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

Differentiate between protection and security, Differentiate between protec...

Differentiate between protection and security. Operating system contains a collection of objects, software or hardware. All objects have a unique name and can be accessed by

How can we minimize problems occurring because of branch., Q. How can we mi...

Q. How can we minimize problems occurring because of the branch instructions? We may use various mechanisms which may minimize the effect of branch penalty. To keep mult

Define range which a normalised mantissa can signify, Now let's define rang...

Now let's define range which a normalised mantissa can signify. Let's presume that our present representations has normalised mantissa so left most bit can't be zero so it has to b

Ground substitution, Ground substitution: Here the act of performing a...

Ground substitution: Here the act of performing an instantiation is a function like there is only one possible outcome means we can write it as a function. And the notation Su

Carry save addition and generated and propagate function, Explain carry sav...

Explain carry save addition (CSA) process. Ans: Instead of allowing the carries ripple along the rows, they can be saved and then introduced into the next roe at the right wei

Write decoder functionality in only one statement in verilog, Write decoder...

Write decoder functionality in only one statement in verilog module decoder( // Outputs dout, // Inputs din ); input [3:0] din; output [15:0] dout;

Design a logic circuit, Ask questDesign a logic circuit with 4 inputs A, B,...

Ask questDesign a logic circuit with 4 inputs A, B, C & D that will produce output ‘1’ only whenever two adjacent input variables are 1’s. A & D are also to be treated as adjacent,

Illustrate the accumulator architecture, Accumulator Architecture: An accu...

Accumulator Architecture: An accumulator is anespecially designated register which supplies one instruction operand and receives result. Instructions in such machines are usually

What are latches and flipflops, What are latches and flipflops? There a...

What are latches and flipflops? There are two types of circuits as follows: a. Combinational b. Sequential Flipflops and latches both come into the category of "sequen

Authentication system differ from a firewall in functioning, How does an au...

How does an authentication system differ from a firewall in functioning?   Authentication vs. firewall User Authentication and Authorization A significant advanced fi

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