next topic »

[on:]

Hi all, I have an ancient device that I am mapping out a schematic for. The bulk of the device is shift registers, but  there are also 4 Programmable Array Logic devices. (PAL16L8ACN)
Does anyone here have any experience generating fuse-maps from existing PAL ICs? I do not have the original Fuse map, and as of yet, i have no idea how to determine the setup of these devices.
Anyone have some tips?

[Reply #1 on:]

It's likely the chip is programed like a PROM.  You should find the datasheet (http://datasheet.elcodis.com/pdf2/75/52/755267/pal16l8bcn.pdf)  and see if i has a read/verify process.  Shouldn't be hard to program the Arduino to read back the programming.

The 16L8 has 10 inputs and 8 outputs.  All models have a 32x64 programmable AND array.

"Security Fuse
After programming and verification, a PAL16R8 Family design can be secured by programming the security fuse. Once programmed, this fuse defeats readback of the internal programmed pattern by a device program- mer, securing proprietary designs from competitors. When the security fuse is programmed, the array will read as if every fuse is programmed."

That means you may not be able to directly read the contents.  You could step through all possible patterns of inputs to get the truth table and reverse-engineer the fuses from there.