Hello. First off, (to the moderator) thanks for accepting me to the forum. What a great looking place to hang out!
I'm in the process of trying to understand the relationship between the physical fuse field on an MMI PAL16R6 chip to what each fuse position would be related to, in it's corresponding *.JED file. What I'm trying to do is to recreate a particular locked PA16R6 by manually recreating a JED file from what I'm seeing under my microscope of the original PAL16R6 chips die.
I've decapped the chip, and am able to examine the fuse field on the physical die, and am able to visually resolve which fuses are blown and which are not. I did a couple "test" patterns on a couple blank MMI PAL16R6 chips, then decapped them, however there doesn't appear to be a 1-1 relationship between the jed file I wrote to the chip and what I'm seeing in the fuse field on the die.
Is it possible that blowing arbitrary fuses on a PAL, then looking for them in the fuse field on the die isn't necessarily a valid direction to go in figuring out the relationship?
Wondering if anyone here has any experience in reverse engineering a PAL from the die to a jedec file that could shine some light on this for me.
Thank-you for your time.
Thomas
I'm in the process of trying to understand the relationship between the physical fuse field on an MMI PAL16R6 chip to what each fuse position would be related to, in it's corresponding *.JED file. What I'm trying to do is to recreate a particular locked PA16R6 by manually recreating a JED file from what I'm seeing under my microscope of the original PAL16R6 chips die.
I've decapped the chip, and am able to examine the fuse field on the physical die, and am able to visually resolve which fuses are blown and which are not. I did a couple "test" patterns on a couple blank MMI PAL16R6 chips, then decapped them, however there doesn't appear to be a 1-1 relationship between the jed file I wrote to the chip and what I'm seeing in the fuse field on the die.
Is it possible that blowing arbitrary fuses on a PAL, then looking for them in the fuse field on the die isn't necessarily a valid direction to go in figuring out the relationship?
Wondering if anyone here has any experience in reverse engineering a PAL from the die to a jedec file that could shine some light on this for me.
Thank-you for your time.
Thomas