error 65: access violation at C:0xFF00 : no 'execute/read' permission

#include <REG2051.H>

#define         SL      P1_4
#define         SR      P1_5

#define         A       P1_6
#define         EN      P1_7

unsigned char F = 0x00;
unsigned char PF = 0;

void Go_To_Sleep (void)
{
PCON = 0x01;
}

void main (void)
{
        IT0 = 0;
        EX0 = 1;
        EA = 1;
        Go_To_Sleep ();
}
void Ext_Int (void) interrupt 0

{
F=~F;
if(F==0x00)
        {
        A=0;
        }
else
        {
        A=1;
        }
        while(PF==0)
        {
        EN=1;
        if(A==0)
                {
                if(SR==1)
                        {
                        PF=1;
                        }
                }
        else
                {
                if(SL==1)
                        {
                        PF=1;
                        }
                }
        }
        EN=0;
        PF=0;
}

#include <REG2051.H>

#define         SL      P1_4
#define         SR      P1_5

#define         A       P1_6
#define         EN      P1_7

unsigned char F = 0x00;
unsigned char PF = 0;

void Go_To_Sleep (void)
{
PCON = 0x01;
}

void main (void)
{
        IT0 = 0;
        EX0 = 1;
        EA = 1;
        Go_To_Sleep ();
}
void Ext_Int (void) interrupt 0

{
F=~F;
if(F==0x00)
        {
        A=0;
        }
else
        {
        A=1;
        }
        while(PF==0)
        {
        EN=1;
        if(A==0)
                {
                if(SR==1)
                        {
                        PF=1;
                        }
                }
        else
                {
                if(SL==1)
                        {
                        PF=1;
                        }
                }
        }
        EN=0;
        PF=0;
}

void Go_To_Sleep (void)
{
PCON = 0x01;
}

If you're running in the Simulator, are you sure that this actually works in the Simulator...?

You need to adopt a consistent style for indenting!

In particular, whether the braces are indented to the same column as the code they enclose, like this:

void Go_To_Sleep (void)
        {
        PCON = 0x01;
        }

(personally, I hate this)

Or whether the braces are indented to the same column as the controlling code, like this:

void Go_To_Sleep (void)
{
        PCON = 0x01;
}

(personally, I much prefer this)

I think it would also be better to reduce the size of each indenting "step"; eg, 4 characters instead of 8...

Ok,it's like this. When I run the program in the main he calls Go_To_Sleep when he shuts down the device,and stays that way. Than when I trigger the P3.2 pin he goes to interrupt code and do everything that I wanted to do,but when he finishes with interrupt and try to go back to Go_To_Sleep and do the line with PCON=0x01; disassembly windows apears with message ***error 65...

"when he finishes with interrupt and try to go back to Go_To_Sleep"

But, surely, when he "goes back" to Go_To_Sleep, he will go to the line after PCON=0x01 - won't he...?

Yes,that's right. So,is there any solution?
Sorry about my english,I'm trying.

Have you placed a bucket or something below the main() function? Exactly what do you think will happen when your processor falls out from the main() function? Who/what do you expect to catch it?

Your processor does not have a desktop or a command line that will magically appear when main() ends. At least add an infinite loop around the sleep command.

"Yes,that's right. So,is there any solution?"

Yes - think about it: the problem is that the code returns from Go_To_Sleep, but you actually want it to repeat the PCON=0x01 instruction, don't you?

Read your processor's datasheet carefully - some require a few instructions before they will go back to sleep...

Yes,I wanted to but it never happened. I salved the problem, instead of using the Go_To_Sleep function I put the PCON=0x01 into the while loop and it's working good.At least I think so.

void main (void)
{
        IT0 = 0;                                // Configure interrupt 0 for rising edge on /INT0 (P3.2)
        EX0 = 1;                                // Enable EX0 Interrupt
        EA = 1;                                 // Enable Global Interrupt Flag
        while(1)
        {
         PCON=0x01;
        }
}