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

Define operation code, Define Operation code. The Operation code of an ...

Define Operation code. The Operation code of an instruction is a group of  bits that explain such operations as add, sub, ,shift, mul and complement.

Dataset accept changes and data adapter update method, Explain Dataset Acce...

Explain Dataset Accept Changes and Data Adapter Update methods?  Data Adapter Update method Calls the respective INSERT, UPDATE, or DELETE statements for every inserted, update

Which datatype cannot be used to define parameters, Which datatype cannot b...

Which datatype cannot be used to define parameters. Type F datatype is not used to explain parameters.

Show the major benefits of microprocessor, Q. Show the Major benefits of mi...

Q. Show the Major benefits of microprocessor? Microprocessor is a complete CPU on a single chip. The major benefits of microprocessor are:  Powerful butCompact; can

Explain one dimensional array, Explain one dimensional arrays In one di...

Explain one dimensional arrays In one dimensional arrays array name is really a pointer to the first element in the array. Second element of the array can be accessed by using

How are standard query operators useful in linq, Standard Query Operators i...

Standard Query Operators in LINQ can be used for working with collections for any of the following and more. 1. Get total count of elements in a collection. 2. Order the resu

What is mmu, What is MMU? MMU is the Memory Management Unit. It is a sp...

What is MMU? MMU is the Memory Management Unit. It is a special memory control circuit used for executing the mapping of the virtual address space onto the physical memory.

What do you understand by electronic funds transfer, What do you understand...

What do you understand by Electronic Funds Transfer?  Electronic Funds Transfer: It's an electronic payment method that transfers the money value from one bank account to

print the sum of the numbers in the file, Make a file which kepts on every...

Make a file which kepts on every line a letter, a space, and a real number.  For example, it may look like this: e 5.4 f 3.3 c 2.2 f 1.1 c 2.2 Write a script that uses textscan to

Conversion of decimal number 25.5 into binary number, Conversion of decimal...

Conversion of decimal number 25.5 into binary number Ans. There is integer part is 25 and fractional part is 0.5.  Firstly convert the integer part 25 in its equal to binary numb

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