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

Difference between non-relocatable self relocatable programs, Differentiate...

Differentiate between non-relocatable self relocatable programs. A non-relocatable program is one which cannot be executed in any memory area other than the area starting at

Show division and multiplication operation, Q. Show Division and multiplica...

Q. Show Division and multiplication operation? These operations can be represented as x + y = (N x   × 2 Ex-Ey + N y ) × 2 Ey and x-y = (N x × 2 Ex-Ey -N y ) × 2 Ey

Interrupt signal interconnection network (isin), Interrupt Signal Interconn...

Interrupt Signal Interconnection Network (ISIN) When a processor needs to send an interruption to another processor, then this interrupt initial goes to ISIN, through which it

Explain various fields in ipv6 base header, Explain various fields in IPV6 ...

Explain various fields in IPV6 base header? Although IPv6 base header is double as large as an IPv4 header, this contains less information. Given diagram demonstrates the forma

Determine about the security policy, Determine about the Security Policy ...

Determine about the Security Policy In the United States, the government has a separate organisation looking after the security measures and providing guidelines to all departm

In virtual memory system addresses used by the programmer, In a virtual mem...

In a virtual memory system, the addresses used by the programmer refers to  (A) Memory space.               (B) Physical addresses.   (C) Address space.                (D) M

What is the difference among scrollbar and scrollpane, A Scrollbar is a Co...

A Scrollbar is a Component, but not a Container while Scrollpane is a Container and handles its own events and do its own scrolling.

Can 8259 be interfaced with 8085 via the trap pin, I think yes...so if 8259...

I think yes...so if 8259 gives interrupt then it will be serviced instantly but since into pin is left hanging the insr bit will never be set...and so whenever any interrupt occurs

Prediction algorithms , The following branch prediction algorithms are sugg...

The following branch prediction algorithms are suggested: 1) Guess that the branch will be taken if the previous one was taken; predict not taken otherwise. 2) Guess that the

Explain working of bit serial associative processor, Q. Explain working of ...

Q. Explain working of Bit Serial Associative Processor? When associative processor accepts bit serial memory organization subsequently it is known as bit serial associative pr

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