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What must the address field of an indexed addressing mode instruction be to make it the same as a register indirect mode instruction?
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-Aval Preet Singh
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What must the address be of an indexed addressing mode instruction be to make it same as a register indirect mode instruction?
zero -Aval Preet Singh
What is the difference between register addressing mode and register indirect addressing mode?
Ans: In the register addressing mode the operands are in registers which reside within the CPU. Register-mode instructions are 1-byte instructions and can be executed within the CPU without the need to reference memory for operands. But in the Register-indirect addressing mode the instruction specifies a register or a pair of registers in the processor whose contains give the address of the operand in memory. This mode uses 1-byte instructions even though the operand is in memory. Before using a register-indirect mode instruction, the programmer must ensure that the address of the operand is placed in the processor register with a previous transfer-type instruction. A reference to the register is then equivalent to specifying a memory address.
What is LDA in 8085?
I believe it is the Load A instruction- Load the A register. The operand would contain the value to load into the register, or if indirect, it would point to the address where the value is contained. indirect addressing can be relative or absolute.
What is defference between direct and indirect address?
Direct addressing involves specifying the exact memory address where data is stored or fetched. Indirect addressing involves using a memory address that points to where the data is stored or fetched. In direct addressing, the actual data is accessed, while in indirect addressing, a reference to the data's location is accessed.
Difference between direct addressing mode and indirect addressing modein8085 microprocessor?
When a microprocessor wants to store a byte of information in memory, or retrieve a byte of information from memory, it needs to refer to the address of the byte in the instruction. When direct addressing is used then the microprocessor instruction refers explicitly to the address that is to be used. When indirect addressing is used then the microprocessor instruction refers to a third object that refers to the address that is to be used. So, for example: Direct addressing: (*) Store the data at address 0x3C6E (*) Deliver the letter to house 12 on the street. Indirect addressing: (*) Store the data at whatever address is in register AX. (*) Deliver the letter to whichever house the occupant of house 7 tells you. So, in indirect addressing, the microprocessor instruction refers to some other "third-party" location (a register or another memory location) to find-out what the ultimate address to be used should be. The instruction does not contain all of the information needed to store the byte (or deliver the letter) but it does say where the missing information can be found. In direct addressing, the instruction contains all of the information needed to store the byte (or deliver the letter). This is basically true for all microprocessors but different microprocessors allow different forms of indirect addressing. For example, some use memory indirect addressing (the third party is another memory location), and some use register indirect addressing (the third party is a register).
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.
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
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.
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
How would you use indirect address?
An indirect address is an address contained in a register or memory location, instead of in the instruction itself. In the 8085, the most common form is to load or calculate an address in the HL register, and then access the memory pointed to by HL using the M register designation, such as MOV A,M.
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.
Difference between direct addressing mode and indirect addressing mode in detail?
Direct addressing mode means the operand address is contained in the instruction. In the 8085, an example is LDA 1234H, which loads the accumulator with the contents of memory location 1234H. In the 8086/8088, an example is MOV AL,[1234H], which accomplishes nearly the same thing.Indirect addressing mode means the operand address is contained in a register. In the 8085, an example is LDAX B, which loads the accumulator with the contents of the memory location specified in register BC. In the 8086/8088, an example is MOV AL,[BX], which accomplishes nearly the same thing.
