The 8085 has a
16-bit
register known as the ‘Stack Pointer. ‘ This register’s function is to hold the memory address of the stack.
What is the size of stack pointer in 8086 microprocessor?
It is of
16 bits
and is divided into two 8-bit registers DH and DL to also perform 8-bit instructions. It is used in multiplication an input/output port addressing. SP – This is the stack pointer. It is of 16 bits.
What is the size of a stack pointer?
There is a stack pointer and a instruction pointer, the stack pointer having 8 explicit and 8 implicit bits (stack is always in the same
256-byte
region) and thus the stack pointer register having 8 bits, the instruction pointer having 16 bits. The 8086, has an 16 bit databus and a 20 bit addressbus.
Why stack pointer is 16-bit?
The program counter acts as a pointer to the next instruction to be executed and always contains the 16-bit address of
the memory location of next instruction
. It is a 16 bit register as 8085 has 16 address lines.
Why stack pointer is 8-bit?
Why does the stack pointer holds only 8 bit address in 8051 and whereas the program counter holds the 16 bit address? that is the way it was designed. It has only 128 bytes of RAM, so an 8-bit stack pointer
is enough
. Using external RAM is possible, but requires a special instruction (MOVX).
What is stack example?
There are many real-life examples of a stack. Consider an example of
plates stacked over one another in the canteen
. The plate which is at the top is the first one to be removed, i.e. the plate which has been placed at the bottommost position remains in the stack for the longest period of time.
What is a stack vs heap?
Stack is a linear data structure whereas Heap is a hierarchical data structure
. … Stack variables can’t be resized whereas Heap variables can be resized. Stack memory is allocated in a contiguous block whereas Heap memory is allocated in any random order.
Where is stack pointer stored?
Simpler processors store the stack pointer in
a regular hardware register
and use the arithmetic logic unit (ALU) to manipulate its value. Typically push and pop are translated into multiple micro-ops, to separately add/subtract the stack pointer, and perform the load/store in memory.
What does a stack pointer do?
A stack pointer is a
small register that stores the address of the last program request in a stack
. … When a new data item is entered or “pushed” onto the top of a stack, the stack pointer increments to the next physical memory address, and the new item is copied to that address.
What is main stack pointer?
Main Stack Pointer (MSP) is
the default stack pointer
. It is used in the Thread mode when the CONTROL bit[1] (SPSEL) is 0, and it is always used in Handler mode. … Stack operations like PUSH and POP instructions, and most instructions that use SP (R13) use the currently selected stack pointer.
Why stack pointer is required?
The Stack Pointer (SP) register is
used to indicate the location of the last item put onto the stack
. When you PUT something ONTO the stack (PUSH onto the stack), the SP is decremented before the item is placed on the stack.
What is the top pointer of stack?
stack pointer is a
small register that stores the address of the last program request in a stack
. … The most recently entered request always resides at the top of the stack, and the program always takes requests from the top. A stack (also called a pushdown stack) operates in a last-in/first-out sense.
What is the difference between stack and stack pointer?
The stack is a LIFO (last in, first out) data structure implemented in the RAM area and is used to store addresses and data when the microprocessor branches to a subroutine. … The Stack Pointer register
will hold the address of the top location of the stack
.
How many bits are there in stack pointer?
Stack Pointer in 8085
The stack pointer is a
16-bit
register having a memory address.
Why do you think the size of the stack pointer in the 8051 is only 8 bits?
The stack pointer in the 8051 is 8-bits wide, and it can take a value of 00 to FFH. … This means that
the RAM location 08 is the first location used for the stack
. The storing operation of a CPU register in the stack is known as a PUSH, and getting the contents from the stack back into a CPU register is called a POP.
What is PSW explain each bit of it?
The Program Status Word (PSW)
contains status bits that reflect the current CPU state
. The 8051 variants provide one special function register called PSW with this status information. The 251 provides two additional status flags, Z and N, that are available in a second special function register called PSW1.
