1. COURSE OUTCOMES OF MICROPROCESSOR AND PROGRAMMING
Describe the architecture and organization of microprocessor along with instruction set format.
C404.2
Describe modes and functional block diagram of 8086 along with pins and their functions
C404.3
List and describe memory and addressing modes
C404.4
List, describe and use different types of instructions, directives and interrupts
C404.5
Develop assembly language programs using various programming tools.
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2. THE ART OF ASSEMBLY LANGUAGE PROGRAMMING
CHAPTER 4
THE ART OF ASSEMBLY LANGUAGE PROGRAMMING

3. Program development steps
Defining the problem
Algorithm
Flowchart
Initialization checklist
Choosing instruction
Converting algorithm to assembly language program

4. Defining the problem
The first steps in writing program is to think very carefully about the problem that you want to solve.
The problem is given in the form of statement or mathematical expression
Read the problem carefully and understand the problem
Expand the problem to get a clear ,concise and accurate description
E.g: read temperature from sensor

5. Algorithm
An algorithm is a step-by-step instruction require to solve any problem.
An algorithm consist of a set of explicit , finite steps which when carried out for a given set of initial condition,produce the output.

6. Flowchart
The flowchart is graphically representation of the program operation
The specific operation is represented by graphical symbol such as circle ,rectangle , diagonal, square, parallelogram.

7. Initialization checklist
In program there are many variables, constant ,and various part of the system such as segment registers ,flags ,stack , programmable port which must be initialize properly.
The best way to approach the initialization task is to make the checklist of the entire variables, constants, registers , flags &ports

8. Choosing instructions
Next steps is to choose proper instruction that performs your problem’s operation
This is an important step that breaking down the programming problems sequences of steps  easy to find the instruction solve the problem

9. Converting algorithm into assembly language
In assembly language program a first step is to set up & declare the data structure that the algorithm will be working with then write down the instruction required for initialization at the start of the code section.
Determine the instruction required to implement the major actions in the algorithm

10. Assembly language program development tools
1)Editor:
An editor is a program which helps you to construct your assembly language program in right format- translate it correctly in machine language
So you can type your program using editor
Form of the program source program.
DOS based editor such as EDIT ,wordstar &norton editor

11. Assembler
An assembly is a program that translate the program-into binary code for each instruction .i.e: machine code and generate the file called as object file with extension .obj
Example: tasm ,masm

12. Linker
A linker is a program which combines if requested more than one separately assembled module into one executable program
Example: Tlink

13. Debugger
Debugger is a program that allows the execution of program in single step mode under the control of the user.
The process of locating & correcting errors using a debugger is known as debugging
Example: DOS debug command , borland’s turbo debugger.

14. Program development process
Source file creation
Object code generation
Executable file creation
Program running
Program testing
Program debugging

15. Data definition direction
1) DB
The directive DB  to define a byte type variable
It can be used to single or multiple byte variable.
The range of values that can be stored in a byte is 0 to 255 for unsigned number & -128 to +127 for signed numbers
Name_of_variable DB initalization_value(s)

16. Dw: define word The directive Dw to define a word type
It can be used to define single or multiple word variables
The range is 0 to for unsigned numbers & to
General form:
Name of variable DW initialization value(,s)

17. DD: define double word DD used to define a double word type
Can be used to define single or multiple double word variable i.e 4 byte
Range is 0 to 2^32-1 for unsigned numbers
-2^32-1 to 2^32-1-1for signed numbers
General form:
Name_of_variable DD Initalization_value(,s)
Example: NUM DD ?=allocate four memory
locations

18. DQ: define quad word DQ is used to define a quad word type
It can be used to define single or multiple quad word variable
Range is 0 to 2^64-1 for unsigned numbers
-2^64-1 to 2^ for signed numbers
It is used in the math coprocessor instruction where large no are used in computation
General form:
Name_of _variable DQ initalization_value(,s)
Example: NUM DQ ? = allocate 8 memory location

19. DT: define ten byte DT: used to define a ten byte type variable
Can be used to define a single or multiple 10 byte variable.
Range 0 to 2^80-1 for unsigned number
-2^80-1 to 2^ for signed integer numbers
The floating point numbers range from 10^-4932 to 10^4932
The DT type variables useful in math coprocessor instruction where large numbers are used in computation

20. Name_Of _ variable DT Initalization_Value( , s)
-General form:
Name_Of _ variable DT Initalization_Value( , s)
Example:
NUM DT ? = allocate ten memory locations
TABLE DT 1,2,3,564,5689 = allocate fifty memory location -

21. LABEL
The directive LABEL enables you to redefine the attribute of a data variable or instruction label.
General form:
Variable_name LABEL type_specifier
Example:
TEMP LABEL BYTE
NUM LABEL WORD

22. ALIGN : alignment of memory address
The directive ALIGN - to force the assembler to align the next data item
General form:
ALIGN Numeric_value
-the number must be a power of 2 such as 2 ,4 ,8 ,16
Example:
ALIGN 4

23. STRUCT: structure declaration
STRUCT - to declare the data type which is primary collection of data type
Structure declaration allows the user to define a variable which has more thatn one data type.
General form:
Structure _name STRUCT
………….
; sequence of DW ,DD directives for declaring ;
; field
…………
structure_name ENDS
Example:
Employee STRUCT
emp_num DW ?
emp_name DB 25 DUP(0)
emp_dept DB 30 DUP (0)
Employee ends

24. Accessing structure variable field:
- The structure variable field can be accessed by using a dot(.) operator known as the structure access operator.
General form:
Structure_variable. Field _name
Example:
here structure variable name is emp1
emp1.emp_num
emp1. emp_name
emp1.emp_dept

25. EQU:equate to
The EQU directive  declare the symbols which some constant value is assigned.
Such symbolscalled as macro symbols
Macro assembler will replace every occurrences of the symbols
Macro increase readability of program
General form:
symbols_name EQU Expression
Example:
NUM EQU 100

26. ORG: originate
ORGassign the location counter with the value specified in the directive
Helps in placing the machine code in the specified location while translating the instruction into machine codes by the assembler.
This feature useful in buliding device drivers
General form:
ORG [$] Numeric_value
Example:
ORG 100h

27. Program organization directives
1) ASSUME :
Assume informs the assembler the name of the logical segment that should be used for a specified segment.
General form:
ASSUME
seg_reg: Seg_name,……………..seg_reg:Reg_name
Where ASSUME is a assmebler directive
Seg_reg is any of the segment register
Seg_name is the name of an user defined segment
Example:
ASSUME CS: code segment, DS: data segment

28. SEGMENT
Segment is used to indicate the beginning of the logical segment.
Segment follows the name of the segment
Segment &ends must be enclosed the segment data, code ,extra or stack of the program.
General form:
segment_name SEGMENT [WORD /PUBLIC]
WORD indicates that the segment has to be located at the next available address.
PUBLIC indicates that the given segment which have the same name.

29. Example:
code segment
………………
……………….
code ends
Data segment
Data endsaa

30. ENDS:end of the segment
ENDS  informs the assembler the end of the segment
ENDS & SEGMENTmust enclosed the segment data or code of the program.
General form:
segment_name ENDS
Example:
my_data segment
………..
My_data ENDS

31. END:end of the program
END to inform assembler the end of the program.
General form:
END[start_address]
start_address indicates the location in the code segment where execution is to begin.

32. .CODE:simplified CODE segment directive
This simplified segment directive defines the code segment.
All executable code must be placed in this segment.
General form:
.CODE [name]

33. .DATA:simplified DATA segment directive
This simplified segment directive defines the data segment for initialized near data
All data definition & decalration must be placed in this segment.
General form:
.DATA

34. .STACK : simplified STACK segment directive
It defines the stack segment & default size of the stack is bytes which you may override.
General form:
.STACK 100

35. .MODEL: memory model decalration for segment
It creates default segment.
General form:
.MODEL memory_small
Memory model:
TINY=masm 6.0 used for .com program
SMALL= all data in one segmetn & all code in one segment.
LARGE=both data &code in more than one segment

36. Value returning attribute directives
1) LENGTH:
The Lengthinforms the assemblers about the number of the elements in a data items such as array
If the array is defined in DB it return number of bytes allocated to a variable.
It the array is defined in DW it return the number of word allocated to the array variable.

37. General form:
LENGTH variable_name
Example:
MOV CX,LENGTH NAME

38. SIZE
It is same as LENGTH except that it return the number of bytes allocated to the data items instead of the number of element in it
General form:
SIZE variable_name
Example:
MOV AX, SIZE NAME

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SEG:segment
The SEG is used to determine the segment in which the specified data items is defined
General form:
SEG variable_name
Example:
MOV DS,SEG MSG
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