Enumerate data structures used during 1-pass of assembler, Computer Engineering

Assignment Help:

Enumerate the data structures used during the first pass of the assembler. Indicate the fields of these data structures and their purpose/usage.

Three main data structures used throughout the first pass of the assembler are given below:

- LOCCTR i.e. Location counter

- OPTAB i.e. operation code table

- SYMTAB i.e. Symbol table

LOCCTR: It is Location Counter that maintains track machine addresses of symbolic tables.

  • Initialized with START.
  • Raised for all instructions
  • Pseudo Instructions are: BYTE, WORD, RESB and RESW.
  • Machine Instructions are: Fixed length (i.e. 3 bytes) for SIC, variable length for SIC/XE (looking up OPTAB).
  • Allocate the value (address) of LOCCTR to consequent symbol table.

OPTAB: In this operation table mnemonic operation code and have its machine language equivalent.

346_OPTAB.png

  OPTAB can be implemented by using hashing function for fast access.

  SYMTAB: in Symbol table symbolic label, operand and their consequent machine are keeps addresses.

656_SYMTAB.png

  • SYMTAB is dynamic, constructed throughout Pass 1:

                   a. For symbolic label, fill in address and symbol (as per to current LOCCTR).

                   b. For symbolic operand, fill into symbol and mark this as undefined. Address field will be challenged later.

  • SYMTAB can be implemented by using hashing function for fast access.

Related Discussions:- Enumerate data structures used during 1-pass of assembler

Artificial intelligence software, Artificial Intelligence Software A...

Artificial Intelligence Software Artificial Intelligence (AI) software employs non numerical algorithms to resolve complex problems that are not amenable to computation or s

What is the fundamental digital design, What is the fundamental Digital Des...

What is the fundamental Digital Design? Digital design is distinct through analog design. In analog circuits we deal along with physical signals that are continuous in amplitud

Define parsing, Define Parsing Parsing is the method of analyzing a te...

Define Parsing Parsing is the method of analyzing a text, made up of a sequence of tokens, to define its grammatical structure with respect to a given formal grammar. Parsing

Explain the working principle of hard disk, Question : a) Hard disk is ...

Question : a) Hard disk is an important component of a computer. What type of memory is it? b) With the help of a diagram describe its features. c) Explain its working pr

Program size for different instruction set approaches, Q. Program size for ...

Q. Program size for different Instruction Set Approaches? Assumptions: Complex Instruction is: Add C, A, B having 16 bit addresses and 8 bit data operands All opera

Explain the working of interpreter, Explain the working of Interpreter? ...

Explain the working of Interpreter? The Interpreter is a program that executes instructions written in a high-level language. There are two manners to run programs written in a

State the approaches to organizing stored program control, Determine the ap...

Determine the approaches to organizing stored program control There are 2 approaches to organizing stored program control: 1.  Centralized: In this control, all control equi

List the steps needed to perform page replacement, List the steps needed to...

List the steps needed to perform page replacement. The steps required to perform page replacement are: 1. Find out which page is to be removed from the memory. 2. Perfor

Difference among java beans & servlets, Java bean is a reusable component, ...

Java bean is a reusable component, where as the servlet is the java program which extends the server capability.

What do you mean by polynomial and exponential bounds, What do you mean by ...

What do you mean by polynomial and exponential bounds?   Bounds of the form nc for c greater than 0 .such a bound are known as polynomial bounds. Bounds of the form 2(n )  .suc

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