Chapter 2 2 ( Leehland)

Question 1

Role of Assembler

Answer 1

Source code is converted into the object code

Question 2

Linker

Answer 2

Object code is converted into the executable code.

Question 3

Loader

Answer 3

It loads the executable code onto the memory (RAM) for it to get executed by CPU.

Question 4

Fundamental functions of the Assemblers

Answer 4

Translating the mnemonic operation codes to their machine language equivalent.

Assigning the machine addresses to the symbolic labels.

Question 5

Assemblers are machine dependent as they have different machine instructions format and _______

Answer 5

codes

Question 6

Data Transfer (RD, WD)

Answer 6

The end of each record is marked with the null character(00[subscript-16])
The end of the file is indicated by the zero-length record.

Question 7

Subroutines(JSUB, RSUB)

Answer 7

(RDREC, WRREC)
Saves the link register first before the nested jump.

Question 8

Pseudo Instructions

Answer 8

Providing instructions to the Assembler.

Not translated into the machine instructions.

Question 9

Basic Assembler Directive

Answer 9

START
END
BYTE
WORD
RESW
RESB

Question 10

Object Program

Answer 10

Header
Text
End

Question 11

End

Answer 11

E
Address of the first executable instruction (hex)
(END_PROGRAM NAME)

Question 12

TEXT

Answer 12

T
Starting address int his record (hex)
Length of the object code in this record int he bytes (hex)
Object code (69-10+1)/6 =10 instructions

Question 13

Header

Answer 13

H
Program name
Starting address (hex)
Length of the object program in bytes (hex)

Question 14

Assembler’s other functions

Answer 14

Convert the data constant into the internal machine representations
Build the machine instructions in the proper format
Write the object t program and the assembly listing.

Question 15

Forward reference

Answer 15

reference that is defined later in the program

Question 16

Two Pass Assembler:

Pass 1

Answer 16

Assign the addresses to all the statements in the program
Save the values assigned to all labels for use in Pass 2
Perform some processing of Assembler directives

Question 17

Pass 2

Answer 17

Assemble insrtuctions
Generate data values defined by the BYTE, WORD
Perform processing of Assembler directives not done in Pass 1
Write the object program and the assembly listing

Question 18

Data Structure in the assembler

Answer 18

Operation Code (OPTAB)
Symbol Table (SYMTAB)
Location Counter (LOCCTR)

Question 19

OPTAB

Answer 19

Content: menmonic, machine code (instruction format, length )etc.

Characteristic: static table

Implementation: array or hash table (easy for search)

Question 20

SYMTAB

Answer 20

Content: label name, value, flag, (type, length), etc.

Characteristic: Dynamic table (insert, delete, search)

Implementation: hash table, hashing function, non-random keys

Question 21

Machine Depedent Assembler Features

Answer 21

Instruction formats and addressing modes

Program relocation

Question 22

Machine Independent Assembler Features

Answer 22

Literals

Symbol-defining statements

Expressions

Program Blocks

Control sections and program linking

Question 23

Register Translation

Answer 23

Register Name: A, X, L, B, S, T, F, PC, SW
Their values: 0, 1, 2, 3, 4, 5, 6, 8, 9

Question 24

Address translation

Answer 24

register-memory instructions use program counter relative or base relative addressing (op m)

Format 3: 12-bit address field

base relative: 0-4095
pc-relative: -2048 - 2047

Format 4: 20-bit address field

Question 25

NOBASE

Answer 25

To inform the assembler that the contents of the base register no longer be relied upon for addressing.