Products > Test Equipment
Some old school instruments showing how it's done (HP 3325A and Fluke 8506a)
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SilverSolder:

--- Quote from: joeqsmith on February 23, 2021, 05:16:31 pm ---I was able to locate that same PCIe card.   As before, it passes that self test w/ the loop back connector and I was able to control the port with debug under DOS.   So pretty much back to where I started in the other thread except using the next generation programmer.   Sadly, the software is no longer offered for it but on the plus side, there is the internet.  And with the power of Google,

http://www.bitsavers.org/test_equipment/modularCircuitTechnology/jdr/

Time to hack some DOS code. 

This programmer supports U18 (74S287) which is not supported by the TL866.  No real surprise as that programmer is very limited.   On my board, the part is soldered to PCB.  Dive in and hack the Fluke or leave it.....

--- End quote ---

Don't turn it on, take it apart!  :D

Is U18 just programmed to work as a chip select?

joeqsmith:
That's what it looks like to me.  A PROM in place of a PAL for that era.   

I read through the thread you started about disassembling the proms but right from the start I was lost.  The first thing I would want to do is map out the entire hardware and that starts with this decoder.   Or I really missed something.
SilverSolder:

--- Quote from: joeqsmith on February 23, 2021, 06:01:23 pm ---That's what it looks like to me.  A PROM in place of a PAL for that era.   

I read through the thread you started about disassembling the proms but right from the start I was lost.  The first thing I would want to do is map out the entire hardware and that starts with this decoder.   Or I really missed something.

--- End quote ---

You are right, that would be a good approach.  If that PROM is desoldered, can the contents be read by your period-accurate programmer?

It would be good to get to a programming model of this thing.  We are pretty close already, just by deducing from the code...
joeqsmith:
I hacked the code and tried it out.  Back in business.  I don't think the 8080 will be this simple due to the lack of good tools.  First thing I want to know is if the GALs I tested in the cheap programmer were damaged.   

Yes, the old programmer supports this part.   I just need to remove it.  You can see why I am starting to think about a junk meter just for hacking.   

I will upload the image once I have it.    My guess is that thing is loaded with a lot of 1's and a few 0's sprinkled in the mix. 
SilverSolder:

Yeah, I've also got a "mule" meter for hacking/testing/repairing modules.  I like having at least two of each boat anchor because they can be hard to troubleshoot if you don't have a working one to compare with!

>My guess is that thing is loaded with a lot of 1's and a few 0's sprinkled in the mix.

A remarkably astute guess, you might just be right!  :D
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