with the required value.||The contents of the Accumulator after the execution of the RIM instruction provide this information.Thus, it is essential to look into the Accumulator contents after the RIM instruction is executed.|
|5||SIM instruction can be used for serial output of data.||RIM instruction can be used for serial input of data.|
|6||Its opcode(in Hex) is 30.||Its opcode(in Hex) is 20.|
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