Table of Contents
- 1 What happens when push instruction is executed?
- 2 What does pushing a register do?
- 3 What registers are set during the execution of an instruction?
- 4 What is the result for push PSW?
- 5 What are the functions of push and pop instructions?
- 6 Which type of instruction push is?
- 7 Which flag is affected after execution of test instruction?
- 8 How many flags are affected after executing CMP instruction?
- 9 What is a PUSH instruction in x86?
- 10 Which instruction pushes the data in the stack?
What happens when push instruction is executed?
In PUSH instruction, after each execution of the instruction, the stack pointer is a) incremented by 1 b) decremented by 1 c) incremented by 2 d) decremented by 2 Answer: d Explanation: The actual current stack-top is always occupied by the previously pushed data.
What does pushing a register do?
The easiest and most common way to use the stack is with the dedicated “push” and “pop” instructions. “push” stores a constant or 64-bit register out onto the stack. The 64-bit registers are the ones like “rax” or “r8”, not the 32-bit registers like “eax” or “r8d”. “pop” retrieves the last value pushed from the stack.
What registers are set during the execution of an instruction?
Data flow (Fetch Cycle) The PC contains the address of the next instruction to be fetched. This address is moved to the MAR and placed on the address bus. The control unit requests a memory read, and the result is placed on the data bus and copied into the MBR and then moved to the IR.
Which register stores the status after execution of each instruction?
The status register is a hardware register that contains information about the state of the processor. Individual bits are implicitly or explicitly read and/or written by the machine code instructions executing on the processor.
Which flag is affected after execution of push or pop instruction?
No flags are affected.
What is the result for push PSW?
Let us consider PUSH B as an example instruction of this category. It is a 1-Byte instruction. The result of execution of this instruction is shown below with an example….Instruction type PUSH rp in 8085 Microprocessor.
| Mnemonics, Operand | Opcode(in HEX) | Bytes |
|---|---|---|
| PUSH PSW | F5 | 1 |
What are the functions of push and pop instructions?
Instructions that store and retrieve an item on a stack. Push enters an item on the stack, and pop retrieves an item, moving the rest of the items in the stack up one level.
Which type of instruction push is?
In 8085 Instruction set, PUSH rp instruction stores contents of register pair rp by pushing it into two locations above the top of the stack….Instruction type PUSH rp in 8085 Microprocessor.
| Mnemonics, Operand | Opcode(in HEX) | Bytes |
|---|---|---|
| PUSH D | D5 | 1 |
| PUSH H | E5 | 1 |
| PUSH PSW | F5 | 1 |
Which type of registers is used in program execution?
These are various registers required for execution of instruction : Program Counter (PC), Instruction Register (IR), Memory Buffer (or Data) Register (MBR or MDR), and Memory Address Register (MAR).
What is a temporary register?
A temporary register is the only register that can be read and written more than once in a single instruction. Each temporary register has single-write and triple-read access. Therefore, an instruction can have as many as three temporary registers in its set of input source operands.
Which flag is affected after execution of test instruction?
CMP and TEST instructions affect flags only and do not store a result (these instruction are used to make decisions during program execution). These instructions affect these flags only: CF, ZF, SF, OF, PF, AF.
How many flags are affected after executing CMP instruction?
only carry and zero flags will be affected. no flags will be affected. While CMP B instruction executes, microprocessor compares the contents of register B with the contents of the accumulator.
What is a PUSH instruction in x86?
A push is a single instruction in x86, which does two things internally. Decrement the ESP register by the size of pushed value. Store the pushed value at current address of ESP register.
Is push and pop a register or not?
The explicit operand for push and pop is r/m, not just register, so you can push dword [esi]. Or even pop dword [esp]to load and then store the same value back to the same address. (github.com/HJLebbink/asm-dude/wiki/POP). I only mention this because you say “not necessarily a register”.
What happens when a CPU fetches an instruction?
The fetched instruction (stored in the instruction register ) is the executed (the CPU will do the operation indicated by the instruction code in the instruction register ) The CPU will cause the memory to retrieve (recall) the value stored at memory address (location) 1
Which instruction pushes the data in the stack?
The PUSH instruction pushes the data in the stack. The format of PUSH instruction is: It decrements the stack pointer by two and then stores the data from the source operand at the position of the stack pointer. The source operand can be a general-purpose register, segment register or a memory address but it should be a word.