Summary for the Quiz

1
Summary for the Quiz

• Device Control
• Architecture of PC
• Interrupts in PC
• Software Engineering
• Data type, variables
• Functions

2
Device Control

• Architecture of PC
• CPU, Memory, Devices, Data Bus, Address Bus
• Addresses and Enable Devices
• Interrupts in PC
• Access Register Through Turbo C
• Invoke Interrupts Through Turbo C

3
Architecture of PC

• CPU, Memory, Devices, Data Bus, Address Bus
• Connection between Them
• Addresses and Enable Devices
• Conversion among Decimal Numbers, Hexadecimal
  Numbers and Binary Numbers
• Convert Addresses to Enable Devices for Hardware
  Devices

4
Interrupts of PC

• Access Register Through Turbo C
• Use Pseudo-Variables
• Use SREGs
• Invoke Interrupts Through Turbo C
• description of interrupt in PC from handbooks
• library functions from dos.h

5
Invoke Interrupts Through Turbo C

• Description of interrupt in PC from handbooks
• chapter 11 for keyboard and 12 for video
• find out pre-condition and post-conditions of
  interrupts and their services
• Library functions from dos.h
• geninterrupt
• int86

6
Software Engineering

• Data type, variables
• int, long, double, char, ascii code
• pointer and array
• struct //user defined data type
• scope of variables (local vs global)
• Functions
• main
• library functions
• user defined functions
• parameter list

7
int, long, double

• Conversion between data types and Ascii code
• What is the output of the following examples
• int I I88888888 cout ltlt I ltltendl
• int I I8888.8888 cout ltlt I ltlt endl
• int I I9(88/9) cout ltlt I ltlt endl
• int I I9(88/9.0) cout ltlt I ltlt endl
• int I char x I97 xI cout ltlt xltlt endl

8
scope of variables (local vs global)

• local variables of the same name
• What is the output of the following program?
• void change() int x xx-1
• void main()
• int x x4 change() cout ltlt x ltlt endl

9
Pointers

• Definition of a pointer
• int x
• Address of pointer x
• Value of pointer x
• Object pointed to by pointer x
• Assign values to a pointer
• NULL
• another pointer of the same type
• address of another variable of the same type as
  the object pointed to by the pointer

10
array

• Define an array int x100
• size of array 100
• name of the array a
• element of array aI I0,1,, 99 //not 100

11
struct

• Defined data type
• struct new_data_type
• int x //member variable 1
• char y //member variable 2
• double z //member variable 3
• define a variable of this type
• new_data_type w
• access of member variables of struct
• w.x1 w.ye w.z3.14
• cout ltlt w.x ltlt w.y ltlt w.zltltendl

12
Functions

• Main()
• library functions
• user defined functions
• parameter lists

13
main ()

• Each program has exactly one main()
• Executed will start at the first line of main and
  finish at the end of main
• Inside main(), other functions can be called to
  execute.

14
Library Functions

• Include the necessary head file to call library
  functions
• iostream.h for input/output
• math.h for mathematical functions
• dos.h for interrupt invoking functions

15
User Defined Functions

• Prototype
• return type, name, parameter list
• preconditions and postconditions put down in
  comment
• Definition
• statements to be executed line by line
• Call
• invoke the function with adequate parameters

16
Parameter list

• Call by value (default)
• void unit1 (int x) x1
• int y y0 unit1(y) cout ltlt yltlt endl
• Call by reference
• void unit2 (int x) x1
• int y y0 unit2 (y) cout ltlt yltlt endl
• Another way of comparison
• printaddress1(int x) cout ltlt xltltendl
• printaddress2(int x) cout ltltxltltendl
• int y cout ltlt yltltendl
• printaddress1(y) printaddress2(y)

17
Recursive Functions

• a function call to itself inside the definition
  of a function. Such functions are called
  recursive.
• An example
• long int power(int n,int m)// the m-th power of
  n.
• if (m0) return 1 // base case
• return npower(n,m-1)

18

• Another Example calculation of n!
• long factorial(int n) //return n!
• if (n0) return 1 //base case n0
• return nfactorial(n-1) //n!n(n-1)!

19
Interrupt Function Intr()

• structure REGPACK(unsigned r_ax,r_bx,r_cx,r_dx
  unsigned r_bp,r_si,r_di,r_ds,r_es,r_flags
• void intr (int N, struct REGPACK Reg)
• the same structure is used as input/output
• r_ds_DS, r_es_ES should be set before invoke it
• otherwise it will crash

20
An Example Using Intr()
readchar() char x REGPACK R /define
variables/ R.r_ax0x0000 /_AH0x0 service
0/ R.r_es_ES / preserve ES/
R.r_ds_DS / preserve DS/
intr(0x16,R) /keyboard interrupt 0x16 /
x0x00FFR.r_ax /xAL/ return x
21
Work on the Sample Quiz now

• 1. Design a program which finds out the ASCII
  code of char f.
• 2. What is the value of bitwise of 37 and 71?
• 3. Draw the enable device for NMI (addresses
  0x70-0x7F)
• 4. Prototype a function which returns the current
  video mode.
• 5. Implement the above function by useing int86
  to invoke interrupt0x10 service 0x0F