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

Performance and issues in pipelining-throughput, Performance and Issues in ...

Performance and Issues in Pipelining Throughput:  Throughput of a pipeline can be defined as the number of results that have been getting per unit time. It can be denoted as:

Find the boolean expression for the logic circuit, Find the boolean express...

Find the boolean expression for the logic circuit shown below. Ans. Output of Gate-1 (NAND) = (AB)' Output of Gate-2 (NOR) = (A'+B)' Output of Gate-3 (NOR) = [(AB)' + (

What is basic time division switching, What is Basic Time Division Switch...

What is Basic Time Division Switching? Basic Time Division Switching: The functional blocks of a memory based time division switching switch is demonstrated in figure and i

Digital forensic investigation, (a) Name five important activities invol...

(a) Name five important activities involved in a digital forensic investigation. (b) Briefly describe the three types of data that a forensic examiner has to work with. Whic

Convert logic circuit to minimised, The logic circuit shown in the given fi...

The logic circuit shown in the given figure can be minimised to Ans. The minimised figure of logic diagram is D, the output of the logic circuit is as Y=(X+Y')'+(X'+(X+

Search mechanisms in prolog - artificial intelligence, Search mechanisms in...

Search mechanisms in Prolog We can utilize this simple Prolog program to describe how Prolog searches: president(X) :- first_name(X, georgedubya), second_name(X, bush). p

Explain the microprocessor development system, Microprocessor development s...

Microprocessor development system Computer systems have undergone many changes recently. Machines that once filled large areas have been reduced to small desktop computer syste

What is collection objects in vb, Likewise to arrays but is preferred over ...

Likewise to arrays but is preferred over an array due to of the following reasons. 1. A collection objects uses less Memory than an array. 2. It gives methods to add and dele

Explain a multiprogramming operating system, Explain a multiprogramming ope...

Explain a multiprogramming operating system? A multiprogramming operating system: It is system which allows more than one active user program or part of user program to be st

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