Microcontroller measuring bicycle speed program - with simulation

 Please download the circuit diagram and simulation files from  http://www.51hei.com/bbs/dpj-20396-1.html
The following is the program source code:
#include "d:c51 eg51.h"
#include "d: c51 intrins.h"

sbit LCM_RS=P3^0;
sbit LCM_RW=P3^1;
sbit LCM_EN=P3^7;

#define BUSY 0x80 //constant definition
#define DATAPORT P1
#define uchar unsigned char
#define uint unsigned int
#define L 50

uchar str0[16],str1[16],count;
uint speed;
unsigned long time;

void ddelay(uint);
void lcd_wait(void);
void display();
void initLCM();
void WriteCommandLCM(uchar WCLCM,uchar BusyC);
void STR();
void account();

/*********Delay K*1ms,12.000mhz**********/

void int0_isr(void) interrupt 0 /*Remote control uses external interrupt 0, connected to P3.2 port*/
{
    unsigned int temp;
 time=count;
    TR0=0;
 temp=TH0;
 temp=((temp << 8) | TL0);
    TH0=0x3c;
    TL0=0xaf;
 count=0;
    TR0=1;
 time=time*50000+temp;
}

void time0_isr(void) interrupt 1 /* Remote control uses timer counter 1 */
{
   TH0 =0x3c;
   TL0 =0xaf;
   count++;
}

void main(void)
{
    TMOD=0x01; /*TMOD T0 selects mode 1 (16-bit timing) */
    IP|=0x01; /*INT0 interrupt priority*/
    TCON|=0x11; /*TCON EX0 falling edge trigger, start T0*/
    IE|=0x83;  
    TH0=0x3c;
    TL0=0xaf;
  
 initLCM();
    WriteCommandLCM(0x01,1); //Clear the display
 for(;;)
 {
  account();
  display();
 }
}

void account()
{
 unsigned long a; 
 if (time!=0)
 {
  a=L*360000000/time;
 }
 speed=a;
}

void STR()
{
 str0[0]='S';
 str0[1]='p';
 str0[2]='e';
    str0[3]='e';
 str0[4]='d';
 str0[5]=' '; 
 str0[6]=(speed%100000)/10000+0x30;
 str0[7]=(speed%10000)/1000+0x30;
 str0[8]=(speed%1000)/100+0x30;
 str0[9]='.';
 str0[10]=(speed%100)/10+0x30;
 str0[11]=speed%10+0x30;
 str0[12]='k';
 str0[13]='m';
 str0[14]='/';
 str0[15]='h';
}

void ddelay(uint k)
{
    uint i,j;
    for(i=0;i     {
        for(j=0;j<60;j++)
         {;}
    }
}[page]
/**********Write instructions to LCD sub-function************/

void WriteCommandLCM(uchar WCLCM,uchar BusyC)
{
    if(BusyC)lcd_wait();
 DATAPORT=WCLCM;
    LCM_RS=0; /* Select command register*/
    LCM_RW=0; // Write mode
    LCM_EN=1;
 _nop_();
 _nop_();
 _nop_();
    LCM_EN=0;

}

/**********Write data to LCD sub-function************/

void WriteDataLCM(uchar WDLCM)
{
    lcd_wait() ); // Detect busy signal
 DATAPORT=WDLCM;
    LCM_RS=1; /* Select data register   */
    LCM_RW=0; // Write mode
    LCM_EN=1;
    _nop_();
 _nop_();
 _nop_();
    LCM_EN=0;
}

/***********lcd internal waiting function*************/

void lcd_wait(void)
{ DATAPORT=0xff; //If the MCU outputs a low level
    before reading LCD , and the LCD is read as a high level, there will be a conflict, and the Proteus simulation will display the logic yellow  LCM_EN=1;     LCM_RS=0;     LCM_RW=1;     _nop_();     _nop_();  _nop_();     while(DATAPORT&BUSY)  { LCM_EN=0;     _nop_();     _nop_();     LCM_EN=1;     _nop_();     _nop_();  }     LCM_EN=0;

}

/**********LCD initialization sub-function***********/
void initLCM()
{
 DATAPORT=0;
 ddelay(15);
 WriteCommandLCM(0x38,0); //Three display mode settings, do not detect busy signal
    ddelay(5);
    WriteCommandLCM(0x38,0);
    ddelay(5);
    WriteCommandLCM(0x38,0);
    ddelay(5);

    WriteCommandLCM(0x38,1); //8-bit data transmission, 2-line display, 5*7 font, detect busy signal
    WriteCommandLCM(0x08,1); //Display off, detect busy signal
    WriteCommandLCM(0x01,1); //Clear screen, detect busy signal
    WriteCommandLCM(0x06,1); //Display cursor right shift setting, detect busy signal
    WriteCommandLCM(0x0c,1); // Display screen is turned on, cursor is not displayed, does not flash, detect busy signal
}

/****Display a character subfunction at the specified coordinate****/

void DisplayOneChar(uchar X,uchar Y,uchar DData)
{
    Y&=1;
    X&=15;
    if(Y)X|=0x40; //If y is 1 (display the second line), address code + 0X40
    X|=0x80; //The instruction code is address code + 0X80
    WriteCommandLCM(X,0);
    WriteDataLCM(DData);
}

/*******Display a string of characters at the specified coordinates subfunction*****/

void DisplayListChar(uchar X,uchar Y,uchar *DData)
{
    uchar ListLength=0;
    Y&=0x01;
    X&=0x0f;
    while(X<16)
    {
        DisplayOneChar(X,Y,DData[ListLength]);
        ListLength++;
        X++;
    }
}

void display()
{

 STR(); 
 DisplayListChar(0,0,str0);
    DisplayListChar(0,1,str1);
}