Simple C code for PIC18

Hello,

I have written a simple C program for PIC18F4550, using C18 compiler. The program job is to make PORTB displays the values from 0 to 254.
The problem is that, during the debugging, nothing is shown on PORTB, unless the values: 32, 64, 96, 128, 244.
This is the program:

#include <p18f4550.h>
void main(void)
{
unsigned char z;
TRISB = 0;
for (z = 0; z <255; z++)
PORTB = z;
while(1);
}

Despite the value of z is changing, PORTB has no change.
You can see the attached photo showing the problem.
So what is the problem? Is there anything missing?

PORTB has several ADC outputs... You need to specify PBADEN = OFF in your config bits..

#PRAGMA config PBADEN = OFF...

Also... When using the port as an out put... use LATB ( prevents RMW )...

Hello Ian
Thank you for your help. I tried the program with the configuration you told me about, also I tried adding some other configurations, but nothing worked, same problem.
This is the code I used:
#include <p18f4550.h>
#pragma config WDT = OFF
#pragma config MCLRE = ON
#pragma config DEBUG = ON
#pragma config LVP = OFF
#pragma config FOSC = INTOSCIO_EC
#pragma config PBADEN = OFF

void main(void)
{
unsigned char z;
TRISB = 0;
for (z = 0; z <255; z++)
{
PORTB = z;
}
while(1);
}
Also I tried to put the value in LATB then immediately clear TRISB, but it did not work.
What is the problem ?

The for-loop is so fast that you will not see anything. Add (100 ms) delay after "PORTB=z;".
EDIT: Of course you should see the port value changing in the simulator..

Something you are doing..... It works fine for me..

I think the problem is with the register display, because I wrote another simpler program (PORTB = 0x03), and I was not able to see the this value in portb, but when I simulate the program using proteus isis, it works correctly.
So I think it is a problem with the debugging in MPLAB. what do you think ?
Note that I was debugging step by step, so there is no need for a delay.

Another question.
How can I specify where the program should be in the ROM using C, C18 compiler ? like when we write ORG 0x100 in assembly.

In C you shouldn't need to... The compiler takes care of any situation...

as stated earlier: PORTB = input,. LATB=output,.

your code:
void main(void)
{
unsigned char z;
TRISB = 0;
for (z = 0; z <255; z++)
{
PORTB = z;
}
while(1);
}

Proper usage:
void main(void)
{
unsigned char z;
TRISB = 0;
for (z = 0; z <255; z++)
{
LATB = z;
}
while(1);
}

you could even do:

void main(void)
{
TRISB = 0;
for (LATB = 0;LATB <255; LATB++) {}
while(1){};
}