What are the instructions performed by RET n instruction?
The call nn appears to behave just like a jp nn instruction but it also causes the address of the next instruction, the return address, to be automatically saved. The ret instruction behaves like a jump to the return address, that is, the location following the call.
What is RET instruction in microprocessor?
RET is the instruction used to mark the end of sub-routine. After execution of this instruction program control is transferred back to main program from where it had stopped. Value of PC (Program Counter) is retrieved from the memory stack and value of SP (Stack Pointer) is incremented by 2.
When RET instruction is executed by any subroutine then?
When RET instruction is executed by any subroutine then two bytes from the top of the stack will be popped out and assigned to the Program counter and the program execution begins at the new address.
What is RET equivalent to in assembly?
ret is basically how you write pop eip (or IP / RIP) in x86, so popping into an architectural register and using a register-indirect jump is architecturally equivalent.
How does Ret work in assembly?
Description. The ret instruction transfers control to the return address located on the stack. This address is usually placed on the stack by a call instruction. Issue the ret instruction within the called procedure to resume execution flow at the instruction following the call .
What does mean by Ret 4?
ret 4 just returns like usual but then adds 4 to the stack pointer ( esp ) so you don’t have to pop word2 pop word1 off the stack after returning from the call, therefore it cleans/balances the stack without needing to pop the previous pushes.
What does Ret mean in coding?
return value
What is RETI instruction?
The RETI instruction is used to end an interrupt service routine. This instruction pops the high-order and low-order bytes of the PC (and decrements the stack pointer by 2) and restores the interrput logic to accept additional interrupts. No other registers are affected by this instruction.
What is the difference between the RET and IRET instructions?
The IRET instruction is used to exit from an interrupt procedure. IRET is similar to RET except that IRET increments ESP by an extra four bytes (because of the flags on the stack) and moves the saved flags into the EFLAGS register. The IOPL field of EFLAGS is changed only if the CPL is zero.
What does the NOP instruction do?
A NOP is most commonly used for timing purposes, to force memory alignment, to prevent hazards, to occupy a branch delay slot, to render void an existing instruction such as a jump, or as a place-holder to be replaced by active instructions later on in program development (or to replace removed instructions when …
What is DJNZ in 8051?
The DJNZ instruction decrements the byte indicated by the first operand and, if the resulting value is not zero, branches to the address specified in the second operand.
What is Subb in 8051?
The SUBB instruction subtracts the specified byte variable and the carry flag from the accumulator. The result is stored in the accumulator. This instruction sets the carry flag if a borrow is required for bit 7 of the result. If no borrow is required, the carry flag is cleared.
How can you put the 8051 in idle mode?
Idle Mode: 8051 can be put in idle mode by making bit 0 of PCON as 1. Input clock to CPU is stopped and CPU stops working.
What is the function of Pcon register?
PCON (Power Control) register is used to force the 8051 microcontrollers into power-saving mode. The power control register of 8051 contains two power-saving mode bits and one serial baud rate control bit.
Which state indicates that the CPU is in power down mode?
Symptoms
| Mode | Name | What it does |
|---|---|---|
| C3 | AltVID | Stops all CPU internal clocks and reduces CPU voltage |
| C4 | Deeper Sleep | Reduces CPU voltage |
| C4E/C5 | Enhanced Deeper Sleep | Reduces CPU voltage even more and turns off the memory cache |
| C6 | Deep Power Down | Reduces the CPU internal voltage to any value, including 0 Volts |
What is the use of P Con register?
PCON (Power control) register is used to force the 8051 microcontroller into power saving mode. Power control register of 8051 contains two power saving mode bits and one serial baud rate control bit.
What is function of SCON register?
Using SCON, you can control the Operation Modes of the Serial Port, Baud Rate of the Serial Port and Send or Receive Data using Serial Port. SCON Register also consists of bits that are automatically SET when a byte of data is transmitted or received.
Which register is a power control register?
Explanation: The power control register is used for power saving during idle state of the microcontroller and eventual power off to the microcontroller chip. It has SMOD bit which is used to double the baud rate. Explanation: ALE and PSEN(active low) remain high in Idle mode.