TEST ALL OF THE CHIPS!!!1!
In this video, Kyle and I demonstrate how the flip chip tester (FCT) works. Enjoy!
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Flip Chip Testing Progress
A quick update on our FC testing project. We are about 2/3 of the way through testing all the flip chips that are currently testable with Warren's tester. We have approximately five columns left to test in the bottom half of the backplane. Previously I reported that we had a failing 103, and two failing 216s. After I asked Vince and Michael to help me understand how to interpret the errors from the tester, and and they consulted DEC documentation, they realized that the test for the 103 had a bug. Vince updated the test vectors and tested one of his 103s, and it worked. I got the fix to the M103 test, and that solved that problem. Today, one of my students and I tested a bunch of chips in the first column of the lower half. Shortly after I left, he discovered an M617 that fails. So, there's another one to fix. But honestly, I love getting news like this, because these are all fixable things, and once they're fixed the machine should be much more functional and reliable
Setting up our new Raspberry Pi0-based Flip Chip Tester (FCT)
Today's task: get our Flip Chip Tester (FCT) up and running. For those who don't know, Flip Chips (in DEC parlance) are small circuit boards with a handle opposite an edge connector, about the size of a 3x5 card, that have a small number of discrete components on it. Each Flip Chip provides a specific set of components to a machine. The one pictured here is an M617, which provides six four-input NAND gates (two per IC). The Flip Chip would be inserted into a slot, and a wire-wrap backplane would connect it to power, ground, and upstream and downstream components. One of my favorite things to explain to students is how the PDP-12's CPU can quite literally be repaired. When FCs go bad, it's usually because some IC on the FC has failed. Of course, you can just swap out the whole FC (if you have a spare). However, they can also be easily repaired if you know what to replace and you have equivalent IC packages. Enter the Flip Chip Tester. Before he died, Warren Stearns pro