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

Cookies for one page in your site, How do you turn off cookies for single p...

How do you turn off cookies for single page in your site? We can turn off the cookies for one page:- By setting the Cookie. Discard property false.

Examples of input, (i)  Input a single ASCII character into BL register wit...

(i)  Input a single ASCII character into BL register without echo on screen  CODE SEGMENT  MOV AH, 08H;         Function 08H  INT 21H          ;         the character inpu

Explain about magnetic disk, Q. Explain about Magnetic Disk? A disk is ...

Q. Explain about Magnetic Disk? A disk is circular platter constructed of nonmagnetic material known as substrate, coated with a magnetisable material. This is used for storing

Iscuss the various functions of telephone switching systems, Discuss the va...

Discuss the various functions of telephone switching systems. Telephone switching system's functions are as follows: (i) Attending: The system should be continually monito

What is literal, Meaning of Literal is:- Literal is string constant.

Meaning of Literal is:- Literal is string constant.

Role of internet in progressing sciences, Ask question #Minimum 100 wordswh...

Ask question #Minimum 100 wordswhat is the .role of internet in progressing sciences accepted#

Udp, udp connection establishment and termintion

udp connection establishment and termintion

Reading decision trees, Reading Decision Trees: However we can justifi...

Reading Decision Trees: However we can justified by see that a link between decision tree representations and logical representations that can be exploited to make it easier t

Electronic brokerage facilitate search and retrieval, How does electronic b...

How does electronic brokerage facilitate search and retrieval of information? E Brokerage facilitates search and retrieval of Information: The success aspect of a brokera

Re:- exam help, Hello there i have 4 exams of ICT and i am after a tutor wh...

Hello there i have 4 exams of ICT and i am after a tutor who can help me in those 4 subjects. One hour for each subjects will be good for me as i have sample papers ready for all s

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