Please do not think that I know everything about this subject. I'm stuck for REGISTERED ones and I need some help.
@Bigdogguru
I've tested nearly 40 PAL/GAL IC with this pal reader.
- 15 of them were succesfully read.
- 25 of them is registered. So I manually investigated the boards with a multimeter, osciloscope, logic analyser.
- I could only understand 3 of them and write the equivalent equations reprogramme the device.
Actually the wendor is not a determining factor for this ICs. Because for example GAL16V8 has identical or nearly same structure for all
vendors like Atmel, Lattice, ICT.
But as I said PAL Reader only works for combinatioanal, because of the nature of the programs on them.
MAIN PROBLEM IS REGISTERED PALs/GALs
I want to give some detailed information about registered types.
If you started to a reverse engineering process of a PAL/GAL IC you have to determine if it is a registered or combinational. To do that.
* Registered programs must use CLK pin as a clock input. (clock for flip-flops in GAL/PAL). So If you see a oscillator connected to this
CLK pin you may nearly be sure that the program on it is a registered one.
* Registered programs should enable the output pins. So If the output enable pin of the PAL/GAL (For example 11. pin of PAL16R8)
is connected to ground you may nearly be sure that the program on it is a registered one.
I want to give some clues to make a system for protected registered PAL/GAL readings.
Is it possible to just remove the security fuse via a software program ?
Forget to remove security fuse via a software program. It is impossible.
At the begining I thought that it can be. So I started to find a way to remove the security fuse. There is no program or a
documentation about where the addres of the security fuse, or about the programming structure of GALs/PALs.
But I found a home type GALBlast programmer on the internet. Link is here:
Welcome to GALBlast
The source codes of the GALBlast is available and I'm very excited when I see that. If you investigate the source codes you can see
the register addresses of the PAL/GAL on a PAL. I can only find the register addresses, detailed information about gal programming
in these source codes.
So I used GALBlast win32 source codes as a based for my purpose and started to make a program just remove the security fuse.
But I nearly try everything in deep but with no success. So I can say with my own experiments removing the security fuse via a
software is impossible
Is it possible to just remove the security fuse via some hardware tricks?
For PIC16C microchip IC there is a way to do that. Increasing/ Decrasing the programming voltage, supply voltage stultifies the PIC16C ,
so you can get the codes on it.
But no one suggests this kind of tricks for PALs/GALs except a german person. His nick is wiesel. He gives some clues on the
below link.
German_Site
The site is german so if you translate it to english and look for wiesel comments you can see that he suggest a kind of
delaying the programming voltage of the PALs so the PAL ignores the security fuse while you are reading it via a GAL/PAL programmer.
However; wiesel does not give details so this information is not handy. I asked him but there is no reply.
But you can still follow the thread. He may give some information hopefully
Is it possible to just remove the security fuse via a microscope technique ?
Yes it is possible. Some firms can remove the package of the IC and jumper the security fuse using an electron microscope.
But you have to find a trusty firm. Some guys gave a firm name (
www.mefas.com) on internet. But I called them they have no service for this purposes.
My comments about PAL Reader for REGISTERED types
* You have to make an electronic system that give all of the inputs to GAL/PAL and record the inputs/outputs in memory. After that
convert these input/output datas to pld equations via a converter software that you will write
* You should understand that the programs on GALs/PALs is based on a state machine. A state machine has state transitions.
If you built up a system to catch these state transitions than you can probably understand what it does.
* This system is like a custom design fast logic analyser with a recorder on it. It should try to catch the state transitions.
* I'm an advanced programmer but to built up this system discourage me. For me making the electronics is OK.
But finding the state transitions is nearly impossible ( But charles says he has a solution) please see the link
**broken link removed**
waiting for your replies
best regards