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 is the program counter register 16 bits instead of 8?
8 bit address can only locate/address 256 memory locations. 16 bit address can locate up to 64kb.
And hence the need of 16 bit PC & SP instead of 8 bits.
Is program counter a 16-bit register?
Lecture-13 PROGRAM COUNTER: This is a 16
bit register accessible to the user
. It always contain the address of the next instruction to be executed in a program sequence. Thus the program counter keeps the track of the program execution up to which it is complete.
Which is a 16-bit register for 8085 microprocessor?
Stack Pointer
: The stack pointer in the 8085 microprocessor is a 16-bit register that stores the address of the top of stack memory.
Why program counter is 16-bit register in 8051?
The designers of the 8051 separated
instruction
memory and data memory. There are more memory sections, but the stack is located in the latter, so this should suffice. Instruction memory: It has a maximum size of 65536 bytes that can be accesses without further “tricks”. To address this range you need 16 bits.
Which register is 16-bit?
A 16-bit
Data Segment register or DS register
stores the starting address of the data segment. Stack Segment − It contains data and return addresses of procedures or subroutines. It is implemented as a ‘stack’ data structure. The Stack Segment register or SS register stores the starting address of the stack.
Why is stack pointer 16-bit?
In 8086, the main stack register is called stack pointer – SP. The stack segment register (SS) is usually used to
store information
about the memory segment that stores the call stack of currently executed program. … These first instruction shall push the value stored in AX (16-bit register) to the stack.
Is accumulator a special purpose register?
Special Purpose Registers. (a) Register A(Accumulator) – Register A is an
8-bit register used in 8085 to perform arithmetic, logical
, I/O & LOAD/STORE operations. Register A is quite often called as an Accumulator. … And the result of the arithmetic operation will be stored or accumulated in this register.
Why the size of data register is 16 bit in basic computer?
PC/IP (Program Counter / Instruction Pointer, 12 bits) holds memory address of current/next instruction to be executed. … DR (Data Register, 16 bits) is
used to contain a second operand for dyadic operations such as add, sub, and, or
. TR (Temporary Register, 16 bits) is an extra register for storing data or addresses.
How many types of addressing are there in memory?
In this challenge we will focus on
four different
memory address modes: Immediate Access. Direct Access. Indirect Access.
How many registers are there in 8085?
The 8085 has
six
general – purpose registers to store 8-bit data; these are identified as B, C, D, E, H and L as shown in the figure. They can be combined as register pairs – BC, DE, and HL – to perform some 16-bit operations.
How many registers are in 8086?
Besides the
eight 16
bit registers, the 8086 CPUs also have eight 8 bit registers. Intel calls these registers al, ah, bl, bh, cl, ch, dl, and dh. You’ve probably noticed a similarity between these names and the names of some 16 bit registers (ax, bx, cx, and dx, to be exact).
What is the store by register?
A register may hold an instruction,
a storage address, or any kind of data
(such as a bit sequence or individual characters). … The effective address of any entity in a computer includes the base, index, and relative addresses, all of which are stored in the index register. A shift register is another type.
What is the use of Pcon register?
The PCON or Power Control register, as the name suggests is used
to control the 8051 Microcontroller’s Power Modes
and is located at 87H of the SFR Memory Space. Using two bits in the PCON Register, the microcontroller can be set to Idle Mode and Power Down Mode. NOTE: PCON register is not bit addressable.
What is the purpose of PSW register?
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.
What is the function of DPTR register?
DPTR is meant for
pointing to data
. It is used by the 8051 to access external memory using the address indicated by DPTR. DPTR is the only 16-bit register available and is often used to store 2-byte values.
