ARM 7 LPC2138 interfacing Programming LCD

• I want know what is difference between "|=" and "&=" and "|" operators used on line 50 and 51 and 33.Meaning of both is assign or something else?
• Also I am a beginner in ARM C programming. So can you suggest me a good book about ARM C programming? or a free tutorial on web, will also be appreciated.
• Also the program is for 8 bit interfacing of LCD. How do I convert it to work for 4-bit configuration of LCD?
• One more, How to calculate delay for LPC2138? In program taken count is "19999" means how many seconds? Can any one show calculations?
• Last one, on line 24, why it is 0x80 + 0x40, How it will go on 2'nd line of LCD

/*
 Connections from LPC2148 to LCD Module:
 P0.0 to P0.7 used as Data bits.
 P1.16 connected to pin4 i.e. RS    - Command / Data
 P1.17 connected to pin6 i.e. E - Enable
 Pin5 of LCD Module i.e. 'R/W' connected to ground
*/ 

#include<lpc213x.h>
 

void initLCD(void);
void enable(void);
void LCD_WriteChar(char c);
void LCD_WriteString(char * string);
void LCD_Cmd(unsigned int cmd);
void delay(void);



int main(void)
{
    initLCD(); 					//LCD Now intialized and ready to Print!
    LCD_WriteString(" Welcome to ");
    LCD_Cmd(0x80 + 0x40); 		//Come to 2nd Row
    LCD_WriteString("World of ARM");
    while(1); 					// Loop forever    
    return 0; 					//This won't execute :P
}

void initLCD(void)
{
    IODIR0 = 0xFF; 				//P0.0 to P0.7 configured as Output - Using 8 Bit mode
    IODIR1 = (1<<16) | (1<<17);        //P1.16 and P1.17 configured as Output - Control Pins
    IOPIN0 = 0x0; 				//Reset Port0 to 0.   
    IOPIN1 = 0x0; 				//Reset Port1 to 0 - Which also makes RS and Enable LOW.

    							//LCD Initialization Sequence Now starts
    delay(); 					//Initial Delay
    LCD_Cmd(0x3C); 			//Function Set Command : 8 Bit Mode , 2 Rows , 5x10 Font Style
    LCD_Cmd(0x0F); 			//Display Switch Command : Display on , Cursor on , Blink on
    LCD_Cmd(0x06); 			//Input Set : Increment Mode 
    LCD_Cmd(0x01); 			//Screen Clear Command , Cursor at Home
    LCD_Cmd(0x80); 			//Not required the 1st time but needed to reposition the cursor at home after Clearing Screen 
    							//Done!
}

void enable(void)
{
    delay();
    IOPIN1 |=  (1<<17);//Enable=High
    delay();
    IOPIN1 &= ~(1<<17);//Enable=Low
    delay();
}

void LCD_WriteChar(char c)
{
    IOPIN1 |= (1<<16); //Switch to Data Mode
    IOPIN0 = (int) c; //Supply Character Code
    enable(); //Pulse Enable to process it
}

void LCD_WriteString(char * string)
{
    int c=0;
    while (string[c]!='\0')
    {
        LCD_WriteChar(string[c]);
        c++;
    }
}
        
void LCD_Cmd(unsigned int cmd)
{
    IOPIN1 = 0x0; //Enter Instruction Mode
    IOPIN0 = cmd; //Supply Instruction/Command Code
    enable(); //Pulse Enable to process it
}

void delay(void)
{
    int i=0,x=0;
    for(i=0; i<19999; i++){ x++; }
}