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When you use a stack type instruction, such as PUSH B, you are using the effective address contained in the SP (Stack Pointer) register. In this example, m(SP-1) is set to B, m(SP-2) is set to C, and SP is set to SP-2.
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Explain the different addressing method with an example each?
Each instruction of a computer specifies an operation on certain data. The are various ways of specifying address of the data to be operated on. These different ways of specifying data are called the addressing modes. The most common addressing modes are:Immediate addressing modeDirect addressing modeIndirect addressing modeRegister addressing modeRegister indirect addressing modeDisplacement addressing modeStack addressing modeTo specify the addressing mode of an instruction several methods are used. Most often used are :a) Different operands will use different addressing modes.b) One or more bits in the instruction format can be used as mode field. The value of the mode field determines which addressing mode is to be used.The effective address will be either main memory address of a register.Immediate Addressing:This is the simplest form of addressing. Here, the operand is given in the instruction itself. This mode is used to define a constant or set initial values of variables. The advantage of this mode is that no memory reference other than instruction fetch is required to obtain operand. The disadvantage is that the size of the number is limited to the size of the address field, which most instruction sets is small compared to word length.INSTRUCTIONOPERANDDirect Addressing:In direct addressing mode, effective address of the operand is given in the address field of the instruction. It requires one memory reference to read the operand from the given location and provides only a limited address space. Length of the address field is usually less than the word length.Ex : Move P, Ro, Add Q, Ro P and Q are the address of operand.Indirect Addressing:Indirect addressing mode, the address field of the instruction refers to the address of a word in memory, which in turn contains the full length address of the operand. The advantage of this mode is that for the word length of N, an address space of 2N can be addressed. He disadvantage is that instruction execution requires two memory reference to fetch the operand Multilevel or cascaded indirect addressing can also be used.Register Addressing:Register addressing mode is similar to direct addressing. The only difference is that the address field of the instruction refers to a register rather than a memory location 3 or 4 bits are used as address field to reference 8 to 16 generate purpose registers. The advantages of register addressing are Small address field is needed in the instruction.Register Indirect Addressing:This mode is similar to indirect addressing. The address field of the instruction refers to a register. The register contains the effective address of the operand. This mode uses one memory reference to obtain the operand. The address space is limited to the width of the registers available to store the effective address.Displacement Addressing:In displacement addressing mode there are 3 types of addressing mode. They are :1) Relative addressing2) Base register addressing3) Indexing addressing.This is a combination of direct addressing and register indirect addressing. The value contained in one address field. A is used directly and the other address refers to a register whose contents are added to A to produce the effective address.Stack Addressing:Stack is a linear array of locations referred to as last-in first out queue. The stack is a reserved block of location, appended or deleted only at the top of the stack. Stack pointer is a register which stores the address of top of stack location. This mode of addressing is also known as implicit addressing.Read more: http://wiki.answers.com/Explain_the_different_types_of_addressing_modes_in_8085_microprocessor.#ixzz1VB4Smbt3
Explain different types of addressing mode?
Addressing modes are an aspect of the instruction set architecture in most central processing unit (CPU) designs. The various addressing modes that are defined in a given instruction set architecture define how machine language instructions in that architecture identify the operand (or operands) of each instruction. An addressing mode specifies how to calculate the effective memory address of an operand by using information held in registers and/or constants contained within a machine instruction or elsewhere.Number of addressing modesDifferent computer architectures vary greatly as to the number of addressing modes they provide in hardware. There are some benefits to eliminating complex addressing modes and using only one or a few simpler addressing modes, even though it requires a few extra instructions, and perhaps an extra register.[1] It has proven[citation needed] much easier to design pipelined CPUs if the only addressing modes available are simple ones. Most RISC machines have only about five simple addressing modes, while CISC machines such as the DEC VAX supermini have over a dozen addressing modes, some of which are quite complicated. The IBMSystem/360 mainframe had only three addressing modes; a few more have been added for the System/390.When there are only a few addressing modes, the particular addressing mode required is usually encoded within the instruction code (e.g. IBM System/390, most RISC). But when there are lots of addressing modes, a specific field is often set aside in the instruction to specify the addressing mode. The DEC VAX allowed multiple memory operands for almost all instructions, and so reserved the first few bits of each operand specifier to indicate the addressing mode for that particular operand. Keeping the addressing mode specifier bits separate from the opcode operation bits produces an orthogonal instruction set.Even on a computer with many addressing modes, measurements of actual programs[citation needed] indicate that the simple addressing modes listed below account for some 90% or more of all addressing modes used. Since most such measurements are based on code generated from high-level languages by compilers, this reflects to some extent the limitations of the compilers being used
In which addressing mode the effective address of the operand is generated by adding a constant value to the content of a register?
its register indirect with displacement.
What will be the addressing mode of instruction POP D in microprocesser 8085?
Stack/explicit.
What is the addressing mode of the instruction PCHL in 8085 microprocessor?
It is register addressing mode, as it moves the content of HL to PC which is data and not address.
How do you xxplain the types of memories?
Each instruction of a computer specifies an operation on certain data. The are various ways of specifying address of the data to be operated on. These different ways of specifying data are called the addressing modes. The most common addressing modes are:Immediate addressing modeDirect addressing modeIndirect addressing modeRegister addressing modeRegister indirect addressing modeDisplacement addressing modeStack addressing modeTo specify the addressing mode of an instruction several methods are used. Most often used are :a) Different operands will use different addressing modes.b) One or more bits in the instruction format can be used as mode field. The value of the mode field determines which addressing mode is to be used.The effective address will be either main memory address of a register.Immediate Addressing:This is the simplest form of addressing. Here, the operand is given in the instruction itself. This mode is used to define a constant or set initial values of variables. The advantage of this mode is that no memory reference other than instruction fetch is required to obtain operand. The disadvantage is that the size of the number is limited to the size of the address field, which most instruction sets is small compared to word length.INSTRUCTIONOPERANDDirect Addressing:In direct addressing mode, effective address of the operand is given in the address field of the instruction. It requires one memory reference to read the operand from the given location and provides only a limited address space. Length of the address field is usually less than the word length.Ex : Move P, Ro, Add Q, Ro P and Q are the address of operand.Indirect Addressing:Indirect addressing mode, the address field of the instruction refers to the address of a word in memory, which in turn contains the full length address of the operand. The advantage of this mode is that for the word length of N, an address space of 2N can be addressed. He disadvantage is that instruction execution requires two memory reference to fetch the operand Multilevel or cascaded indirect addressing can also be used.Register Addressing:Register addressing mode is similar to direct addressing. The only difference is that the address field of the instruction refers to a register rather than a memory location 3 or 4 bits are used as address field to reference 8 to 16 generate purpose registers. The advantages of register addressing are Small address field is needed in the instruction.
What is a direct page register?
This 8 bit register contains the most-significant byte of the address to be used in the direct addressing mode. The contents of this register are concatenated with the byte following the direct addressing mode operation code to form the 16-bit effective address. The direct page register contents appear as bits A15 through A8 of the address.
What are the adressing modes of 8085 microprocessor?
Different Addressing modes are: 1. Direct Addressing Mode 2. Indirect Addressing Mode 3. Immediate Addressing Mode 4. Register Addressing Mode 5. Implicit Addressing Mode Immediate addressing Data is present in the instruction. Load the immediate data to the destination provided. Example: MVI R,data Register addressing Data is provided through the registers. Example: MOV Rd, Rs Direct addressing Used to accept data from outside devices to store in the accumulator or send the data stored in the accumulator to the outside device. Accept the data from the port 00H and store them into the accumulator or Send the data from the accumulator to the port 01H. Example: IN 00H or OUT 01H Indirect Addressing This means that the Effective Address is calculated by the processor. And the contents of the address (and the one following) is used to form a second address. The second address is where the data is stored. Note that this requires several memory accesses; two accesses to retrieve the 16-bit address and a further access (or accesses) to retrieve the data which is to be loaded into the register.
What are addressing mode in microprocessor?
Addressing modes of 8051 are 1.Immediate Addressing Mode 2.Register Addressing Mode 3.Register Indirect Addressing Mode 4.Direct Addressing Mode 5.Implied Addressing Mode and 6.Relative Addressing Mode
What is the need of addressing mode?
The various addressing modes that are defined in a given instruction set architecture define how machine language instructions in that architecture identify the operand (or operands) of each instruction. An addressing mode specifies how to calculate the effective memory address of an operand by using information held in registers and/or constants contained within a machine instruction or elsewhere.
Difference between effective address and physical address?
The effective address is the address generated by the program, after all transformations, such as index registers, offsets, addressing mode, etc. have been made. The physical address is the address generated by the hardware, after performing whatever lookups through the page table, etc. have been made. The effective address, or virtual address, is the concern of the program. The physical address, or real address, is the concern of the operating system.
What are the different types of addressing modes?
literal and absolute direct are the registers
