[PIC] PIC18F2550 hex on PIC18F4550

Hey
Those MCUs are almost identical.
Can I put the hex file from 2550 on 4550? Will it work?
(I know they have different package sizes, not a problem)
Thanks in advance

2550 to 4550 should work. 4550 to 2550 should work, if registers used are ones that exist on the 2550.

How can it work?
I have some objection points on it. In first we define a controller structure "#define <p18f2550.h>" header file. It's mean where will found pin configuration. As a example pic18f4550 PORTB bit B1 is on pin no. 34. But pic18f2550 do'not have 34 pin numbers. You can see datasheet and will find that where is PORTD on pic18f2550. But it's on pic18f4550. If we write program for PORTD. Definitely it will not work.

I have put the PICKIT2 hex on PIC18F4550 and it recognizes it through USB but there is error 28.... and I don't know if it's 4550 fault or my computer is missing pickit drivers.

As the discussion above shows, it all depends on what you mean by "will it work"!
In this particular case and according to my quick glance at the data sheet, the SFRs on the PIC18F2550 and the PIC18F4550 are at the same addresses (including the config registers) and so the program will probably fit into the 'other' device and it will not crash because it is accessing the wrong SFR when it refers to a specific address but that does not equate to "working" in my opinion.
Also, the hardware will "save you" a bit in that if you refer to a port in one device that is not implemented in the other, then writing will be silently ignored and reading will return a 0. Also the software does not care which pin a port bit is connected to: it assumes that the hardware design has taken that into account. But that also does not equate to "working" for me.
If you look at the table at the bottom of Page 1 of the data sheet you will see that there are distinct physical differences in 4 of the columns between the 2 devices. This is probably why Microchip have developed and sell 2 different devices rather than just make 1 and stamp a different label on them.
However, in general, trying to use the HEX file form one device in another is asking for troubles, if not destroying the device.
My question back to the OP is why would you want to do this? If you have the source then just recompile it for the correct device. If you don't have the source then this is probably a very dangerous way to go and should not be considered.
Susan

The OP did tell what he wants to do, run the PICkit2 binary on a 4550 instead of the 2550 to which it's dedicated. He doesn't have the sources because they aren't published by Microchip.

I don't know if there's a specific incompatibility where the experiment fails. The firmware might e.g. read back the processor ID. It's surely possibly to find out what's happening, but I don't recognize the purpose.

Hey again.
I have tested that PIC18F4550 on other PC and it works OK and it is recognized as USB device and communication is OK but I didn't test everything because I didn't connect the transistors.
Now I wonder if I can safetely manufacture my PCB and solder ready circuit for PIC18F4550, or should I test with protoboard?

Btw please take a look here: http://openprog.altervista.org/OP_eng.html this project says that's its possible to run it on 4550 while it is for 2550... isn't it the same things?

Well I have 4550 at hand and that's all.