FLASH讀寫程序（W29C020C） 
#include <REG51.H>
#include <INTRINS.H>
#include <ABSACC.H>
#include <MATH.H>
#include <stdio.h>

#define Uchar unsigned char
#define Uint  unsigned int
#define Ulong unsigned long

sbit ChipSelect=P1^4;
sbit BankPort0=P1^0;
sbit BankPort1=P1^1;
sbit WriteEn=P3^6;
sbit Led=P1^2;
bit  ErrorFlag=0;

void DelayMS ( Uchar TMS )
{
 Uchar i,j;
 for ( i=4*TMS;i>0;i-- )
  for ( j=200;j>0;j-- );
}

/*入口參數：Address為欲讀地址，0<=Address<=0x3ffff,既0-256k
  出口參數：所讀數據，0-0xff 
如：data=ReadByte(0x2ffffL);注意：一定要在地址后加L
*/
Uchar ReadByte ( Ulong Address )
{
 Uchar Banksel,ReadData;
 Uint  BankAddress;
 if ( Address>=0l&&Address<=0xffffl ){Banksel=0;BankAddress=Address;}
 if ( Address>=0x10000l&&Address<=0x1ffffl ){Banksel=1;BankAddress=Address-0x10000l;}
 if ( Address>=0x20000l&&Address<=0x2ffffl ){Banksel=2;BankAddress=Address-0x20000l;}
 if ( Address>=0x30000l&&Address<=0x3ffffl ){Banksel=3;BankAddress=Address-0x30000l;}
// else { ErrorFlag=1;goto ReadError; }
 switch(Banksel)
  {
  case 0:BankPort0=0;BankPort1=0;break;
  case 1:BankPort0=1;BankPort1=0;break;
  case 2:BankPort0=0;BankPort1=1;break;
  case 3:BankPort0=1;BankPort1=1;break;
 }
 ChipSelect=0;
 ReadData=XBYTE[BankAddress];
  _nop_();
  _nop_();
 ChipSelect=1;
 return ( ReadData );
// ReadError: ;
}

/*入口參數：Address為欲寫數據的起始地址，該地址應為128的整數倍，包括0L,注意：一定要在地址后加L
   WriteData為待寫數據，0<=WriteData<=0xff
如:for(i=0;i<=127;i++)
   WriteByte ( 0x30000L,i );
則可以把0-127寫到0x30000L-0x3007fL 
如果要寫0xbb到芯片的0x30001L,則需寫成：
   WriteByte ( 0x30000L,ReadByte(0x30000L) );
   WriteByte ( 0x30001L,0xbb );
   for ( i=0;i<126;i++ )
 WriteByte ( 0x30002L+i,ReadByte(0x30002L+i) );
這樣才可以保證其他地址內容不變
*/
void WriteByte ( Ulong Address,Uchar WriteData )
{
 Uchar Banksel;
 Uint  BankAddress;
 if      ( Address>=0&&Address<=0xffff ){Banksel=0;BankAddress=Address;}
 else if ( Address>=0x10000l&&Address<=0x1ffffl ){Banksel=1;BankAddress=Address-0x10000l;}
 else if ( Address>=0x20000l&&Address<=0x2ffffl ){Banksel=2;BankAddress=Address-0x20000l;}
 else {Banksel=3;BankAddress=Address-0x30000l;}//if ( Address>=0x30000l&&Address<=0x3ffffl )
// else { ErrorFlag=1;goto WriteError; }
 switch(Banksel)
  {
  case 0:BankPort0=0;BankPort1=0;break;
  case 1:BankPort0=1;BankPort1=0;break;
  case 2:BankPort0=0;BankPort1=1;break;
  case 3:BankPort0=1;BankPort1=1;break;
  default :break;
 }
 ChipSelect=0;
 XBYTE[BankAddress]=WriteData;
 if ( ((BankAddress+1)%128)==0 )DelayMS ( 10 );
     ChipSelect=1;
}

void DisableProtect ( void )//禁止軟件寫保護
{
 WriteByte ( 0x5555,0xaa );
 WriteByte ( 0x2aaa,0x55 );
 WriteByte ( 0x5555,0x80 );
 WriteByte ( 0x5555,0xaa );
 WriteByte ( 0x2aaa,0x55 );
 WriteByte ( 0x5555,0x20 );
 DelayMS ( 10 );
}

void EarseChip ( void )    //整片擦除為0xff，一般不調用
{
 WriteByte ( 0x5555,0xaa );
 WriteByte ( 0x2aaa,0x55 );
 WriteByte ( 0x5555,0x80 );
 WriteByte ( 0x5555,0xaa );
 WriteByte ( 0x2aaa,0x55 );
 WriteByte ( 0x5555,0x10 );
 DelayMS ( 50 );
}

void main ( void )
{
 Ulong i;
 DisableProtect ( );
 EarseChip ( );
for ( i=0x0000l;i<=0x3ffffl;i++ )
{
 WriteByte ( i,0x99 );
}
P1=ReadByte ( 0x2ffffL );
while(1);