Ademco PROM Data Format

[Al Testani]

I have an Ademco 4130 with a bad communicator PROM. Also have the
programming instructions (for using a 690 Programmer) and specific phone
number and subscriber code to put in. I can get the blank PROMs from
multiple sources. I've read the data out of the current PROMs (including the
control PROM) and, as expected, the data is seemingly incorrect. The
control PROM seems to be functioning for the major functions but I suspect
it may have some bad bits and more will appear over time.

My problem is while I can program blank parts I would do it with a
programmer other than a 690 so need the data format in the PROMS in 1's and
0's or hex format. I've tried to correlate the data I read out of the PROMs
to what the programming instuctions say but am not confident I've got it
right. I've seen that Ademco uses a reversed order for the bits and looked
at the data with and without a byte reversal and can't correlate it in any
direction.

So, is there any information anyone can provide of how the data is
physically laid out in the chips?

Also, I am under the impression that the failure mode of these old fusible
link PROMs is electromigration where previous open links grow back and 1's
become 0's. Is this correct or can the other direction of failure of a bit
also occur?

Thanks

Al Testani

 

[Al Testani]

Make that a 4160 system (not a 4130).