I learned that a bus crash is always a bus drivers fault.

This is one of the best video you have ever made.  Your determination, troubleshooting, and methods of reverse engineering were incredible.  I learned quite a bit from you.  Thank you.

As a person who replicated 5160 motherboard from IBM documentation I can say that yes, IBM schematic is full of errors. I used a known bug list, both 1983 and 1986 schematics, and STILL had to correct a bug with parity that, I have to be honest, WAS fixed in 86 schematics and one that I missed. But the replica board works in the end. :)

Your debugging reminded me of a PC issue we had way back in the early 90s that was caused by a loose screw. We replaced all the components on the motherboard, and then the motherboard itself and finally found a tiny screw that was shorting the board. Felt very stupid after two days of wasted effort.

Your meter can't stop cursing

Your determination is awesome.

My favorite Youtube channel of all times: Excellent detailled in-depth troubleshooting, showing the journey to the final problem all the way, and a contagious enthusiasm, never giving up. 🤘😁

Everyone: it's a boy! Adrian: it's a zero!

Another XT saved.  Well done.

Alternative title: "Help small microchip achieve YouTube fame"

Again, the timing diagrams are correct, you were just looking at the wrong one.  The one that specifically listed INTA was for timing between PICs in a multiple-PIC system.  You should have been looking at the RD/INTA timing diagram, which specified the timing for a single-PIC system.  It's just that the timing for receipt of RD is identical to the timing for receipt of the INTA signal.

Adrian this reminds me of something that happened 30 or 40 or so years ago.  I was working for a HiFi store and needed a fuse.  So I went to our repair center that was closed at the time (late at night) and was looking for this odd fuse.  I found a tray that said "Ball Busters."   I opened the tray and their was every part that over the many years gave one of our technicians grief.  I must have laughed till I cried.  I gave him a hug the next day!

Ah the good old days, individual logic IC's, where you could do anything with it, unlike later machines where it's all hidden in some large chip.

My favourite kind of video, and what a niggly little failure mode which only affected interrupt servicing. I was playing along too, stopping the video so I could go check the schematics to see if I could figure out where you should look next, fun fun!

Selection logic will get you every time

A trick to temporarily work around a loose IC socket is to put a round pin socket into the loose one and then plug the IC into that, as the round pins are larger they make better contact into the loose socket, obviously once problem is confirmed it is best to just replace the loose socket.

"Round hole socket" = turned pin, "non-round hole" = leaf spring.

I knew, I knew, right from the beginning, that you would figure it out. In the first video you were trying high level quick diagnostic stuff, and in the second video you slowed down and started using logic and figured it out.

25:05 it might be hard to follow, but you are always easy to listen to.

Please put out more content like this! This is my favorite kind of video you do.