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 the first part of the address identifies in e-mailbox, The first part ...

The first part of the address in electronic mailbox identifies? The first part of address in E-Mail identifies the user's mail box.

Why eprom chips are mounted in packages, Why EPROM chips are mounted in pac...

Why EPROM chips are mounted in packages that have transparent window? Since the erasure needs dissipating the charges trapped in the transistors of memory cells. This can be co

Explain about the mini computers, Explain about the MINI COMPUTER Minic...

Explain about the MINI COMPUTER Minicomputers are much smaller in size than mainframe computers and they are also less expensive.  The cost of these computers can differ from a

Define html, HTML is a Hyper text Markup Language and it is  Scripting La...

HTML is a Hyper text Markup Language and it is  Scripting Language

What is a flip-flop, What is a flip-flop? Ans. Flip-flop is particu...

What is a flip-flop? Ans. Flip-flop is particular bit memory cell. This stores individual bit information in its true and compliment form. It is the basic block of any sequ

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

Explain overlay structured program, Explain overlay structured program ? ...

Explain overlay structured program ? A program having overlays is termed as overlay structured program, here an overlay is a part of program that has similar load origin as som

Explain about the acoustic tablet, Explain about the Acoustic tablet Ac...

Explain about the Acoustic tablet Acoustic (or sonic) tablet use sound waves to detect a stylus position. Either strip microphones or point microphones can be used to detect th

How to upgrade to the latest version using magento connect, Upgrading Magen...

Upgrading Magento to the latest version is a fairly easy task. Copy and Paste this key magento-core/Mage_All_Latest VIA Magento Connect where it states Paste extension key to insta

Define the time required by sector to reach below read/write, is the time r...

is the time required by a sector to reach below read/write head. Latency Time is the time needed by a sector to reach below read/write head.

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