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Saturday, August 6, 2011

System Software & Compiler Construction

Q. What is a System software ?
System software is computer software designed to operate the computer hardware and to provide a platform for running application software. eg: Operating System

Q. What is an assembler ?
Assembler converts each assembly language statement into the corresponding machine-language statement.
There are two types of assemblers.
One-pass assemblers go through the source code once and assume that all symbols will be defined before any instruction that references them.

Two-pass assemblers create a table with all symbols and their values in the first pass, then use the table in a second pass to generate code.

Q.What are various steps to design an assembler?

1. Statement of problem:

2. Data structure:

3. Format of data bases:

Here we specify the format and content of each of the data bases task that must be undertaken even before describing the specific algorithm underlying the assembly design.

4 Algorithm: There are two passes in this

Q.Define Lexical Analysis
lexical analysis is the process of converting a sequence of characters into a sequence of tokens. A program or function which performs lexical analysis is called a lexical analyzer.

Q.What is YACC ?
YAAC is a computer program used as a parser generator developed by Stephen C. Johnson at AT&T for the Unix operating system. The name is an acronym for "Yet Another Compiler Compiler." It generates a parser (the part of a compiler that tries to make syntactic sense of the source code) based on an analytic grammar written in a notation similar to BNF.


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