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

Why we use addressing schemes, Q Why we use addressing schemes? An ope...

Q Why we use addressing schemes? An operation code of an instruction tells the operation to be performed. This operation is executed on some data stored in memory or register.

Concept of mouse, The concept of Mouse was designed by Douglas C. Engelbart...

The concept of Mouse was designed by Douglas C. Engelbart of Stanford Research institute and first Mouse was designed by Xerox corporation.  Mouse itself is a device that gives you

Design a circuit which computes the square of a number, Design a circuit wh...

Design a circuit which computes the square of a number? This should not make use of any multiplier circuits. This should use Multiplexers and some other logic as: 1^2=0+1=1

Find out lowest propagation delay time in logic family, Which the digital l...

Which the digital logic family has the lowest propagation delay time ? Ans. ECL is the digital logic family that has the lowest propagation delay time. In ECL lowest propagati

Water chemistry, Discuss the problem when a boiler is fed with lime-soda so...

Discuss the problem when a boiler is fed with lime-soda softened water

Design issues of interconnection network, Design Issues Of Interconnection ...

Design Issues Of Interconnection Network The following are the problems, which should be considered while preparing an interconnection network. 1)   Dimension and size of n

Data parallel model - parallel programming model, In the data parallel mode...

In the data parallel model, many of the parallel work focus on performing operations on a data set. The data set is usually organized into a common structure, such as an array or a

What is ai checkers, The major programs here are Arthur Samuel's, the rote ...

The major programs here are Arthur Samuel's, the rote learning method which is a lot like a memory based method, generalization learning which is a lot like backprop and a signatur

Ict, how to become an ict enginer

how to become an ict enginer

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