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

Are there any special rules about inlining, Are there any special rules abo...

Are there any special rules about inlining? Yes, there are some rules about inlining - a.) Any source files which used inline function should contain function's definition.

Explain r-2r ladder d/a converter, Explain R-2R ladder D/A converter. A...

Explain R-2R ladder D/A converter. Ans. R-2R ladder D/A converter: An R-2R ladder D/A converter is shown in Fig.(a). It uses resistors of only two values R and 2R. The inp

What is a spanning tree, What is a spanning Tree? A spanning tree is a ...

What is a spanning Tree? A spanning tree is a tree associated with a network. All the nodes of the graph appear on the tree once. A minimum spanning tree is a spanning tree

Explain j2ee, With respect to security, which one is the better choice? ...

With respect to security, which one is the better choice? .Net or J2EE? Explain? As per majority programmers .NET is the best one which have single vendor compare to, the

What is interrupt vector table, Interrupt vector table is always created in...

Interrupt vector table is always created in first 1K area of the memory. Explain why? When CPU receives an interrupt type number from PIC, it uses this number to look up corres

Convert number to hexadecimal and decimal, Perform the following calculatio...

Perform the following calculations assuming that all numbers are stored in 16-bit registers as 2's complement binary numbers with no overflow provision. Convert each of the numbers

Critical capabilities for superior firm performance, What are the critical ...

What are the critical capabilities for superior firm performance in e-commerce? Three firm capabilities which are critical for superior firm performance within e-commerce are:

Existential elimination, Existential Elimination : Now we have a sente...

Existential Elimination : Now we have a sentence, A, is with an  existentially quantified variable, v, so then just for every constant symbol k, that it does not appear anywhe

Explain about the voice recognition device, Explain about the Voice recogni...

Explain about the Voice recognition device Blind and partially-sighted people can communicate with a computer using microphone and software (keyboard and touch screens can't be

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