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

Determine Boolean identities using Boolean algebra, Prove the following ide...

Prove the following identities   a. A ‾B ‾C‾ + A ‾BC ‾ + AB ‾C ‾ + ABC ‾ = C ‾ b. AB + ABC + A ‾ B + AB ‾C = B + AC Ans. a. LHS = A'B'C' + A'BC' + AB'C' + ABC' =

Complicated question, Hi I need a help in this question : A telephone sw...

Hi I need a help in this question : A telephone switchboard handles ? calls on average during a rush hour, and the switchboard can at most make k connections per minute. Write a

Difference between property get, Set Value is ready to ActiveX Object from ...

Set Value is ready to ActiveX Object from the form. Let Value is retried to ActiveX Object from the form. Get- Assigns the value of an expression to a variable or property.

Strategy used for the project design, This project is divided to two parts ...

This project is divided to two parts (hardware and software) each with is subtask and consideration was given in all areas in order to meet the target specification. Solutions are

Explain demand paging, What is Demand paging? Virtual memory is commonl...

What is Demand paging? Virtual memory is commonly executed by demand paging. In demand paging, the pager brings only those essential pages into memory instead of swapping in a

What is write-through protocol, What is write-through protocol? For a w...

What is write-through protocol? For a write operation using write-through protocol during write-hit: The cache location and the major memory location are updated concurrently.

Illustrate the full form of ooa, Illustrate the Full form of OOA OOA vi...

Illustrate the Full form of OOA OOA views the world as objects consist of data structures and events that trigger operations and behaviours, for object behaviour changes. The b

For what an append query be used, For what an append query be used? It ...

For what an append query be used? It is simple to append records from one table to another using an append query. There is no requirement for the tables to have the similar num

Reduced instruction set computer architecture, The goal of computer archite...

The goal of computer architects is to design computers that are cheaper and more powerful than their predecessors. A cheaper computer has: Low hardware manufacturing cost.

What are the steps followed in testing, What are the steps followed in test...

What are the steps followed in testing? i. Unit testing - The individual components are tested in this method of testing. ii. Module testing - Related collection of independ

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