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

Flowchart for the sequence of 8251-microprocessor, Flowchart for the sequen...

Flowchart for the sequence of 8251 Whether the control, mode or sync character register is selected depends on the accessing sequence.  A flowchart of the sequencing is given i

Aaa-arithmetic instruction-microprocessor, AAA: ASCII Adjust after Additio...

AAA: ASCII Adjust after Addition operation the AAA instruction is executed after an ADD instruction that adds 2 ASCII coded operands to give a byte of outcome in the AL. The AAA i

Execution unit and bus interface unit-microprocessor, Execution Unit (EU) a...

Execution Unit (EU) and Bus Interface Unit (BIU) : 8086 consist of two processors called EU and BIU. Two Processors can work parallel. This improves speed of execution. BIU fi

Whle loop, program to accept 23 students name using while loop let your var...

program to accept 23 students name using while loop let your variable control the value negative 4

Assembly language programs-microprocessor, Assembly Language Example Progra...

Assembly Language Example Programs We studied the entire instruction set of 8086/88, pseudo-ops and assembler directives. We have explained the process of entering an assembly

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

Minecraft/Terminal issues, I am running a small minecraft server off of my ...

I am running a small minecraft server off of my old mac mini, and am having a big issue. My computer isn''t very good, and even just running this server is an issue. I use a comma

Lods-stos-string manipulating instruction-microprocessor, LODS : Load Stri...

LODS : Load String Byte or String Word:- The LODS instruction loads AL/AX register by the content of a string pointed to by DS:SI register pair. The SI is automatically modifie

Microcontroller, bello need help with a final project , I have to do a pres...

bello need help with a final project , I have to do a presentation on a digital stop watch , but I have to use edsim51 to make it wondering if you guys can help me

Hold response sequence-microprocesssor, Hold Response Sequence The HOLD...

Hold Response Sequence The HOLD pin is examined at leading edge of each clock pulse. If it is received active line by the processor before T4 of the earlier cycle/during the T1

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