In the 8086/8088 microprocessor, the code segment is used to fetch the opcode and any additional instruction bytes that might be part of the instruction, while the data segment is used to fetch and/or store any operand bytes that the instruction requires to be manipulated.This is in the case of no segment override prefix.
program counter holds the address of the next instruction.
The major difference between the 8085 and the 8086/8088 is that the 8085 is an 8 bit computer, and the 8086/8088 is a 16 bit computer.
op code is used as the value of instruction . And operand is address location where the instruction can meet.
No. The 8086 has instructions not present in the 8085. The 8086 was marketed as "source compatible" with the 8085, meaning that there was a translator program which could convert assembly language code for the 8085 into assembly language code for the 8086. However, this does not mean that the compiled 8086 assembly code would then run on an 8085; among other things, the 8086 was a true 16-bit processor, as opposed to the 8085 which was an 8-bit processor that supported a few 16-bit operations.
difference between micro operation and microinstruction
There are four segment registers in the 8086/8088, Code Segment (CS), Stack Segment (SS), Data Segment (DS), and Extra Segment (ES). As a result, there are four segments that can be directly addressed at a particular time, i.e. without an extra instruction to reload a segment register.
8086 is a pipelined processor. In 8086 to speed up the execution of a program,instruction fetching and executing the instruction are overlapped each other.This is a part of pipelined technique.
XLAT instruction converts the contents of AL register into a number stored in a memory table,this instruction perform the direct table look up technique often used to convert one code to another.An XLAT instruction 1st add the contents of this AL to BX to form a memory address within a data segment .It then copies the contents of this address into AL.This is the only instruction that adds an 8 bit number to 16-bit number.
A code is a set of words or lines made to do most of the task a command is a set of instruction given with authority.
1.procedure does occuie minimum memory space than macro.2..overhead delay in macro is absent..3.in macro machine code is generated for instructions each time when it is called but in procedure machine code for instruction is put only once in the memory..4.proc is accessed by call and set instr ..macro is accessed with the name given..
•The mov instruction carries out assignment in 8086 assembly language. •It which allows us place a number in a register or in a memory location (a variable) i.e. it assigns a value to a register or variable. Example: Store the ASCII code for the letter A in register bx.•A has ASCII code 65D (01000001B, 41H) •The following mov instruction carries out the task:•mov bx, 65d•We could also write it as:•mov bx, 41h•or mov bx, 01000001b•or mov bx, 'A'