What is assembler, Computer Engineering

Assignment Help:

Q. What is Assembler?

An assembly program is used to transfer assembly language mnemonics to binary code for every instruction after the complete program has been written with support of an editor it's then assembled with help of an assembler. 

An assembler works in 2 stageswhich are: it reads your source code 2 times.  In first pass the assembler gathers all the symbols defined in the program accompanied by their offsets in symbol table.  On the 2ndpass through the source program it generates binary code for every instruction of the program and give all symbols an offset with respect to segment from symbol table.

The assembler produces three files. Object file, list file and cross reference file. The object file comprises the binary code for every instruction in program. It is created only when your program has been successfully assembled without errors.  Errors which are detected by assembler are known as the symbol errors.  For illustrationMOVE AX1, ZX1.

In the statement it reads the word MOVE and it attempts to match with mnemonic sets as there is no mnemonic with this spelling then it presumes it to be an identifier and searches for its entry in symbol table.  It doesn't even find it there hence gives an error as undeclared identifier.

List file is optional and comprises the source code, binary equivalent of every instruction and offsets of symbols in the program.  This file is for purelydocumentation purposes. A number of the assemblers available on PC are TURBO,MASM etc.


Related Discussions:- What is assembler

C++, Byteland county is very famous for luminous jewels. Luminous jewels ar...

Byteland county is very famous for luminous jewels. Luminous jewels are used in making beautiful necklaces. A necklace consists of various luminous jewels of particular colour. Nec

Shell is the exclusive feature of, Shell is the exclusive feature of? A...

Shell is the exclusive feature of? Ans. Shell is the exclusive feature of UNIX.

#title., Ask queCreate a telephone directory. The heading should be 16-poi...

Ask queCreate a telephone directory. The heading should be 16-point Arial Font in bold The rest of the document should use 10-point font size Otherheadingsshould use 10-point Cour

Define briefly about extranet, Define briefly about Extranet. Extrane...

Define briefly about Extranet. Extranet: Extranet is Extension of an Intranet which makes the latter available to outside companies or individuals along with or without

Differentiate between EPROM and EEPROM, Differentiate between EPROM and EEP...

Differentiate between EPROM and EEPROM. EPROM: The meaning of this term is Erasable PROM. This can be reprogrammed through first erasing the existing program. EPROM uses N-MO

Explain the concept of concurrent and parallel execution, The Concept of Co...

The Concept of Concurrent and Parallel Execution Real world systems are concurrent in nature and computer science is about modeling the real world. Illustrations of real world

How does computer know that overflow has happened, Q. How does computer kno...

Q. How does computer know that overflow has happened? Illustration: Add numbers 65 and 75 in 8 bit register in signed 2's complement notation.  Here expected result is

What is transformation, What is transformation? A transformation is a m...

What is transformation? A transformation is a mapping from the domain of models to the range of models. When modeling, it is significant not only to focus on customer needs, bu

Give an example of first fit and best fit algorithms, Given memory partiti...

Given memory partitions of 100k, 500k, 200k, 300k, and 600k (in order), apply first fit and best fit algorithms to place processes with the space requirement of 212k, 417k, 112k an

Write a short note on pointer declaration, Write a short note on pointer de...

Write a short note on pointer declaration A simple variable in a program is stored in a certain number of bytes at a particular memory location, or address, in the machine. Poi

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