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What is the name of register which contains the effective address of the operand?
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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 is meant by effective address in microprocessor?
Effective address is the final address generated by offsetting and indexing which is sent to the virtual translation logic. It is the address of the operand in the virtual address space of the process, but not necessarily the address of the operand in the physical address space of the computer. In the 8085, efffective/virtual address is the same as physical address, because there is no virtual addressing logic in the 8085. In the 8086/8088, effective/virtual address is the same as physical address, but only in real mode. For example, in the 8086/8088, if the EBX register contains 1000000H, then the instruction MOV EAX,[EBX+1234H] has an effective address of 10001234H.
What is the consists in the Instruction register?
The Instruction Register contains the current instruction being executed. It is an internal, special register, and you can not do anything explicit with it. If you are referring to the Program Counter, that simply contains the address of the next instruction to execute. It is incremented for each opcode and operand byte fetched.
What are the differences between preindexing and postindexing?
post indexing First, the contents of the address field are used to access a memory location containing a direct address. This address is then indexed by the register value. pre-indexing An address is calculated as with simple indexing. In this case, however, the calculated address contains not the operand, but the address of the operand.
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 are operands?
Every instruction contains to parts: operation code[opcode],and operand. The first part of an instruction which specifies the task to be performed by the computer is called opcode. The second part of the instruction is the data to be operated on.,and it is called operand. The operand[or data]given in the instruction may be in various forms such as 8-bit or 16-bit data, 8-bit or 16-bit address, internal register or a register or memory location.
Why accumulator is called a special register?
Accumulator contains one of the operand for any operation which is performed by the ALU.The result of the operation is stored in the Accumulator. thus it is a special register
What is the use of base pointer register?
It contains an address, which will be used in calculting the actual address of an operand. Example (Sytem/360): L R2,12(R3,R4) meaning: tempadd := 12 + R3 + R4 R2 := content of memory at tempadd here R3 is called base registed, R4 is called index register. Or vice versa.
What is a direct address in language?
It means speaking to someone directly. Susan, clean up your room. Bob, hand me a flashlight. I told you already, Mom, I am not going. In these sentences, the direct address is to Susan, Bob, and Mom.
What are the Functions of DX register?
used as implicit operand
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 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.
