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

Draw a circuit of TTL gates with Wired-AND connection, Draw a circuit of TT...

Draw a circuit of TTL gates with Wired-AND connection and explain its operation. Wired - AND Connection In digital IC's NAND and NOR gates are most frequently used. For th

Example of frames format with ethernet, Compute the number of Ethernet fram...

Compute the number of Ethernet frames formed for a data of 64 KB IP packet. Following figure demonstrates the format of the Ethernet frame. Here maximum data into a frame is 15

Storing a word in memory - computer architecture, Storing a word in Memory:...

Storing a word in Memory: That is similar process with fetching a word from memory. The required address is loaded into the MAR After that data to be written are lo

What are different control function categories, What are different control ...

What are different control function categories. Explain. In several switching systems, the control subsystem may be an integral part of the switching network itself. This syst

Where do you set automatic correlation options, Automatic correlation from ...

Automatic correlation from web point of sight can be set in recording options and correlation tab. Here we can enable correlation for the whole script and choose either issue onlin

Explain handlers classification, Handlers Classification In 1977, Wolfg...

Handlers Classification In 1977, Wolfgang Handler suggested a complex notation for representing the pipelining and parallelism of computers. Handler's categorization addresses

What is decision support system and describe its components, Q. What is a D...

Q. What is a DSS and Describe its components? A decision support system (DSS) is a highly flexible and interactive IT system that is designed to support decision making when t

Asynchronous and Synchronous types of serial communication, Differentiate b...

Differentiate between asynchronous and synchronous types of serial communication. Serial data communication uses two fundamental types, asynchronous andsynchronous. With synchr

Define usb, Define USB. The Universal Serial Bus(USB) is an industry st...

Define USB. The Universal Serial Bus(USB) is an industry standard developed to give two speed of operation known as low-speed and full-speed. They provide simple, low cost and

Goals and design principles, This is an applied unit that shows you how to ...

This is an applied unit that shows you how to assess interactive products against a selection of usability and user experience goals. It also introduces a selection of design princ

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