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I’ve had a dead Executel 3910 in for repair for months, attacking it on and off. It’s the reason I bought my monster Agilent 16702A logic analyser and learned how to use it. I fixed the initial issue and the Executel worked, then it didn’t. This was a crash I’d not seen before. 1/7

I have THE machine that STC took around the world to demonstrate the Executel. It’s different. It has different ROMs, a different video chip and a different resistor layout to every other Executel I’ve come across. What did they know? This machine is an early one with more bodge wires... 3/7

The demo machine uses non-interlaced RGB while all the other production machines use interlaced. This makes no sense to the Viewdata people I know. Testing with Tandata Prestel terminals that also use MR9735 and non-interlaced RGB show that all the dead chips work fine in non-interlaced mode. 4/7

The board is the same between machines though.. So I could copy the ROMs, set the board up the same way and it’ll just work, right? No. Not in this case anyway. Cue a long period of troubleshooting and analyser tracing. And the occasional swear. 5/7