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

What is demand paging, What is major difference between the Historic Unix a...

What is major difference between the Historic Unix and the new BSD release of Unix System V in terms of Memory Management? Historic Unix uses Swapping - Whole process is tran

How swapping increase overheads of the operating systems, Does swapping inc...

Does swapping increase the Operating Systems' overheads? Justify your answer. A process can be swapped out temporarily of memory to a backing store and after that brought back

Explain definition of fibonacci, Explain definition of fibonacci Where ...

Explain definition of fibonacci Where an input value gives a trivial result, it is returned directly, otherwise the function calls itself, passing a changed version of the inpu

large block , Given a RAID 3 (bit-interleaved parity) with k disks, how we...

Given a RAID 3 (bit-interleaved parity) with k disks, how well will large block transmits work? How well will it handle a high I/O request rate? Compare the performance to a one di

Explain routing tone in strowger telephony, Explain routing tone in strowge...

Explain routing tone in strowger telephony with waveforms and the timings. The call-in-progress tone or routing tone is a 400 Hz or 800 Hz intermittent pattern. In electromec

Define secondary memory, Define secondary memory. This memory holds tho...

Define secondary memory. This memory holds those pages that are not present in main memory. The secondary memory is usually a high speed disk. It is known as the swap evice, an

Explain about combinational circuits, Q. Explain about Combinational Circui...

Q. Explain about Combinational Circuits? Combinational Circuit is one of the models for parallel computers. In interconnection networks, different processors correspond with ea

Arrow keys - input commands, When the user is inputting commands into your...

When the user is inputting commands into your shell, it should identify the left, right , up and down arrow keys. To implement this, you will need to use the termios.h library to

What is tri-state logic, Three Logic Levels are used and they are High, Low...

Three Logic Levels are used and they are High, Low, High impedance state. The high and low are normal logic levels & high impedance state is electrical open circuit conditions. Tri

What do you meant by erp, Question 1: What do you meant by ERP? What ar...

Question 1: What do you meant by ERP? What are the benefits of ERP? Definition of ERP Question 2: Describe briefly the advantages of the ERP. Explanation of six advanta

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