Instruction formats-microprocessor, Assembly Language

Assignment Help:

Instruction Formats

A machine language instruction format has 1 or more number of fields linked with it. The first field is known as operation code field or op code field, which show the type of the operation to be performed by the CPU. The instruction format also has other fields known as operand fields. The CPU executes the instruction by using the information which reside in these fields.

There are 6 general formats of instructions in 8086 instruction set. The length of an instruction can vary from one byte to six bytes. The instruction formats are given as following:

1) One byte Instruction:  This format is just one byte long and can have theregister operands or  implied data . The least significant 3-bits of the op code are referring for specifying the register operand, if any. Or else all the 8-bits form an opcode and the operands are implied.

2) Register  to Register: This format is 2 bytes long. The first byte of the code indicatethe operation code and width of the operand indicated by w bit. The second byte of the code indicate the register operands and R/M field, as given below.

2261_instruction1.jpg

The register represented  by the REG field is 1 of the operands.  The R/M field indicate  another register or memory location, for example. the other operand.

3) Register to/from Memory with no Displacement:  This format is 2 bytes long and same as the register to register format except for the MOD field as shown.

460_instruction2.jpg

The MOD field indicates the mode of addressing. The R/M, MOD,REG and the W fields are decided inTable 3.2.

4) Register  to/from  Memory  with Displacement:  This type of instruction  format have  one or two extra bytes for displacement along with 2-byte the format of the register to/from memory without displacement. The format is given.

2109_instruction3.jpg

5) Immediate Operand to Register: In this format, the first byte and the 3-bits from the second byte which are utilized for REG field in case of register to register format are utilized for opcode. It also has one or two bytes of immediate data. The complete instruction format is as given below.

360_instruction4.jpg

6) Immediate Operand to Memory with 16-bit Displacement:  This type of instruction format requires 5 or 6 bytes for coding. The first 2 bytes have the information regardingMOD, OPCODE and R/M fields. The remaining 4 bytes have 2 bytes of displacement and 2 bytes of data as shown.

 

2472_instruction5.jpg


Related Discussions:- Instruction formats-microprocessor

Program help, Could I get an estimate on how much it would cost to write a ...

Could I get an estimate on how much it would cost to write a program in assembly language?

Memory interface-microprocessor, Memory Interface              ...

Memory Interface                                                                  Figure: Memory Modulation design The memory of a computer contain of number of memo

End-endp-assemblers directive-microprocessor, END : END of Program:- Th...

END : END of Program:- The END directive marks the ending of the assembly language program. When the assembler comes across this END directive, it avoided the source lines avai

Second generation microprocessor, IInd Generation Microprocessor : The ...

IInd Generation Microprocessor : The second generation microprocessor by using n MOS technology seemed in the market in 1973.   The Intel  8080, of nMOS  technology

Assignment, You have to write a subroutine (assembly language code using NA...

You have to write a subroutine (assembly language code using NASM) for the following equation.

Power pc-microprocessor, Power Pc : A Power PC is a microprocessor des...

Power Pc : A Power PC is a microprocessor designed to meet a standard, which was combining designed by Motorola, Apple and IBM. The PowerPC standard specifies a common instruc

Program, Write a program to separate out positive and negative numbers from...

Write a program to separate out positive and negative numbers from a given series of 16-bit hexadecimal numbers.

Convert into hex pairs, Convert 751 to hex and show what it would look like...

Convert 751 to hex and show what it would look like stored at TheNumber WORD ? (hint: answer in hex pairs)

Dq-dt-assemblers directive-microprocessor, DQ:   Define  Quad word:-  Th...

DQ:   Define  Quad word:-  This directive is taken in use to direct the assembler to reserve 4 words (8 bytes) of memory for the specified variable and can initialise it having

ADDITION-SUBTRACTION, HELLO I AM TRYING TO ADD AND SUBTRACT BUT I SEEM CAN'...

HELLO I AM TRYING TO ADD AND SUBTRACT BUT I SEEM CAN''T FIND THE CORRECT REGISTER TO PUT IN

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd